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features provides analog transmission line interface for t1 and e1 applications drop-in replacement for cs61574 with the following enhancements: - lower power consumption - transmitter short-circuit current limiting - greater transmitter immunity to line reflections - software selection between 75 w and 120 w e1 output options - internally controlled e1 pulse width - b8zs/hdb3/ami encoder/decoder general description the cs61577 is a drop-in replacement for the cs61574, and combines the complete analog transmit and receive line interface for t1 or e1 applications in a low power, 28-pin device operating from a +5v supply. the cs61577 supports processor-based or stand- alone operation and interfaces with industry standard t1 and e1 framers. the receiver uses a digital delay-locked-loop which is continuously calibrated from a crystal reference to pro- vide excellent stability and jitter tolerance. the receiver includes a jitter attenuator optimized for minimum delay in switching and transmission applications. the trans- mitter provides internal pulse shaping to insure compliance with t1 and e1 pulse template specifica- tions. applications interfacing network equipment such as dacs and channel banks to a dsx-1 cross connect building channel service units ordering information CS61577-IP1 28 pin plastic dip cs61577-il1 28 pin plastic plcc may 96 ds155pp2 1 crystal semiconductor corporation p. o. box 17847, austin, texas, 78760 (512) 445-7222 fax:(512) 445-7581 t1/e1 line interface ttip tclk 7 rring rtip tring tgnd 14 control line receiver line driver 15 3 2 6 4 rclk 8 27 lloop (sclk) 25 24 (int) len0 (sdi) len1 (sdo) len2 28 23 (clke) taos 5 mode tpos [tdata] rpos [rdata] rneg [bpv] tneg [tcode] mtip [rcode] dpm [ais] los 12 21 rv+ 22 rgnd 13 19 20 17 11 18 16 mring [pcs] xtalin 9 xtalout 10 aclki 1 ( ) = pin function in host mode [ ] = pin function in extended hardware mode 26 rloop (cs) r e m o t e l o o p b a c k ami, b8zs, hdb3, coder jitter attenuator pulse shaper clock & data recovery signal quality monitor driver monitor tv+ l o c a l l o o p b a c k copyright ? crystal semiconductor corporation 1996 (all rights reserved) cs61577 this document contains information for a new product. crystal semiconductor reserves the right to modify this product without notice. preliminary product information
absolute maximum ratings parameter symbol min max units dc supply (referenced to rgnd=tgnd=0v) rv+ tv+ - - 6.0 (rv+) + 0.3 v v input voltage, any pin (note 1) v in rgnd-0.3 (rv+) + 0.3 v input current, any pin (note 2) i in -10 10 ma ambient operating temperature t a -40 85 c storage temperature t stg -65 150 c warning:operations at or beyond these limits may result in permanent damage to the device. normal operation is not guaranteed at these extremes. notes: 1. excluding rtip, rring, which must stay within -6v to (rv+) + 0.3v. 2. transient currents of up to 100 ma will not cause scr latch-up. also ttip, tring, tv+ and tgnd can withstand a continuous current of 100 ma. recommended operating conditions parameter symbol min typ max units dc supply (note 3) rv+, tv+ 4.75 5.0 5.25 v ambient operating temperature t a -40 25 85 c power consumption (notes 4,5) p c -400500mw power consumption (notes 4,6) p c -230-mw notes: 3. tv+ must not exceed rv+ by more than 0.3v. 4. power consumption while driving line load over operating temperature range. includes ic and load. digital input levels are within 10% of the supply rails and digital outputs are driving a 50 pf capacitive load. 5. assumes 100% ones density and maximum line length at 5.25v. 6. assumes 50% ones density and 300ft. line length at 5.0v. digital characteristics (ta = -40 c to 85 c; tv+, rv+ = 5.0v 5%; gnd = 0v) parameter symbol min typ max units high-level input voltage (notes 7, 8) pins 1-4, 17, 18, 23-28 v ih 2.0 - - v low-level input voltage (notes 7, 8) pins 1-4, 17, 18, 23-28 v il --0.8v high-level output voltage (notes 7, 8, 9) i out = -40 m a pins 6-8, 11, 12, 25 v oh 4.0 - - v low-level output voltage (notes 7, 8, 9) i out = 1.6 ma pins 6-8, 11, 12, 23, 25 v ol --0.4v input leakage current (except pin 5) - - 10 m a low-level input voltage, pin 5 v il --0.2v high-level input voltage, pin 5 v ih (rv+) - 0.2 - - v mid-level input voltage, pin 5 (note 10) v im 2.3 - 2.7 v notes: 7. in extended hardware mode, pins 17 and 18 are digital inputs. in host mode, pin 23 is an open drain output and pin 25 is a tristate output. 8. this specification guarantees ttl compatibility (v oh = 2.4v @ i out = -40 m a). 9. output drivers will drive cmos logic levels into a cmos load. 10. as an alternative to supplying a 2.3-to-2.7v input, this pin may be left floating. cs61577 2 ds155pp2
analog specifications (ta = -40 c to 85 c; tv+, rv+ = 5.0v 5%; gnd = 0v) parameter min typ max units transmitter ami output pulse amplitudes (note 11) e1, 75 w (note 12) e1, 120 w (note 13) t1, (fcc part 68) (note 14) t1, dsx-1 (note 15) 2.14 2.7 2.7 2.4 2.37 3.0 3.0 3.0 2.6 3.3 3.3 3.6 v v v v load presented to transmitter output (note 11) - 25 - w jitter added during remote loopback (note 16) 10hz - 8khz 8khz - 40khz 10hz - 40khz broad band - - - - 0.005 0.008 0.010 0.015 - - - - ui ui ui ui power in 2khz band about 772khz (notes 11, 17) 12.6 15 17.9 dbm power in 2khz band about 1.544mhz (notes 11, 17) (referenced to power in 2khz band at 772khz) -29 -38 - db positive to negative pulse imbalance (notes 11, 17) - 0.2 0.5 db transmitter output impedance (notes 17, 18) - - 10 w transmitter short circuit current (notes 11, 19) - - 50 ma rms notes: 11. using a 0.47 m f capacitor in series with the primary of a transformer recommended in the applications section. 12. pulse amplitude measured at the output of the transformer across a 75 w load for line length settings len2/1/0 = 0/0/1 and 0/0/0. for len2/1/0 = 0/0/0 only, a 4.4 w resistor is required in series with the transformer primary. 13. pulse amplitude measured at the output of the transformer across a 120 w load for line length setting len2/1/0 = 0/0/0. 14. pulse amplitude measured at the output of the transformer across a 100 w load for line length setting len2/1/0 = 0/1/0. 15. pulse amplitude measured at the dsx-1 cross-connect for all line length settings from len2/1/0 = 0/1/1 to len2/1/0 = 1/1/1. 16. input signal to rtip/rring is jitter free. values will reduce slightly if jitter free clock is input to tclk. 17. not production tested. parameters guaranteed by design and characterization. 18. measured between the ttip and tring pins at 772 khz during marks and spaces. 19. measured broadband through a 0.5 w resistor across the secondary of the transmitter transformer during the transmission of an all ones data pattern with len2/1/0 = 0/0/0 or 0/0/1. cs61577 ds155pp2 3
analog specifications (ta = -40 c to 85 c; tv+, rv+ = 5.0v 5%; gnd = 0v) parameter min typ max units receiver rtip/rring input impedance - 50k - w sensitivity below dsx (0db = 2.4v) -13.6 500 - - - - db mv loss of signal threshold - 0.30 - v data decision threshold t1, dsx-1 (note 20) t1, dsx-1 (note 21) t1, (fcc part 68) and e1 (note 22) 60 53 45 65 65 50 70 77 55 % of peak % of peak % of peak allowable consecutive zeros before los 160 175 190 bits receiver input jitter tolerance (note 23) 10khz - 100khz 2khz 10hz and below 0.4 6.0 300 - - - - - - ui ui ui jitter attenuator jitter attenuation curve corner frequency (notes 17, 24) - 6 - hz attenuation at 10khz jitter frequency (notes 17, 24) - 50 - db attenuator input jitter tolerance (before onset of fifo overflow or underflow protection) (notes 17, 24) 12 23 - ui notes: 20. for input amplitude of 1.2 v pk to 4.14 v pk . 21. for input amplitude of 0.5 v pk to 1.2 v pk and from 4.14 v pk to rv+. 22. for input amplitude of 1.05 v pk to 3.3 v pk . 23. jitter tolerance increases at lower frequencies. see figure 11. 24. attenuation measured with input jitter equal to 3/4 of measured jitter tolerance. circuit attenuates jitter at 20 db/decade above the corner frequency. see figure 12. output jitter can increase significantly when more than 12 uis are input to the attenuator. see discussion in the text section. cs61577 4 ds155pp2
