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preliminary motorola semiconductor technical data MC68176 order this document by: MC68176/d ?1997 motorola, inc. advance information this document contains information on a new product. specifications and information herein are subject to change without notice. MC68176 2-bit a/d converter ic the MC68176 chip is part of a total solution available from motorola for providing flex? paging capabilities in a low-power, low-cost system. working in conjunction with standard paging receivers, the MC68176 takes the 4-level baseband audio signals from the receiver and performs 2-bit a/d using 8-bit dacs for peak and valley detection, passing the 2-bit digital signal directly to the mc68175 flex chip or mc68181 roaming flex chip for further decoding and flex protocol handling. received messages are then passed to the host microcontroller or microprocessor via the serial peripheral interface (spi). the host processor (running flexstack? software) interprets the data appropriately (as binary, alphanumeric or numeric message types), and handles all i/o and user interaction functions. the flex paging protocol is the multi-speed, high-performance protocol adopted by leading service providers worldwide. flex protocol gives service providers the increased capacity, added reliability, and enhanced pager battery performance required today. it also provides an upward migration path to the service provider which is completely transparent to the end user. figure 1 MC68176 functional block diagram v add v ddd 1 khz / 2 khz scf charge pump ctr ctr 8-bit dac 8-bit dac v add sel bw adin dc-offset exts0 exts1 con1 con2 trkinh mode control & enable gnd s 2-bit adc aa0910 reserved
preliminary ii MC68176 technical data sheet motorola table of contents section 1 signal/connection descriptions . . . . . . . . . . . . . . . . . . 1-1 section 2 specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 section 3 packaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1 section 4 design considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1 section 5 ordering information . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1 appendix a description of operation. . . . . . . . . . . . . . . . . . . . . . . . . a-1 for technical assistance: telephone: 1-800-521-6274 email: dsphelp@dsp.sps.mot.com internet: http://www.motorola-dsp.com data sheet conventions t his data sheet uses the following conventions: overbar used to indicate a signal that is active when pulled low (for example, the reset pin is active when low.) asserted means that a high true (active high) signal is high or that a low true (active low) signal is low deasserted means that a high true (active high) signal is low or that a low true (active low) signal is high examples: signal/symbol logic state signal state voltage pin true asserted v il /v ol pin false deasserted v ih /v oh pin true asserted v ih /v oh pin false deasserted v il /v ol note: values for v il , v ol , v ih , and v oh are defined by individual product specifications.
features preliminary motorola MC68176 technical data sheet iii features ? 2-bit a/d converter ? supports flex protocol with the mc68175 and mc68181 flex decoder chips ? peak and valley 8-bit dac detectors compensate for signal strength variation ? pin-selectable 2-pole butterworth low pass filter C bw = 0: 1 khz 5% ( - 3 db) (for 1600 symbols/second) C bw = 1: 2 khz 5% ( - 3 db) (for 3200 symbols/second) ? 600 mv input voltage range @v add = 2.7 v and 1.8 v ?100 m a typical operating current @ v add =2.7v ? three modes of operation: C fast track mode C slow track mode C hold acquisition ? standby mode for low power consumption ? - 30 c to 85 c temperature range ? 2 v and 3 v operation 10% for both v ddd and v add ? flexible supply mode (i.e., v add can be at 2 v and v ddd can be at 3 v or vice-versa) ?for v add = 2 v, an internal charge pump is enabled to provide higher voltages for some analog circuits. ? 14-pin soic package additional support flex system software from motorola is a family of software components for building world- class products incorporating messaging capabilities. flexstack? software is specifically designed to support the flex chip ic. flexstack software runs on a product host processor and takes care of communicating with the flex chip ic and fully interpreting the codewords that are passed to the host from the flex chip ic. documentation this document is the primary document supporting the MC68176 flex 2-bit a/d. documentation is available from a local motorola distributor, a motorola semiconductor sales office, a motorola literature distribution center, or through the motorola dsp home page on the internet (the source for the latest information).