e1 switching characteristics (ta = -40 c to 85 c; tv+, rv+ = 5.0v 5%; gnd = 0v; inputs: logic 0 = 0v, logic 1 = rv+; see figures 1, 2, & 3) parameter symbol min typ max units crystal frequency (note 25) f c - 8.192000 - mhz tclk frequency f tclk -2.048-mhz tclk duty cycle for len2/1/0 = 0/0/0 (note 32) t pwh2 /t pw2 40 50 60 % aclki frequency (note 26) f aclki -2.048-mhz rclk duty cycle (note 27) t pwh1 /t pw1 45 50 55 % rise time, all digital outputs (note 28) t r - - 85 ns fall time, all digital outputs (note 28) t f - - 85 ns tpos/tneg (tdata) to tclk falling setup time t su2 25 - - ns tclk falling to tpos/tneg (tdata) hold time t h2 25 - - ns rpos/rneg valid before rclk falling (note 29) t su1 100 194 - ns rdata valid before rclk falling (note 30) t su1 100 194 - ns rpos/rneg valid before rclk rising (note 31) t su1 100 194 - ns rpos/rneg valid after rclk falling (note 29) t h1 100 194 - ns rdata valid after rclk falling (note 30) t h1 100 194 - ns rpos/rneg valid after rclk rising (note 31) t h1 100 194 - ns t1 switching characteristics (ta = -40 c to 85 c; tv+, rv+ = 5.0v 5%; gnd = 0v; inputs: logic 0 = 0v, logic 1 = rv+; see figures 1, 2, & 3) parameter symbol min typ max units crystal frequency (note 25) f c - 6.176000 - mhz tclk frequency f tclk -1.544-mhz aclki frequency (note 26) f aclki -1.544-mhz rclk duty cycle (note 27) t pwh1 /t pw1 45 50 55 % rise time, all digital outputs (note 28) t r - - 85 ns fall time, all digital outputs (note 28) t f - - 85 ns tpos/tneg (tdata) to tclk falling setup time t su2 25 - - ns tclk falling to tpos/tneg (tdata) hold time t h2 25 - - ns rpos/rneg valid before rclk falling (note 29) t su1 150 274 - ns rdata valid before rclk falling (note 30) t su1 150 274 - ns rpos/rneg valid before rclk rising (note 31) t su1 150 274 - ns rpos/rneg valid after rclk falling (note 29) t h1 150 274 - ns rdata valid after rclk falling (note 30) t h1 150 274 - ns rpos/rneg valid after rclk rising (note 31) t h1 150 274 - ns notes: 25. crystal must meet specifications described in cxt6176/cxt8192 data sheet. 26. aclki provided by an external source or tclk. 27. rclk duty cycle will be 62.5% or 37.5% when jitter attenuator limits are reached. 28. at max load of 1.6 ma and 50 pf. 29. host mode (clke = 1). 30. extended hardware mode. 31. hardware mode, or host mode (clke = 0) 32. the transmitted pulse width does not depend on the tclk duty cycle. cs61577 ds155pp2 5
switching characteristics (ta = -40 to 85 c; tv+, rv+ = 5%; inputs: logic 0 = 0v, logic 1 = rv+) parameter symbol min typ max units sdi to sclk setup time t dc 50 - - ns sclk to sdi hold time t cdh 50 - - ns sclk low time t cl 240 - - ns sclk high time t ch 240 - - ns sclk rise and fall time t r , t f - - 50 ns cs to sclk setup time t cc 50 - - ns sclk to cs hold time t cch 50 - - ns cs inactive time t cwh 250 - - ns sclk to sdo valid (note 33) t cdv - - 200 ns cs to sdo high z t cdz - 100 - ns input valid to pcs falling setup time t su4 50 - - ns pcs rising to input invalid hold time t h4 50 - - ns pcs active low time t pcsl 250 - - ns notes: 33. output load capacitance = 50pf any digital output t r t f 10% 10% 90% 90% figure 1. signal rise and fall characteristics rclk t pw1 t pwl1 t pwh1 host mode (clke = 1) extended hardware mode or hardware host mode (clke = 0) mode or rclk rpos rneg su1 h1 tt rdata bpv figure 2. recovered clock and data switching characteristics cs61577 6 ds155pp2
tclk tpos/tneg t su2 t h2 t pwh2 t pw2 figure 3. transmit clock and data switching characteristics t dc t cc lsb lsb msb control byte data byte cs sclk sdi t ch t cwh t cch t cdh t cl t cdh figure 4. serial port write timing diagram high z cs sclk sdo clke = 1 t cdz cdv t figure 5. serial port read timing diagram pcs valid input data len0/1/2, taos, rloop, lloop, rcode, tcode rloop, lloop, t h4 t su4 t pcsl figure 6. extended hardware mode parallel chip select timing diagram cs61577 ds155pp2 7
theory of operation cs61577 enhancements relative to cs61574 existing designs using the cs61574 can be con- verted to the higher performance, pin-compatible cs61577 with no changes to the pcb, external component or system software. the cs61577 provides higher performance and more features than the cs61574 including: selection of 75 w or 12 0 w e1 output op- tions under software or hardware control, 50 ma rms transmitter short-circuit current limiting for e1 (per oftel otr-001), internally controlled pulse width for e1 output options, 35% lower power consumption, increased transmitter immunity to signal re- flections for improved signal quality, optional ami, b8zs, hdb3 encoder/de- coder or external line coding support, receiver ais (unframed all ones) detection, improved receiver loss of signal handling (los set at power-up, reset upon receipt of 3 ones in 32 bit periods with no more than 15 consecutive zeros), transmitter ttip and tring outputs are forced low when tclk is static, the driver performance monitor operates over a wider range of input signal levels. introduction to operating modes the cs61577 supports three operating modes which are selected by the level of the mode pin as shown in tables 1 and 2, figure 7, and figures a1-a3 of the applications section. the modes are hardware mode, extended hard- ware mode, and host mode. in hardware and extended hardware modes, discrete pins are used to configure and monitor the device. the ex- tended hardware mode provides a parallel chip select input which latches the control inputs al- lowing individual ics to be configured using a common set of control lines. in the host mode, an external processor monitors and configures the device through a serial interface. there are thir- teen multi-function pins whose functionality is determined by the operating mode. (see table 2). hardware mode extended hardware mode host mode control method control pins control pins with parallel chip select serial interface mode pin level <0.2 v floating or 2.5 v >(rv+)-0.2 v line coding external internal- ami, b8zs, or hdb3 external ais detection no yes no driver performance monitor ye s n o ye s table 1. differences between operating modes mode function pin hardware extended hardware host transmitter 3tpos tdata tpos 4tneg tcode tneg receiver/dpm 6 rneg bpv rneg 7rpos rdata rpos 11 dpm ais dpm 17 mtip rcode mtip 18 mring - mring control 18 - pcs - 23 len0 len0 int 24 len1 len1 sdi 25 len2 len2 sdo 26 rloop rloop cs 27 lloop lloop sclk 2 8 ta o s ta o s c l k e table 2. pin definitions cs61577 8 ds155pp2
tpos tneg rneg rpos transmit transformer rring receive transformer control cs62180b framer circuit ttip tdata rdata tring line driver ami b8zs, hdb3, coder transmit transformer rloop pcs len0/1/2 lloop taos control hardware mode extended hardware mode host mode control 5 m p serial port rcode tcode clke bpv ais jitter attenuator driver monitor line driver line receiver mtip mring dpm rtip ttip tring t1 or e1 repeater or mux cs61577 cs61577 ttip tpos tneg rneg tring rpos rring rtip rloop len0/1/2 lloop taos control dpm driver monitor line driver line receiver mtip mring cs61577 cs62180b framer circuit jitter attenuator transmit transformer receive transformer receive transformer rring rtip ais detect jitter attenuator line receiver figure 7. overview of operating modes cs61577 ds155pp2 9
transmitter the transmitter takes digital t1 or e1 input data and drives appropriately shaped bipolar pulses onto a transmission line through a 1:2 trans- former. the transmit data (tpos & tneg or tdata) is supplied synchronously and sampled on the falling edge of the input clock, tclk. either t1 (dsx-1 or network interface) or e1 ccitt g.703 pulse shapes may be selected. pulse shaping and signal level are controlled by "line length select" inputs as shown in table 3. for t1 dsx-1 applications, line lengths from 0 to 655 feet (as measured from the transmitter to the dsx-1 cross connect) may be selected. the five partition arrangement in table 3 meets ansi t1.102 and at&t cb-119 requirements when using #22 abam cable. a typical output pulse is shown in figure 8. these pulse settings can also be used to meet ccitt pulse shape requirements for 1.544 mhz operation. for t1 network interface applications, two addi- tional options are provided. note that the optimal pulse width for part 68 (324 ns) is narrower than the optimal pulse width for dsx-1 (350 ns). the cs61577 automatically adjusts the pulse width based upon the "line length" selection made. the e1 g.703 pulse shape is supported with line length selections len2/1/0=0/0/0 or len2/1/0=0/0/1. as with the cs61574, len2/1/0=0/0/0 supports the 120 w , 3 v output option without external series resistors, but will also support the 75 w , 2.37 v output option with an external 4.4 w resistor in series with ttip or tring. the new len2/1/0=0/0/1 code supports the 75 w , 2.37 v output option without external series resistors allowing for software selection be- tween the two e1 output options. the pulse width will meet the g.703 pulse shape template shown in figure 9, and specified in table 4. the cs61577 will detect a static tclk, and will force ttip and tring low to prevent transmis- sion when data is not present. when any transmit control pin (taos, len0-2 or lloop) is tog- gled, the transmitter outputs will require approximately 22 bit periods to stabilize. the transmitter will take longer to stabilize when rloop is selected because the timing circuitry must adjust to the new frequency. 500 1.0 0.5 0 -0.5 0 250 750 1000 normalized amplitude at&t cb 119 specifications pulse shape output time (nanoseconds) ansi t1.102, figure 8. typical pulse shape at dsx-1 cross connect len2 len1 len0 option selected application 0 1 1 0-133 feet dsx-1 abam (at&t 600b or 600c) 100 133-266 feet 101 266-399 feet 110 399-533 feet 111 533-655 feet 000 75 w (with 4.4 w resistor) & 120 w e1 ccitt g.703 001 75 w (without 4.4 w resistor) 0 1 0 fcc part 68, opt. a network interface 011 ansi t1.403 table 3. line length selection cs61577 10 ds155pp2
transmit all ones select the transmitter provides for all ones insertion at the frequency of tclk. transmit all ones is se- lected when taos goes high, and causes continuous ones to be transmitted on the line (ttip and tring). in this mode, the tpos and tneg (or tdata) inputs are ignored. if remote loopback is in effect, any taos request will be ignored. receiver the receiver extracts data and clock from an ami (alternate mark inversion) coded signal and out- puts clock and synchronized data. the receiver is sensitive to signals over the entire range of abam cable lengths and requires no equalization or albo (automatic line build out) circuits. the signal is received on both ends of a center- tapped, center-grounded transformer. the transformer is center tapped on the ic side. the clock and data recovery circuit exceeds the jitter tolerance specifications of publications 43802, 43801, at&t 62411, tr-tsy-000170, and ccitt rec. g.823. a block diagram of the receiver is shown in fig- ure 10. the two leads of the transformer (rtip and rring) have opposite polarity allowing the receiver to treat rtip and rring as unipolar sig- nals. comparators are used to detect pulses on rtip and rring. the comparator thresholds are dynamically established at a percent of the peak level (50% of peak for e1, 65% of peak for t1; with the slicing level selected by len2/1/0 in- puts). the leading edge of an incoming data pulse trig- gers the clock phase selector. the phase selector chooses one of the 13 available phases which the delay line produces for each bit period. the out- 269 ns 244 ns 194 ns 219 ns 488 ns nominal pulse 0 10 50 80 90 100 110 120 -10 -20 percent of nominal peak voltage figure 9. mask of the pulse at the 2048 kbps interface for coaxial cable, 75 w load and transformer specified in application section. for shielded twisted pair, 120 w load and transformer specified in application section. nominal peak voltage of a mark (pulse) 2.37 v 3 v peak voltage of a space (no pulse) 0 0.237 v 0 0.30 v nominal pulse width 244 ns ratio of the amplitudes of positive and negative pulses at the center of the pulse interval 0.95 to 1.05* ratio of the widths of positive and negative pulses at the nominal half amplitude 0.95 to 1.05* * when configured with a 0.47 m f nonpolarized capacitor in series with the tx transformer primary as shown in figures a1, a2 and a3. table 4. ccitt g.703 specifications cs61577 ds155pp2 11
put from the phase selector feeds the clock and data recovery circuits which generate the recov- ered clock and sample the incoming signal at appropriate intervals to recover the data. data sampling will continue at the periods se- lected by the phase selector until an incoming pulse deviates enough to cause a new phase to be selected for data sampling. the phases of the de- lay line are selected and updated to allow as much as 0.4 ui of jitter from 10 khz to 100 khz, with- out error. the jitter tolerance of the receiver exceeds that shown in figure 11. additionally, this method of clock and data recovery is tolerant of long strings of consecutive zeros. the data sampler will continuously sample data based on its last input until a new pulse arrives to update the clock phase selector. the delay line is continuously calibrated using the crystal oscillator reference clock. the delay line produces 13 phases for each cycle of the ref- erence clock. in effect, the 13 phases are analogous to a 20 mhz clock when the reference clock is 1.544 mhz. this implementation utilizes the benefits of a 20 mhz clock for clock recovery without actually having the clock present to im- pede analog circuit performance. in the hardware mode, data at rpos and rneg should be sampled on the rising edge of rclk, the recovered clock. in the extended hardware mode, data at rdata should be sampled on the falling edge of rclk. in the host mode, clke determines the clock polarity for which output data should be sampled as shown in table 5. 10 1k 10k 1 100 100k 700 .1 1 10 100 .4 28 300 300 peak-to-peak jitter (unit intervals) jitter frequency (hz) at&t 62411 138 minimum performance figure 11. minimum input jitter tolerance of receiver (clock recovery circuit and jitter attenuator) 1 : 2 rtip rring rpos rneg rclk data level slicer data sampling & clock extraction jitter attenuator edge detector clock phase selector continuously calibrated delay line figure 10. receiver block diagram cs61577 12 ds155pp2
loss of signal the receiver will indicate loss of signal after power-up, reset or upon receiving 175 consecu- tive zeros. a digital counter counts received zeros, based on rclk cycles. a zero is received when the rtip and rring inputs are below the input comparator slicing threshold level estab- lished by the peak detector. after the signal is removed for a period of time the data slicing threshold level decays to approximately 300 mv peak . the receiver reports loss of signal by setting the loss of signal pin, los, high. if the serial inter- face is used, the los bit will be set and an interrupt will be issued on int (unless disabled). los will return low (asserting the int pin again in host mode) upon receipt of 3 ones in 32 bit periods with no more than 15 consecutive zeros. note that in the host mode, los is simultane- ously available from both the register and pin 12. rpos/rneg or rdata are forced low during los unless the jitter attenuator is disabled. (see "jitter attenuator" section) if aclki is present during the los state, aclki is switched into the input of the jitter attenuator, resulting in rclk matching the frequency of aclki. the jitter attenuator buffers any instanta- neous changes in phase between the last recovered clock and the aclki reference clock. this means that rclk will smoothly transition to the new frequency. if aclki is not present, then the crystal oscillator of the jitter attenuator is forced to its center frequency. table 6 shows the status of rclk upon los. jitter attenuator the jitter attenuator reduces wander and jitter in the recovered clock signal. it consists of a 32-bit fifo, a crystal oscillator, a set of load capacitors for the crystal, and control logic. the jitter attenu- ator exceeds the jitter attenuation requirements of publications 43802 and rec. g.742. the jitter attenuator works in the following man- ner. the recovered clock and data are input to the fifo with the recovered clock controlling the fifos write pointer. the crystal oscillator con- trols the fifos read pointer which reads data out of the fifo and presents it at rpos and rneg (or rdata). the update rate of the read pointer is analogous to rclk. by changing the load ca- pacitance that the ic presents to the crystal, the oscillation frequency is adjusted to the average frequency of the recovered signal. logic deter- mines the phase relationship between the read and write pointers and decides how to adjust the load capacitance of the crystal. thus the jitter attenu- ator behaves as a first-order phase lock loop. jitter is absorbed in the fifo according to the jitter transfer characteristic shown in figure 12. crystal present? aclki present? source of rclk no yes aclki yes no centered crystal ye s ye s aclki via the jitter attenuator table 6. rclk status at los mode (pin 5) clke (pin 28) data clock clock edge for valid data low (<0.2v) x rpos rneg rclk rclk rising rising high (>(v+) - 0.2v) low rpos rneg sdo rclk rclk sclk rising rising falling high (>(v+) - 0.2v) high rpos rneg sdo rclk rclk sclk falling falling rising middle (2.5v) x rdata rclk falling x = don?t care table 5. data output/clock relationship cs61577 ds155pp2 13