documentation preliminary iv MC68176 technical data sheet motorola
preliminary motorola MC68176 technical data sheet 1-1 section 1 signal/connection descriptions signal groupings the input and output signals of the MC68176 are organized into six functional groups, as shown in table 1-1 and as illustrated in figure 1-1 . figure 1-1 on page 1-2 is a diagram of MC68176 signals by functional group. table 1-1 MC68176 functional signal groupings functional group number of signals detailed description power and reserved signal 4 table 1-2 timing 1 table 1-3 analog inputs 2 table 1-4 analog controls 2 table 1-5 digital outputs 2 table 1-6 digital inputs 3 table 1-7
preliminary 1-2 MC68176 technical data sheet motorola signal/connection descriptions power power timing figure 1-1 signals identified by functional group table 1-2 power and reserved signal signal name description v add power v add is the input power for the analog portion of the ic. v ddd power v ddd is the input power for the digital portion of the ic. v ss ground v ss is ground connection for the ic. reserved reserved this pin must be connected to vss to ensure proper operation table 1-3 timing signal signal name type signal description clock input clock input this is a 38.4 khz 50% duty cycle clock, typically provided by clkout on the mc68175 flex chip or mc68181 roaming flex chip. MC68176 clock 38.4 khz v add v ddd v ss v add sel power analog input power digital input power ground analog inputs adin dc-offset bw analog input analog dc offset bandwidth select analog power supply/ current symbol msb current symbol lsb exts1 exts0 track inhibit mode trkinh con1 con2 configure 2 mode configure 1 aa1291 digital outputs digital inputs analog control analog gain select timing reserved
preliminary motorola MC68176 technical data sheet 1-3 signal/connection descriptions analog inputs analog inputs analog control table 1-4 analog input signals signal name type signal description adin input analog data in this is the 4-level baseband analog audio input signal to be digitized. dc-offset input dc offse tthis analog input signal is the dc content of the analog input signal adin. this pin needs a dc voltage (identical to the if dc voltage content) applied to it, to prevent clipping of the adin input signal. table 1-5 analog control signals signal name type signal description v add sel input v add select if v add is nominal 3 v, set v add sel to 0. if v add is nominal 2 v, set v add sel to 1. this signal has two functionsto enable a charge pump when v add is 2 v, and to control the analog gain of the filter stage. if v add sel is 1, the charge pump is enabled, ensuring parts of the analog circuit have a higher supply. v add sel also controls the gain of the filter stage: v add sel = 0: gain = 3.656 v add sel = 1: gain = 2.437 bw input bandwidth select this digital signal controls the cutoff frequency for the second-order low-pass butterworth or switched capacitor filter: bw = 0: 1 khz filter (for 1600 symbols/second) bw = 1: 2 khz filter (for 3200 symbols/second)
preliminary 1-4 MC68176 technical data sheet motorola signal/connection descriptions digital outputs digital outputs digital inputs note: all digital signals are latched on the falling edge of clock except v add sel. table 1-6 digital output signals signal name signal type signal description exts0C1 output digitized output bits these are the gray-scale encoded digitized representation of adin. the transition levels are relative to the measured peak and valley signal levels. exts0 = 1, exts1 = 0: 5/6 < adin < 1 exts0 = 1, exts1 = 1: 1/2 < adin < 5/6 exts0 = 0, exts1 = 1: 1/6 < adin < 1/2 exts0 = 0, exts1 = 0: 0 < adin < 1/6 table 1-7 digital input signals signal name signal type signal description con0C1 input mode configuration con0 and con1 specify the mode of operation for the MC68176. con0 = 0, con1 = 0: lower power standby mode con0 = 0, con1 = 1: fast track mode con0 = 1, con1 = 0: hold mode con0 = 1, con1 = 1: slow track mode trkinh input track inhibit this signal controls the operation of the peak and valley audio signal strength detectors. trkinh is synchronized with the falling edge of clock. trkinh = 0: enables peak and valley counters and enables decay. trkinh = 1: disables peak and valley counters and disables decay.