the fifo in the jitter attenuator is designed to prevent overflow and underflow. if the jitter am- plitude becomes very large, the read and write pointers may get very close together. should they attempt to cross, the oscillators divide by four circuit adjusts by performing a divide by 3 1/2 or divide by 4 1/2 to prevent the overflow or under- flow. during this activity, data will never be lost. the 32-bit fifo in the cs61577 attenuator al- lows it to absorb jitter with minimum data delay in t1 and e1 switching or transmission applica- tions. like the cs61574, the cs61577 will tolerate large amplitude jitter (>23 uipp) by tracking rather than attenuating it, preventing data errors so that the jitter may be absorbed in exter- nal frame buffers. the jitter attenuator may be bypassed by pulling xtalin to rv+ through a 1 k w resistor and pro- viding a 1.544 mhz (or 2.048 mhz) clock on aclki. rclk may exhibit quantization jitter of approximately 1/13 uipp and a duty cycle of ap- proximately 30% (70%) when the attenuator is disabled. local loopback local loopback is selected by taking lloop, pin 27, high or by setting the lloop register bit via the serial interface. the local loopback mode takes clock and data presented on tclk, tpos, and tneg (or tdata), sends it through the jitter attenuator and outputs it at rclk, rpos and rneg (or rdata). if the jitter attenuator is disabled, it is bypassed. inputs to the transmitter are still trans- mitted on ttip and tring, unless taos has been selected in which case, ami-coded continu- ous ones are transmitted at the tclk frequency. the receiver rtip and rring inputs are ignored when local loopback is in effect. remote loopback remote loopback is selected by taking rloop, pin 26, high or by setting the rloop register bit via the serial interface. in remote loopback, the recovered clock and data input on rtip and rring are sent through the jitter attenuator and back out on the line via ttip and tring. selecting remote loopback overrides any taos request (see table 6). the recovered incoming signals are also sent to rclk, rpos and rneg (or rdata). a remote loopback oc- curs in response to rloop going high. attenuation in db frequency in hz 0 10 20 30 40 50 60 110 100 1 k 10 k b) maximum attenuation limit 62411 requirements a) minimum attenuation limit measured performance figure 12. typical jitter transfer function rloop input signal tao s input signal source of data for ttip & tring source of clock for ttip & tring 00 tdata tclk 0 1 all 1s tclk 1 x rtip & rring rtip & rring (rclk) notes: 1. x = don?t care. the identified all ones select input is ignored when the indicated loopback is in effect. 2. logic 1 indicates that loopback or all ones option is selected. table 7. interaction of rloop with taos cs61577 14 ds155pp2
simultaneous selection of local and remote loop- back modes is not valid (see reset). in the extended hardware mode the transmitted data is looped before the ami/b8zs/hdb3 en- coder/decoder during remote loopback so that the transmitted signal matches the received signal, even in the presence of received bipolar viola- tions. data output on rdata is decoded, however, if rcode is low. alarm indication signal in the extended hardware mode, the receiver sets the output pin ais high when less than 3 zeros are detected out of 2048 bit periods. line code encoder/decoder in the extended hardware mode, three line codes are available: ami, b8zs and hdb3. the input to the encoder is tdata. the outputs from the decoder are rdata and bpv (bipolar violation strobe). the encoder and decoder are selected using the len2, len1, len0, tcode and rcode pins as shown in table 8. parallel chip select in the extended hardware mode, pcs can be used to gate the digital control inputs: tcode, rcode, len0, len1, len2, rloop, lloop and taos. inputs are accepted on these pins only when pcs is low and will immediately change the operating state of the device. therefore, when cycling pcs to update the operating state, the digital control inputs should be stable for the en- tire pcs low period. the digital control inputs are ignored when pcs is high driver performance monitor to aid in early detection and easy isolation of non-functioning links, the ic is able to monitor transmit drive performance and report when the driver is no longer operational. this feature can be used to monitor either the devices perform- ance or the performance of a neighboring driver. the driver performance monitor indicator is nor- mally low, and goes high upon detecting a driver failure. the driver performance monitor consists of an ac- tivity detector that monitors the transmitted signal when mtip is connected to ttip and mring is connected to tring. dpm will go high if the absolute difference between mtip and mring does not transition above or below a threshold level within a time-out period. in the host mode, dpm is available from the register and pin 11. whenever more than one line interface ic resides on the same circuit board, the effectiveness of the driver performance monitor can be maximized by having each ic monitor performance of a neigh- boring ic, rather than having it monitor its own performance. note that a cs61577 can not be used to monitor a cs61574 due to output stage differences. len 2/1/0 000 010-111 tcode (transmit encoder selection) low hdb3 encoder b8zs encoder high ami encoder rcode (receiver decoder selection) low hdb3 decoder b8zs decoder high ami decoder table 8. encoder/decoder selection cs61577 ds155pp2 15
serial interface in the host mode, pins 23 through 28 serve as a microprocessor/microcontroller interface. one on-board register can be written to via the sdi pin or read from via the sdo pin at the clock rate determined by sclk. through this register, a host controller can be used to control operational characteristics and monitor device status. the se- rial port read/write timing is independent of the system transmit and receive timing. data transfers are initiated by taking the chip se- lect input, cs, low ( cs must initially be high). address and input data bits are clocked in on the rising edge of sclk. the clock edge on which output data is stable and valid is determined by clke as shown in table 5. data transfers are ter- minated by setting cs high. cs may go high no sooner than 50 ns after the rising edge of the sclk cycle corresponding to the last write bit. for a serial data read, cs may go high any time to terminate the output. figure 13 shows the timing relationships for data transfers when clke = 1. when clke = 1, data bit d7 is held until the falling edge of the 16th clock cycle. when clke = 0, data bit d7 is held until the rising edge of the 17th clock cycle. sdo goes high-z after cs goes high or at the end of the hold period of data bit d7. an address/command byte, shown in table 9, pre- cedes a data register. the first bit of the address/command byte determines whether a read or a write is requested. the next six bits contain the address. the line interface responds to address 16 (0010000). the last bit is ignored. the data register, shown in table 10, can be writ- ten to the serial port. data is input on the eight clock cycles immediately following the ad- dress/command byte. bits 0 and 1 are used to clear an interrupt issued from the int pin, which occurs in response to a loss of signal or a problem with the output driver. cs sclk sdo sdi d6 d5 d4 d3 d2 d1 d0 d7 0 0 d7 d6 d5 d4 d3 d2 d1 d0 address/command byte data input/output 0 0 0 1 0 r/w figure 13. input/output timing lsb, first bit 0 r/ w read/write select; 0 = write, 1 = read 1 add0 lsb of address, must be 0 2 add1 must be 0 3 add2 must be 0 4 add3 must be 0 5 add4 must be 1 6 - reserved - must be 0 table 9. address/command byte lsb: first bit in 0 clr los clear loss of signal 1 clr dpm clear driver performance monitor 2 len0 bit 0 - line length select 3 len1 bit 1 - line length select 4 len2 bit 2 - line lenght select 5 rloop remote loopback 6 lloop local loopback msb: last bit in 7 taos transmit all ones select note: setting 5, 6, & 7 to 101 or 111 puts the cs61577 into a factory test mode. table 10. input data register cs61577 16 ds155pp2
writing a "1" to either "clear los" or "clear dpm" over the serial interface has three effects: 1) the current interrupt on the serial interface will be cleared. (note that simply reading the register bits will not clear the inter- rupt). 2) output data bits 5, 6 and 7 will be reset as appropriate. 3) future interrupts for the corresponding los or dpm will be prevented from occurring. writing a "0" to either "clear los" or "clear dpm" enables the corresponding interrupt for los or dpm. input bits 5/6/7=111 and 5/6/7=101 are the same request, and cause the line interface to enter into the factory test mode. in other words, when rloop=1 (bit 5) and taos=1 (bit 7), loop (bit 6) is a dont care. for normal operation, rloop and taos should not be simultaneously selected via the serial interface. output data from the serial interface is presented as shown in tables 11 and 12. bits 2, 3 and 4 can be read to verify line length selection. bits 5, 6 and 7 must be decoded. codes 101, 110 and 111 (bits 5, 6 and 7) indicate intermittent losses of signal and/or driver problems. sdo goes to a high impedance state when not in use. sdo and sdi may be tied together in appli- cations where the host processor has a bi-directional i/o port. power on reset / reset upon power-up, the ic is held in a static state until the supply crosses a threshold of approxi- mately 3 volts. when this threshold is crossed, the device will delay for about 10 ms to allow the power supply to reach operating voltage. after this delay, calibration of the delay lines used in the transmit and receive sections commences. the delay lines can be calibrated only if a reference clock is present. the reference clock for the re- ceiver is provided by the crystal oscillator, or aclki if the oscillator is disabled. the reference clock for the transmitter is provided by tclk. the initial calibration should take less than 20 ms. in operation, the delay lines are continuously cali- brated, making the performance of the device independent of power supply or temperature vari- ations. the continuous calibration function forgoes any requirement to reset the line interface when in operation. however, a reset function is available which will clear all registers. in the hardware and extended hardware modes, a reset request is made by simultaneously setting both the rloop and lloop pins high for at least 200 ns. reset will initiate on the falling edge of the reset request (falling edge of rloop and lloop). in the host mode, a reset is initiated by simultaneously writing rloop and lloop to lsb: first bit in 0 los loss of signal 1 dpm driver performance monitor 2 len0 bit 0 - line length select 3 len1 bit 1 - line length select 4 len2 bit 2 - line lenght select table 11. output data bits 0 - 4 bits status 567 0 0 0 reset has occurred or no program input. 001taos in effect. 0 1 0 lloop in effect. 0 1 1 taos/lloop in effect. 1 0 0 rloop in effect 1 0 1 dpm changed state since last "clear dpm" occured. 1 1 0 los changed state since last "clear los" occured. 1 1 1 los and dpm have changed state since last "clear los" and "clear dpm". table 12. coding for serial output bits 5,6,7 cs61577 ds155pp2 17
the register. in either mode, a reset will set all reg- isters to 0 and force the oscillator to its center frequency before initiating calibration. a reset will also set los high. power supply the device operates from a single +5 volt supply. separate pins for transmit and receive supplies provide internal isolation. these pins should be connected externally near the device and decou- pled to their respective grounds. tv+ must not exceed rv+ by more than 0.3v. decoupling and filtering of the power supplies is crucial for the proper operation of the analog cir- cuits in both the transmit and receive paths. a 1.0 m f capacitor should be connected between tv+ and tgnd, and a 0.1 m f capacitor should be con- nected between rv+ and rgnd. use mylar or ceramic capacitors and place them as closely as possible to their respective power supply pins. a 68 m f tantalum capacitor should be added close to the rv+/rgnd supply. wire-wrap bread- boarding of the line interface is not recommended because lead resistance and inductance serve to defeat the function of the decoupling capacitors. schematic & layout review service confirm optimum schematic & layout before building your board. for our free review service call applications engineering. call: (512) 445-7222 cs61577 18 ds155pp2
pin descriptions hardware mode extended hardware mode top view 22 20 24 19 21 23 25 327 2 426 28 1 12 14 16 18 13 15 17 8 6 10 5 7 9 11 aclki tclk taos tpos lloop tneg rloop mode len2 rneg len1 rpos len0 rclk rgnd xtalin rv+ xtalout rring dpm rtip los mring ttip mtip tgnd tring tv+ 1 2 3 4 5 6 7 8 9 10 11 12 14 13 28 27 26 25 24 23 22 21 20 19 18 17 16 15 aclki taos tclk lloop tpos rloop tneg len2 mode len1 rneg len0 rpos rgnd rclk rv+ xtalin rring xtalout rtip dpm mring los mtip ttip tring tgnd tv+ cs61577 ds155pp2 19
host mode 1 2 3 4 5 6 7 8 9 10 11 12 14 13 28 27 26 25 24 23 22 21 20 19 18 17 16 15 top view 22 20 24 19 21 23 25 327 2 426 28 1 12 14 16 18 13 15 17 8 6 10 5 7 9 11 aclki clke tclk sclk tpos cs tneg sdo mode sdi rneg int rpos rgnd rclk rv+ xtalin rring xtalout rtip dpm mring los mtip ttip tring tgnd tv+ aclki tclk clke tpos sclk tneg cs mode sdo rneg sdi rpos int rclk rgnd xtalin rv+ xtalout rring dpm rtip los mring ttip mtip tgnd tring tv+ cs61577 20 ds155pp2
power supplies rgnd - ground, pin 22. power supply ground for all subcircuits except the transmit driver; typically 0 volts. rv+ - power supply, pin 21. power supply for all subcircuits except the transmit driver; typically +5 volts. tgnd - ground, transmit driver, pin 14. power supply ground for the transmit driver; typically 0 volts. tv+ - power supply, transmit driver, pin 15. power supply for the transmit driver; typically +5 volts. tv+ must not exceed rv+ by more than 0.3 v. oscillator xtalin, xtalout - crystal connections, pins 9 and 10. a 6.176 mhz (or 8.192 mhz) crystal should be connected across these pins. if a 1.544 mhz (or 2.048 mhz) clock is provided on aclki (pin 1), the jitter attenuator may be disabled by tying xtalin, pin 9 to rv+ through a 1 k w resistor, and floating xtalout, pin 10. overdriving the oscillator with an external clock is not supported. control aclki - alternate external clock input, pin 1. a 1.544 mhz (or 2.048 mhz) clock may be input to aclki, or this pin must be tied to ground. during los, the aclki input signal, if present, is output on rclk through the jitter attenuator. clke - clock edge, pin 28. (host mode) setting clke to logic 1 causes rpos and rneg to be valid on the falling edge of rclk, and sdo to be valid on the rising edge of sclk. conversely, setting clke to logic 0 causes rpos and rneg to be valid on the rising edge of rclk, and sdo to be valid on the falling edge of sclk. cs - chip select, pin 26. (host mode) this pin must transition from high to low to read or write the serial port. int - receive alarm interrupt, pin 23. (host mode) goes low when los or dpm change state to flag the host processor. int is cleared by writing "clear los" or "clear dpm" to the register. int is an open drain output and should be tied to the power supply through a resistor. cs61577 ds155pp2 21
len0, len1, len2 - line length selection, pins 23, 24 and 25. (hardware and extended hardware modes) determines the shape and amplitude of the transmitted pulse to accommodate several cable types and lengths. see table 3 for information on line length selection. also controls the receiver slicing level and the line code in extended hardware mode. lloop - local loopback, pin 27. (hardware and extended hardware modes) setting lloop to a logic 1 routes the transmit clock and data through the jitter attenuator to the receive clock and data pins. tclk and tpos/tneg (or tdata) are still transmitted unless overridden by a taos request. inputs on rtip and rring are ignored. mode - mode select, pin 5. driving the mode pin high puts the line interface in the host mode. in the host mode, a serial control port is used to control the line interface and determine its status. grounding the mode pin puts the line interface in the hardware mode, where configuration and status are controlled by discrete pins. floating the mode pin or driving it to +2.5 vselects the extended hardware mode, where configuration and status are controlled by discrete pins. when floating mode, there should be no external load on the pin. mode defines the status of 13 pins (see table 2). pcs - parallel chip select, pin 18. (extended hardware mode) setting pcs high causes the line interface to ignore the tcode, rcode, len0, len1, len2, rloop, lloop and taos inputs. rcode - receiver decoder select, pin 17. (extended hardware mode) setting rcode low enables b8zs or hdb3 zero substitution in the receiver decoder. setting rcode high enables the ami receiver decoder (see table 8). rloop - remote loopback, pin 26. (hardware and extended hardware modes) setting rloop to a logic 1 causes the recovered clock and data to be sent through the jitter attenuator (if active) and through the driver back to the line. the recovered signal is also sent to rclk and rpos/rneg (or rdata). any taos request is ignored. in the host mode, simultaneous selection of rloop & taos enables a factory test mode. simultaneously taking rloop and lloop high for at least 200 ns initiates a device reset. sclk - serial clock, pin 27. (host mode) clock used to read or write the serial port registers. sclk can be either high or low when the line interface is selected using the cs pin. sdi - serial data input, pin 24. (host mode) data for the on-chip register. sampled on the rising edge of sclk. sdo - serial data output, pin 25. (host mode) status and control information from the on-chip register. if clke is high sdo is valid on the rising edge of sclk. if clke is low sdo is valid on the falling edge of sclk. this pin goes to a high-impedance state when the serial port is being written to or after bit d7 is output. cs61577 22 ds155pp2