preliminary motorola MC68176 technical data sheet 2-1 section 2 specifications introduction the MC68176 is fabricated in high density cmos with transistor-transistor logic (ttl) compatible inputs and outputs. the MC68176 specifications are preliminary and are from design simulations, and may not be fully tested or guaranteed at this early stage of the product life cycle. finalized specifications will be published after full characterization and device qualifications are complete. maximum ratings caution this device contains circuitry protecting against damage due to high static voltage or electrical fields; however, normal precautions should be taken to avoid exceeding maximum voltage ratings. reliability is enhanced if unused inputs are tied to an appropriate logic voltage level (e.g., gnd, v ddd or v add ). table 2-1 maximum ratings spec. rating symbol value unit m 1 supply voltage v cc C0.3 to +3.3 v m 2 all input voltages v in gnd C0.5 to vcc +0.5 v m 3 current drain per pin excluding v dd and v ss i10ma m 4 operating temperature range t a C30 to +85 c m 5 storage temperature t stg C55 to +150 c
specifications recommended operating conditions preliminary 2-2 MC68176 technical data sheet motorola recommended operating conditions dc electrical characteristics table 2-2 recommended operating conditions spec. characteristic symbol min typ max unit 1 analog supply voltage (v add sel = 1) v add 1.8 2.0 2.2 v 2 analog supply voltage (v add sel = 0) v add 2.7 3.0 3.3 v 3 input clock frequency clock 38.4 khz 4 input clock duty cycle clock 45 50 55 % 5 operating temperature t a - 30 + 85 c table 2-3 dc electrical characteristics spec. characteristics symbol min typ max unit 6 output high voltage (i oh = C 0.3 ma, v ddd = 3.0 v 10%) v oh v ddd - 0.13 v 7 output high voltage (i oh = C 0.3 ma, v ddd = 2.0 v 10%) v oh v ddd - 0.3 v 8 output low voltage (i ol = 2 ma, v ddd = 3.0 v 10%) v ol 0.13 v 8 output low voltage (i ol = 2 ma, v ddd = 2.0 v 10%) v ol 0.3v 10 input high voltage v ih 0.8 v ddd v ddd v 11 input low voltage v il - 0.3 0.2 v ddd v 12 digital internal supply current (v ddd = 3 v) 10% iv ddd 2.58.0 m a 13 digital internal supply current (v ddd = 2 v 10%) iv ddd 1.65.3 m a 14 analog internal supply current (v add = 3 v 10%, v add sel = 0) i sby 110 220 m a 15 analog internal supply current (v add = 2v 10%, v add sel = 1) i sby 75 150 m a 16 standby supply current i sby 1 m a 17 digital input capacitance c di 10pf 18 analog input capacitance c ai 10pf 19 dc-offset range v dco 0.0 v add v
specifications peak and valley dac preliminary motorola MC68176 technical data sheet 2-3 peak and valley dac switch capacitor filter table 2-4 peak and valley dac spec. characteristic symbol min typ max unit 20 specification deleted 21 dac output voltage iv ag - 128 lsb iv ag + 128 lsb v 22 step size (input referred) lsb 0.3367 v add / 255 1% v 23 differential linearity 1 lsb 24 min/max full scale error 1 lsb 25 zero code error 7 lsb 26 voltage output drift, hold mode 0.0mv/ ms note: iv ag = (v add / 2) 1% table 2-5 switch capacitor filter spec. characteristic symbol min typ max unit 27 pass band gain (v add sel = 0) 11.16 11.26 11.36 db 28 pass band gain (v add sel = 1) 7.64 7.74 7.84 db 29 cutoff frequency, C 3 db, bw = 1 1.95 2.0 2.05 khz 30 cutoff frequency, C 3 db, bw = 0 0.95 1.0 1.05 khz 31 stabilization time, off mode to hold mode 5.0 ms 32 analog input impedance (f in = 10 khz) z in 1.0 m w 33 adin voltage range (see note) adin 0.0 v add v note: although the voltage on adin may be any value in the range specified, the actual maximum permitted ac signal peak is given by: v adin-peak = 0.410 v add / scfgain - v difoffset where v difoffset = |v adoffset - v dc-offset | (absolute value of error in signal dc-offset) v adoffset = actual dc offset of analog signal presented on adin v dc-offset = dc value present as signal dc-offset
specifications 2-bit a/d converter preliminary 2-4 MC68176 technical data sheet motorola 2-bit a/d converter table 2-6 2-bit a/d converter spec. characteristic min typ max unit 34 lower threshold valley + (peak - valley) 1/6; 0.00625 @ peak - valley = 125 mv v 35 middle threshold valley + (peak - valley) 1/2; 0.00625 @ peak - valley = 125 mv v 36 upper threshold valley + (peak - valley) 5/6; 0.00625 @ peak - valley = 125 mv v note: maximum ac peak input voltage on adin (v add sel = 1, scfgain = 2.437 1%) and (v add sel = 0, scfgain = 3.656 1%): v adin-peak = (0.410 v add / scfgain - v diffoffset ) v diffoffset = | v adoffset - v dc-offset | v adoffset = dc value of the analog signal adin v dc-offset = voltage of input offset signal dc-offset. (v diffoffset is the absolute value of the difference between v adoffset and v dc-offset, that is the absolute value of the error in the input offset signal dc-offset.)
specifications timing diagrams preliminary motorola MC68176 technical data sheet 2-5 timing diagrams figure 2-1 external timings figure 2-2 internal timings clock trkinh (external) trkinh (internal) peak/valley counter counts value a value b based on value a based on value b exts1, exts0 outputs aa1292 clock (external) clock (internal analog) clock (internal digital) peak sampled & held scf input sampled logital inputs sampled exts1 / exts0 output scf output sampled 2-bit a/d sample valley sampled aa1293
specifications timing diagrams preliminary 2-6 MC68176 technical data sheet motorola
preliminary motorola MC68176 technical data sheet 3-1 section 3 packaging pin-out and package information this sections provides information about the available packages for this product, including diagrams of the package pinouts and tables describing how the signals described in section 1 are allocated. the MC68176 is available in a 14-pin small outline integrated circuit (soic) package.