taos - transmit all ones select, pin 28. (hardware and extended hardware modes) setting taos to a logic 1 causes continuous ones to be transmitted at the frequency determined by tclk. in the host mode, simultaneous selection of rloop & taos enables a factory test mode. tcode - transmitter encoder select, pin 4. (extended hardware mode) setting tcode low enables b8zs or hdb3 zero substitution in the transmitter encoder. setting tcode high enables the ami transmitter encoder . data rdata - receive data - pin 7. (extended hardware mode) data recovered from the rtip and rring inputs is output at this pin, after being decoded by the line code decoder. rdata is nrz. rdata is stable and valid on the falling edge of rclk. rclk - recovered clock, pin 8. the receiver recovered clock generated by the jitter attenuator is output on this pin.when in the loss of signal state aclki (if present) is output on rclk via the jitter attenuator. if aclki is not present during los, rclk is forced to the center frequency of the crystal oscillator.. rpos, rneg - receive positive data, receive negative data, pins 6 and 7. (hardware and host modes) the receiver recovered nrz digital data is output on these pins. in the hardware mode, rpos and rneg are stable and valid on the rising edge of rclk. in the host mode, clke determines the clock edge for which rpos and rneg are stable and valid. see table 5. a positive pulse (with respect to ground) received on the rtip pin generates a logic 1 on rpos, and a positive pulse received on the rring pin generates a logic 1 on rneg. rtip, rring - receive tip, receive ring, pins 19 and 20. the ami receive signal is input to these pins. a center-tapped, center-grounded, 2:1, step-up transformer is required on these inputs, as shown in figure a1 in the applications section. data and clock are recovered and output on rclk and rpos/rneg or rdta. tclk - transmit clock, pin 2. the1.544 mhz (or 2.048 mhz) transmit clock is input on this pin. tpos/tneg or tdata are sampled on the falling edge of tclk. tdata - transmit data, pin 3. (extended hardware mode) transmitter nrz input data which passes through the line code encoder, and is then driven on to the line through ttip and tring. tdata is sampled on the falling edge of tclk. tpos, tneg - transmit positive data, transmit negative data, pins 3 and 4. (hardware and host modes) inputs for clock and data to be transmitted. the signal is driven on to the line through ttip and tring. tpos and tneg are sampled on the falling edge of tclk. a tpos input causes a positive pulse to be transmitted, while a tneg input causes a negative pulse to be transmitted. cs61577 ds155pp2 23
ttip, tring - transmit tip, transmit ring, pins 13 and 16. the ami signal is driven to the line through these pins. the transmitter output is designed to drive a 25 w load between ttip and tring. a transformer is required as shown in table a1. status ais - alarm indication signal, pin 11. (extended hardware mode) ais goes high when unframed all-ones condition (blue alarm) is detected, using the detection criteria of less than three zeros out of 2048 bit periods. bpv- bipolar violation strobe, pin 6. (extended hardware mode) bpv strobes high when a bipolar violation is detected in the received signal. b8zs (or hdb3) zero substitutions are not flagged as bipolar violations if the b8zs (or hdb3) decoder has been enabled. dpm - driver performance monitor, pin 11. (hardware and host modes) dpm goes high if no activity is detected on mtip and mring. los - loss of signal, pin 12. los goes high when 175 consecutive zeros have been received. los returns low when 3 ones are received within 32 bit periods with no more than 15 consecutive zeros. when in the loss of signal state rpos/rneg or rdata are forced low, and aclki (if present) is output on rclk via the jitter attenuator. if aclki is not present during los, rclk is forced to the center frequency of the crystal oscillator. mtip, mring - monitor tip, monitor ring, pins 17 and 18. (hardware and host modes) these pins are normally connected to ttip and tring and monitor the output of a line interface ic. if the int pin in the host mode is used, and the monitor is not used, writing "clear dpm" to the serial interface will prevent an interrupt from the driver performance monitor. cs61577 24 ds155pp2
28 pin plastic dip 1 28 15 14 millimeters inches dim minmaxminmax d b a l c 13.72 14.22 0.540 0.560 36.45 1.02 0.36 0.51 3.94 3.18 0.20 0 15.24 37.21 1.65 0.56 1.02 5.08 3.81 0.38 15 1.435 0.040 0.014 0.020 0.155 0.125 0.600 0.008 0 1.465 0.065 0.022 0.040 0.200 0.150 0.015 15 15.87 0.625 2.41 2.67 0.095 0.105 c ea e1 d b seating plane a b1 e1 a1 l notes: 1. positional tolerance of leads shall be within 0.25mm (0.010") at maximum material condition, in relation to seating plane and each other. 2. dimension ea to center of leads when formed parallel. 3. dimension e1 does not include mold flash. nom 13.97 36.83 1.27 0.46 0.76 4.32 - 0.25 - - 2.54 nom 0.550 1.450 0.050 0.018 0.030 0.170 - - 0.010 - 0.100 a1 b1 e1 e1 ea e e1 d1 d d2/e2 28-pin plcc 28 d2/e2 max min max min millimeters inches dim a 4.57 4.20 0.180 0.165 d/e 12.32 12.57 0.485 0.495 b 0.53 0.33 0.021 0.013 e a a1 b e 2.29 0.090 11.43 11.58 0.450 0.456 9.91 10.92 0.390 0.430 1.19 1.35 0.047 0.053 nom 4.45 12.45 0.41 2.79 11.51 10.41 1.27 nom 0.175 0.490 0.016 0.110 0.453 0.410 0.050 3.04 0.120 d1/e1 a1 cs61577 ds155pp2 25
applications line interface figures a1-a3 show typical t1 and e1 line inter- face application circuits. table a1 shows the external components which are specific to each application. figure a1 illustrates a t1 interface in the host mode. figure a2 illustrates a 120 w e1 interface in the hardware mode. figure a3 illus- trates a 75 w e1 interface in the extended hardware mode. the 1:2 receiver transformer has a grounded cen- ter tap on the ic side. resistors r1 and r2 between the rtip and rring pins to ground provide the termination for the receive line. the transmitter also uses a 1:2 transformer. a 0.47 m f capacitor is required in series with the transmit transformer primary. this capacitor is needed to prevent any output stage imbalance from resulting in a dc current through the transformer primary. this current might saturate the transformer pro- ducing an output offset level shift. control & monitor frame format encoder/ decoder cs61577 in host mode receive line transmit line 28 1 12 11 5 7 6 8 3 4 2 9 10 xtl rv+ + 68 m f rgnd 0.1 m f +5v 21 15 + 1.0 m f tgnd rv+ tv+ clke aclki los dpm mode rpos rneg rclk tpos tneg tclk xtalin xtalout rgnd tgnd 22 14 sclk cs int sdi sdo rtip rring mtip mring tring ttip 19 20 17 18 16 13 r1 r2 1 3 5 2 6 0.47 m f 2 6 1 5 1:2ct pe-65351 2ct:1 pe-65351 m p serial port 27 26 23 24 25 +5v 100 k w figure a1. t1 host mode configuration frequency mhz crystal xtl cable w len2/1/0 r3 w r1 and r2 w 1.544 (t1) cxt6176 100 0/1/1 - 1/1/1 not used 200 2.048 (e1) cxt8192 120 0/0/0 not used 240 75 0/0/0 4.4 150 0/0/1 not used table a1. external component values cs61577 26 ds155pp2
control & monitor frame format encoder/ decoder cs61577 in hardware mode line length setting receive line transmit line 28 1 26 27 5 7 6 8 3 4 2 9 10 xtl + 68 m f rgnd 0.1 m f +5v 21 15 + 1.0 m f tgnd rv+ tv+ taos aclki rloop lloop mode rpos rneg rclk tpos tneg tclk xtalin xtalout rgnd tgnd 22 14 len0 len1 len2 rtip rring mtip mring tring ttip 23 24 25 19 20 17 18 16 13 r1 r2 1 3 5 2 6 0.47 m f 2 6 1 5 1:2ct pe-65351 2ct:1 pe-65351 12 11 los dpm figure a2. 120 w, e1 hardware mode configuration control & monitor frame format encoder/ decoder cs61577 in extended hardware mode line length setting receive line transmit line 17 18 6 28 5 7 8 3 2 9 10 xtl + 68 m f rgnd 0.1 m f +5v 21 15 + 1.0 m f tgnd rv+ tv+ rcode pcs bpv taos mode rdata rclk tdata tclk xtalin xtalout rgnd tgnd 22 14 len0 len1 len2 rtip rring tring ttip 23 24 25 19 20 16 13 r1 r2 1 3 5 2 6 0.47 m f 2 6 1 5 1:2ct pe-65351 2ct:1 pe-65351 1 26 aclki rloop 27 12 lloop los 11 ais 4 tcode r3 note: r3 is used for len2/1/0 = 0/0/0, but not required with len2/1/0 = 0/0/1. figure a3. 75 w, e1 extended hardware mode configuration cs61577 ds155pp2 27
transformers recommended transmitter and receiver trans- former specifications are shown in table a2. the transformers in table a3 have been tested and recommended for use with the cs61577. refer to the "telecom transformer selection guide" for detailed schematics which show how to connect the line interface ic with a particular transformer. selecting an oscillator crystal specific crystal parameters are required for proper operation of the jitter attenuator. it is rec- ommended that the crystal semiconductor cxt6176 crystal be used for t1 applications and the cxt8192 crystal be used for e1 applications. transmit side jitter attenuation in some applications it is desirable to attenuate jitter from the signal to be transmitted. a cs61577 in local loopback mode can be used as a jitter attenuator. the inputs to the jitter attenuator are tpos, tneg, tclk. the outputs from the jitter attenuator are rpos, rneg and rclk. line protection secondary protection components can be added to provide lightning surge and ac power-cross immunity. refer to the "telecom line protection application note" for detailed information on the different electrical safety standards and specific application circuit recommendations. turns ratio 1:2 ct 5% primary inductance 600 m h min. @ 772 khz primary leakage inductance 1.3 m h max. @ 772 khz secondary leakage inductance 0.4 m h max. @ 772 khz interwinding capacitance 23 pf max. et-constant 16 v- m s min. for t1 12 v- m s min. for e1 table a2. transformer specifications tu r n s ratio(s) manufacturer part number package type 1:2ct pulse engineering pe-65351 1.5 kv through-hole, single schott 67129300 bel fuse 0553-0013-hc dual 1:2ct pulse engineering pe-64951 1.5 kv through-hole, dual bel fuse 0553-0013-1j dual 1:2ct pulse engineering pe-65761 1.5 kvsurface-mount, dual bel fuse s553-0013-03 1:2ct pulse engineering pe-65835 3 kv through-hole, single en60950, en41003 approved table a3. recommended transformers cs61577 28 ds155pp2
interfacing the cs61577 with the cs62180b t1 transceiver to interface with the cs62180b, connect the de- vices as shown in figure a5. in this case, the line interface and cs62180b are in host mode con- trolled by a microprocessor serial interface. if the line interface is used in hardware mode, then the line interface rclk output must be inverted be- fore being input to the cs62180b. if the cs61577 is used in extended hardware mode, the rclk output does not have to be inverted be- fore being input to the cs62180b. aclk tclk rclk rpos rneg tpos tneg cs62180b clke sclk int sdo sdi tclk tpos tneg rneg rpos rclk sclk sdo sdi to host controller v+ 100k 1.544 mhz clock signal cs61577 cs cs v+ 22k mode figure a4. interfacing the cs61577 with a cs62180b (host mode) cs61577 ds155pp2 29
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features socketed line interface device all required components for complete line interface evaluation configuration by dip switch or serial interface led status indicators for alarm conditions support for host, hardware, and extended hardware modes general description the evaluation board includes a socketed line interface device and all support components necessary for evaluation. the board is powered by an external 5 volt supply. the board may be configured for 100 w twisted-pair t1, 75 w coax e1, or 120 w twisted-pair e1 operation. binding posts are provided for line connections. sev- eral bnc connectors are available to provide system clocks and data i/o. two led indicators monitor de- vice alarm conditions. the board supports all line interface operating modes. ordering information: cdb61534, cdb61535. cdb61535a, cdb6158, cdb6158a, cdb61574, cdb61574a, cdb61575, cdb61577, cdb61304a, cdb61305a sep 95 ds40db3 31 crystal semiconductor corporation p.o. box 17847, austin, tx 78760 (512) 445-7222 fax: (512) 445-7581 line interface evaluation board cdb61534, cdb61535, cdb61535a, cdb6158, cdb6158a, cdb61574, cdb61574a, cdb61575, cdb61577, cdb615304a, & cdb61305a aclki tclk tpos (tdata) tneg rneg (bpv) rpos (rdata) rclk cs61534, cs61535, cs61535a, cs6158, cs6158a, cs61574, cs61574a, cs61575, cs61577, cs61304a or cs61305a reset circuit mode select circuit (tcode) +5v 0v led status indicators hardware control circuit serial interface control circuit ttip tring rtip rring xtl
power supply as shown on the evaluation board schematic in figure 1, power is supplied to the evaluation board from an external +5 volt supply connected to the two binding posts labeled +5v and gnd. transient suppressor d10 protects the compo- nents on the board from over-voltage damage and reversed supply connections. the recommended power supply decoupling is provided by c1, c2 and c3. ceramic capacitor c1 and electrolytic ca- pacitor c2 are used to decouple rv+ to rgnd. capacitor c3 decouples tv+ to tgnd. the tv+ and rv+ power supply traces are connected at the device socket u1. a ground plane on the compo- nent side of the evaluation board insures optimum performance. board configuration pins on line interface device u1 with more than one pin name have different functions depending on the operating mode selected. pin names not enclosed in parenthesis or square brackets de- scribe the hardware mode pin function. pin names enclosed in parenthesis describe the ex- tended hardware mode pin function. pin names enclosed in square brackets describe the host mode pin function. table 1 explains how to configure the evaluation board jumpers depending on the device installed and the desired operating mode. mode selection is accomplished with slide switch sw1 and jump- ers jp2, jp6, and jp7. the cs61535a, cs61574a, cs61575, cs61577, cs61304a, and cs61305a support the hardware, extended hardware, and host operating modes. the cs61534, cs61535, and cs61574 support the hardware and host operating modes. the cs6158 and cs6158a only support the hardware operating mode. hardware mode in the hardware operating mode, the line inter- face is configured using dip switch s2. the digi- tal control inputs to the device selected by s2 in- clude: transmit all ones (taos), local loopback (lloop), remote loopback (rloop), and trans- mit line length selection (len2,len1,len0). closing a dip switch on s2 towards the label sets the device control pin of the same name to logic 1 (+5 volts). note that s2 switch positions tcode and rcode have no function in hardware mode. in addition, the host processor interface connector jp1 should not be used in the hardware mode. two led status indicators are provided in hard- ware mode. the led labeled dpm (ais) illumi- nates when the line interface asserts the driver jumper position function selected jp1 - connector for external processor in host operating mode. jp2, jp6, jp7 a-a extended hardware operating mode. b-b hardware or host operating modes. jp3 in hardware or extended hardware operating modes. out host operating mode. jp4 c-c connects the aclki bnc input to pin 1 of device. d-d grounds the aclki bnc input through 51 w resistor r1. jp5 e-e transmit line connection for all applications except those listed for "f-f" on the next line. f-f 75 w coax e1 applications using the schott 12932/12532 or pe-65389/65566 at transformer t1. jp8 in shorts resistor r2 for all applications except those listed for "out" on the next line. out inserts resistor r2 for 75 w coax e1 applications using the cs61534, 35, 58, 74, or 77. table 1. evaluation board jumper settings line interface evaluation board 32 ds40db3
r16 1k w 8 rclk 2 tclk 3 tpos (tdata) 6 rneg (bpv) pin 3 tclk rclk pin 6 4 tneg 7 rpos (rdata) 1 aclki pin 7 aclki r1 51.1 w pin 4 s2 r15 100 w rv+ jp3 rv+ q1 2n2222 r6 470 w led d3 rv+ q2 2n2222 r5 470 w led d2 jp1 d9 1n914 d8 r14 4.7k w sip rv+ los dpm (ais) mode r18 10k w r17 10k w 511 12 23 24 25 26 27 28 len1/sdi len2/sd0 lloop/sclk taos/clke tcode rloop/cs sdi sdo sclk int cs len0/int s1 reset mode sw1 r4 221k w a a bb dd c c jp4 jp2 rcode c4 0.047 m f 3 6 875124 host:3-1,6-8 ext hw: 3-2, 6-7 hw: 3-4, 6-5 18 tring ttip 0.47 m f c5 tring ttip +5v 22 14 15 rv+ tv+ tgnd rgnd d10 p6ke 21 t1 (see table 2) 17 c2 0.1 m f c1 68 m f 19 rtip rring rring rtip 20 jp8 r2 4.4 w c3 1 m f rv+ rclk tclk rneg (bpv) aclki len1 [sdi] len2 [sd0] lloop [sclk] taos [ckle] xtalin {cs6158/58a: rt} xtalout {cs6158/58a: nc} los dpm (ais) mode 13 16 aa aa b b bb rtip rring tring pin 17 pin 18 9 10 ttip rv+ r13 (only included for cs6158/58a) 1k w (used only for e1 75 w applications with the cs61534, cs61535, cs6158, cs61574, or cs61577) cs61534, cs61535, cs61535a, cs6158, cs6158a, cs61574, cs61574a, cs61575, cs61577, cs61304a, or cs61305a u1: f f e e prototyping area rv+ len0 [int] rloop [cs] mring (pcs) rpos (rdata) tpos (tdata) mtip (rcode) jp6 jp7 jp5 e1: cxt8192 t1: cxt6176 (not included for cs6158/58a) + tneg (tcode) u1 r9 200 w r10 200 w t2 (see table 2) 2:1 gnd (0v) change r9 and r10 for e1 operation figure 1. evaluation board schematic line interface evaluation board ds40db3 33
performance monitor alarm. the led labeled los illuminates when the line interface receiver has detected a loss of signal. extended hardware mode in the extended hardware operating mode, the line interface is configured using dip switch s2. the digital control inputs to the device selected by s2 include: transmit all ones (taos), local loopback (lloop), remote loopback (rloop), transmit line length selection (len2, len1, len0), transmit line code ( tcode), and receive line code ( rcode). closing a dip switch (mov- ing it towards the s2 label) sets the device control pin of the same name to logic 1 (+5 volts). note that the tcode and rcode options are active low and are enabled when the switch is moved away from the s2 label. the parallel chip select input pcs is tied to ground in extended hard- ware mode to enable the device to be reconfig- ured when s2 is changed. in addition, the host processor interface connector jp1 should not be used in extended hardware mode. two led status indicators are provided in ex- tended hardware mode. the led labeled dpm (ais) illuminates when the line interface detects the receive blue alarm (ais). the led labeled los illuminates when the line interface receiver has detected a loss of signal. host mode in the host operating mode, the line interface is configured using a host processor connected to the serial interface port jp1. the s2 switch posi- tion labeled clke selects the active edge of sclk and rclk. closing the clke switch se- lects rpos and rneg to be valid on the falling edge of rclk and sdo to be valid on the rising edge of sclk as required by the cs2180b t1 framer. all