packaging pin-out and package information preliminary 3-2 MC68176 technical data sheet motorola tqfp package description top and bottom views of the soic package are shown in figure 3-1 and figure 3-2 with their pinouts. figure 3-1 MC68176 small outline integrated circuit (soic), top view figure 3-2 MC68176 small outline integrated circuit (soic), bottom view v ddd v add adin dc-offset v add sel gnd bw clock reserved trkinh exts0 exts1 con2 con1 1 78 14 aa1294 v ddd v add adin dc-offset v add sel gnd bw clock reserved trkinh exts0 exts1 con2 con1 1 7 8 14 aa1295
packaging pin-out and package information preliminary motorola MC68176 technical data sheet 3-3 table 3-1 signal by pin number pin # signal name pin # signal name 1v ddd 8con1 2v add 9con2 3adin10exts1 4 dc-offset 11 exts0 5v add sel 12 trkinh 6v ss 13 reserved 7 bw 14 clock table 3-2 signal by name signal name pin # signal name pin # adin 3 exts1 10 bw 7 reserved 13 clock 14 trkinh 12 con1 8 v add 2 con2 9 v add sel 5 dc-offset 4 v ddd 1 exts0 11 v ss 6 figure 3-3 14-pin small outline integrated circuit (soic) mechanical information notes: 1. dimensioning and tolerancing per ansi y14.5m, 1982. 2. controlling dimension: millimeter. 3. dimensions a and b do not include mold protrusion. 4. maximum mold protrusion 0.15 per side. 5. dimension d does not include dambar protrusion. allowable dambar protrusion shall be 0.127 total in excess of the d dimension at maximum material condition. a b g p 7 pl 14 8 7 1 m 0.25 b m s b m 0.25 a s t t f r x 45 seating plane d 14 pl k c j m dim min max millimeters a 8.55 8.75 b 3.80 4.00 c 1.35 1.75 d 0.35 0.49 f 0.40 1.25 g 1.27 bsc j 0.19 0.25 k 0.10 0.25 m 0 7 p 5.80 6.20 r 0.25 0.50
packaging ordering drawings preliminary 3-4 MC68176 technical data sheet motorola ordering drawings complete mechanical information regarding MC68176 packaging is available by facsimile through motorola's mfax? system. call the following number to obtain information by facsimile: the mfax automated system requests the following information: ? the receiving facsimile telephone number including area code or country code ? the callers personal identification number (pin) note: for first time callers, the system provides instructions for setting up a pin, which requires entry of a name and telephone number. ? the type of information requested: C instructions for using the system C a literature order form C specific part technical information or data sheets C other information described by the system messages a total of three documents may be ordered per call. the MC68176 14-pin soic package mechanical drawing is referenced as 751-a. (602) 244-6609
preliminary motorola MC68176 technical data sheet 4-1 section 4 design considerations thermal design considerations an estimation of the chip junction temperature, t j , in c can be obtained from the equation: equation 1: where: t a = ambient temperature c r q ja = package junction-to-ambient thermal resistance c/w p d = power dissipation in package historically, thermal resistance has been expressed as the sum of a junction-to-case thermal resistance and a case-to-ambient thermal resistance: equation 2: where: r q ja = package junction-to-ambient thermal resistance c/w r q jc = package junction-to-case thermal resistance c/w r q ca = package case-to-ambient thermal resistance c/w r q jc is device-related and cannot be influenced by the user. the user controls the thermal environment to change the case-to-ambient thermal resistance, r q ca . for example, the user can change the air flow around the device, add a heat sink, change the mounting arrangement on the printed circuit board (pcb), or otherwise change the thermal dissipation capability of the area surrounding the device on a pcb. this model is most useful for ceramic packages with heat sinks; some 90% of the heat flow is dissipated through the case to the heat sink and out to the ambient environment. for ceramic packages, in situations where the heat flow is split between a path to the case and an alternate path through the pcb, analysis of the device thermal performance may need the additional modeling capability of a system level thermal simulation tool. t j t a p d r q ja () + = r q ja r q jc r q ca + =