other dip switch positions on s2 should be open (logic 0) to prevent shorting of the serial in- terface signals. resistor r15 is a current limiting resistor that prevents the serial interface signals from being shorted directly to the +5 volt supply if any s2 switch, other than clke, is closed. jumper jp3 should be out so the int pin may be externally pulled-up at the host processor inter- rupt pin. two led status indicators are provided in host mode. the led labeled dpm (ais) illuminates when the line interface asserts the driver per- formance monitor alarm. the led labeled los illuminates when the line interface receiver has detected a loss of signal. manual reset a manual reset circuit is provided that can be used in hardware and extended hardware modes. the reset circuit consists of s1, r4, r16, c4, d8, and d9. pressing switch s1 forces both lloop and rloop to a logic 1 and causes a reset. a reset is only necessary for the cs61534 device to calibrate the center frequency of the re- ceiver clock recovery circuit. all other line inter- face units use a continuously calibrated clock re- covery circuit that eliminates the reset require- ment. transmit circuit the transmit clock and data signals are supplied on bnc inputs labeled tclk, tpos(tdata), and tneg. in the hardware and host operating modes, data is supplied on the tpos(tdata) and tneg connectors in dual nrz format. in the extended hardware operating mode, data is sup- plied in nrz format on the tpos(tdata) con- nector and tneg is not used. the transmitter output is transformer coupled to the line through a transformer denoted as t1 in figure 1. the signal is available at the ttip and tring binding posts. capacitor c5 is the recom- mended 0.47 m f dc blocking capacitor. line interface evaluation board 34 ds40db3
the evaluation board supports 100 w twisted-pair t1, 75 w coax e1, and 120 w twisted-pair e1 op- eration. the cdb61534, cdb61535, cdb6158, cdb61574, and cdb61577 are supplied from the factory with a 1:2 transmit transformer that may be used for all t1 and e1 applications. the cdb61535a, cdb6158a, cdb61574a, cdb61575, cdb61304a, and cdb61305a are supplied with a 1:1.15 transmit transformer in- stalled for t1 applications. an additional 1:1:1.26 transformer for e1 applications is provided with the board. this transformer requires jp5 to be jumpered across f-f for 75 w coax e1 applica- tions. the cdb61534, cdb61535, cdb6158, cdb61574, and cdb61577 require the jp8 jumper to be out for 75 w coax e1 applications. this inserts resistor r2 to reduce the transmit pulse amplitude and meet the 2.37 v nominal pulse amplitude requirement in ccitt g.703. in addition, r2 increases the equivalent load imped- ance across ttip and tring. receive circuit the receive line interface signal is input at the rtip and rring binding posts. the receive sig- nal is transformer coupled to the line interface de- vice through a center-tapped 1:2 transformer. the transformer produces ground referenced pulses of equal amplitude and opposite polarity on rtip and rring. the receive line interface is terminated by resis- tors r9 and r10. the evaluation boards are sup- plied from the factory with 200 w resistors for ter- minating 100 w t1 twisted-pair lines. resistors r9 and r10 should be replaced with 240 w resis- tors for terminating 120 w e1 twisted-pair lines or 150 w resistors for terminating 75 w e1 coaxial lines. two 243 w resistors and two 150 w resistors are included with the evaluation board for this purpose. the recovered clock and data signals are avail- able on bnc outputs labeled rclk, rpos(rdata), and rneg(bpv). in the hard- ware and host operating modes, data is output on the rpos(rdata) and rneg(bpv) connectors in dual nrz format. in the extended hardware operating mode, data is output in nrz format on the rpos(rdata) connector and bipolar viola- tions are reported on the rneg(bpv) connector. quartz crystal a quartz crystal must be installed in socket y1 for all devices except the cs6158 and cs6158a. a crystal semiconductor cxt6176 crystal is rec- ommended for t1 operation and a cxt8192 is recommended for e1 operation. the evaluation board has a cxt6176 installed at the factory and a cxt8192 is also provided with the board. the cdb6158 and cdb6158a have resistor r13 installed instead of a crystal. this connects the rt pin of the device to the +5 volt supply. alternate clock input the aclki bnc input provides the alternate clock reference for the line interface device (aclk for the cs61534) when jp4 is jumpered across c-c. this clock is required for the cs61534, cs61535, cs6158, and cs6158a op- eration but is optional for all other line interface devices. if aclki is provided, it may be desir- able to connect both c-c and d-d positions on jp4 to terminate the external clock source provid- ing aclki with the 51 w resistor r1. if aclki is optional and not used, connector jp4 should be jumpered across d-d to ground pin 1 of the de- vice through resistor r1. transformer selection to permit the evaluation of other transformers, table 2 lists the transformer and line interface de- vice combinations that can be used in t1 and e1 line interface evaluation board ds40db3 35
applications. a letter at the intersection of a row and column in table 2 indicates that the selected transformer is supported for use with the device. the transformer is installed in the evaluation board with pin 1 positioned to match the letter illustrated on the drawing in table 2. for exam- ple, the pulse engineering pe-65388 transformer may be used with the transmitter of the cs61575 device for 100 w t1 applications only (as indi- cated by note 3) when installed in transformer socket t1 with pin 1 at position d (upper right). prototyping area a prototyping area with power supply and ground connections is provided on the evaluation board. this area can be used to develop and test a vari- ety of additional circuits like a data pattern gener- ator, cs2180b framer, system synchronizer pll, or specialized interface logic. evaluation hints 1. properly terminate ttip/tring when evaluat- ing the transmit output signal. for more informa- tion concerning pulse shape evaluation, refer to the crystal application note entitled "measure- ment and evaluation of pulse shapes in t1/e1 transmission systems." 2. change the receiver terminating resistors r9 and r10 when evaluating e1 applications. resis- tors r9 and r10 should be replaced with 240 w resistors for terminating 120 w e1 twisted-pair lines or 150 w resistors for terminating 75 w e1 coaxial lines. two 243 w resistors and two 150 w resistors are included with the evaluation board for this purpose. 3. closing a dip switch on s2 towards the label sets the device control pin of the same name to logic 1 (+5 volts). 4. to avoid damage to the external host controller connected to jp1, all s2 switch positions (except clke) should be open. in the host operating mode, the clke switch selects the active edge of sclk and rclk. line interface evaluation board 36 ds40db3
notes: 1. a letter at the intersection of a row and column in table 2 indicates that the selected transformer is supported for use with the device. the transformer is installed in the evaluation board with pin 1 po- sitioned to match the letter illustrated in the drawing to the left. 2. the receive transformer (rx) is soldered at location t2 on the evaluation board and is used for all applications. the transmit transformer (tx) is socketed at location t1 on the evaluation board and may be changed according to the application. 3. for use in 100 w t1 twisted-pair applications only. 4. for use in 75 w and 120 w e1 applications only. place jumper jp5 in position f-f for 75 w e1 applications requiring a 1:1 turns ratio. 5. transmitter return loss improves when using a 1:2 turns ratio trans- former with the appropriate transmit resistors. table 2. transformer applications transformer (turns ratio) 1,2 line interface unit 34 35 35a 58 58a 74,77 74a 75 304a, 305a rx tx rx tx rx tx rx tx rx tx rx tx rx tx rx tx rx tx pe-65351 (1:2ct) a d a d a a d a a d a a a schott 12930 (1:2ct) b c b c b b c b b c b b b pe-65388 (1:1.15) d 3 d 3 d 3 d 3 d 3,5 schott 12931 (1:1.15) c 3 c 3 c 3 c 3 c 3,5 pe-65389 (1:1:1.26) d 4 d 4 d 4 d 4 d 4,5 schott 12932 (1:1:1.26) c 4 c 4 c 4 c 4 c 4,5 pe-64951 (dual 1:2ct) e e e e schott 11509 (dual 1:2ct) e e e e pe-65565 (dual 1:1.15 & 1:2ct) e 3 e 3 e 3 e 3 e 3,5 schott 12531 (dual 1:1.15 & 1:2ct) e 3 e 3 e 3 e 3 e 3,5 pe-65566 (dual 1:1:1.26 & 1:2ct) e 4 e 4 e 4 e 4 e 4,5 schott 12532 (dual 1:1:1.26 & 1:2ct) e 4 e 4 e 4 e 4 e 4,5 e t2 t1 d a c b t2 t1 line interface evaluation board ds40db3 37
figure 2. silk screen layer (not to scale) line interface evaluation board 38 ds40db3
figure 3. top ground plane layer (not to scale) line interface evaluation board ds40db3 39
figure 4. bottom trace layer (not to scale) line interface evaluation board 40 ds40db3
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