design considerations thermal design considerations preliminary 4-2 MC68176 technical data sheet motorola the thermal performance of plastic packages is more dependent on the temperature of the pcb to which the package is mounted. again, if the estimations obtained from r q ja do not satisfactorily answer whether the thermal performance is adequate, a system level model may be appropriate. a complicating factor is the existence of three common ways for determining the junction-to-case thermal resistance in plastic packages: ? to minimize temperature variation across the surface, the thermal resistance is measured from the junction to the outside surface of the package (case) closest to the chip mounting area when that surface has a proper heat sink. ? to define a value approximately equal to a junction-to-board thermal resistance, the thermal resistance is measured from the junction to where the leads are attached to the case. ? if the temperature of the package case (t t ) is determined by a thermocouple, the thermal resistance is computed using the value obtained by the equation (t j - t t ) / p d . as noted above, the junction-to-case thermal resistances quoted in this data sheet are determined using the first definition. from a practical standpoint, that value is also suitable for determining the junction temperature from a case thermocouple reading in forced convection environments. in natural convection, using the junction-to-case thermal resistance to estimate junction temperature from a thermocouple reading on the case of the package will estimate a junction temperature slightly hotter than actual temperature. hence, the new thermal metric, thermal characterization parameter or y jt , has been defined to be (t j - t t ) / p d . this value gives a better estimate of the junction temperature in natural convection when using the surface temperature of the package. remember that surface temperature readings of packages are subject to significant errors caused by inadequate attachment of the sensor to the surface and to errors caused by heat loss to the sensor. the recommended technique is to attach a 40- gauge thermocouple wire and bead to the top center of the package with thermally conductive epoxy.
design considerations application design considerations preliminary motorola MC68176 technical data sheet 4-3 application design considerations the flex chip ic connects to a receiver capable of converting a four-level audio signal into a 2-bit digital signal with the MC68176 flex 2-bit d/a. the flex chip ic has eight receiver control lines used for warming up and shutting down a receiver in stages, dual bandwidth control signals for two post detection filter bandwidths for receiving the two symbol rates of the flex signal, and the ability to detect a low battery signal during the receiver control sequences. it interfaces to a host mcu through a standard spi. it has a 38.4 khz clock output capable of driving other devices, in particular the MC68176. it has a 1 minute timer that offers low power support for time of day function on the host. figure 4-1 shows a typical application block diagram. figure 4-1 flex chip system block diagram spi mc68175 flex chip ic decoder audio 38.4 khz clock out rf mc13141 mc13142 mmbr941 mc13150 mc3367 mc3374 mc68hc05xxhc08xx mc68hc11/hc12/hc16xx mc683xx/mpc5xx/8xx api flexstack? software data ready receiver control 76.8 khz oscillator analog to digital converter user interface lna if host microprocessor aa0814 MC68176 2-bit a/d converter dsp568xx
design considerations application design considerations preliminary 4-4 MC68176 technical data sheet motorola sample application circuit figure 4-2 shows an application example of the MC68176 2-bit flex a/d chip in a flex pager application. the MC68176 a/d chip will convert an analog flex base- band signal into a 2-bit digital signal. the MC68176 a/d can be controlled by a flex decoder, such as the mc68175 or mc68181. the following schematic shows the MC68176 a/d chip in a pager application. note that the dc offset of the audio input signal to the flex a/d must be applied to the dc-offset pin for the converter to work properly. theoretically speaking, we can view the dc-offset pin as an internal resistance of 50 k w and a internal capacitance of 1.6 pf in serial. so, the external resisters, r1, r2, and r3 can be as large as 600 k w , 600 k w , and 60 k w, respectively this will guarantee settling to an accuracy of at least 9 bits. figure 4-2 an application example for the MC68176, flex a/d 10 k w 10 k w 1 k w if/demodulator nrf3034a audio 18 k w 0.0018 v add dc- v ddd v add sel adin reserved gnd exts0 exts1 trkinh con2 con1 bw clock flex a/d MC68176 exts0 exts1 symclk s6 s5 s4 clkout ready miso sck mosi ss reset flex chip decoder mc68175 irq miso sck mosi ss gpio dsp56l811 r1 r3 r4 host microprocessor 0.1 m f 1.0 v add 0.1 m f 1.0 v add m f offset r2 aa1296 m f m f 0.1 m f
preliminary motorola MC68176 technical data sheet 5-1 section 5 ordering information consult a motorola semiconductor sales office or authorized distributor to determine product availability and to place an order. table 5-1 ordering information part supply voltage package type pin count frequency (khz) order number MC68176 1.8 v3.3 v (see note 1) soic 14 38.4 MC68176dw note: 1. the MC68176 has two separate power rails for the analog and digital portions of the circuitry, v add and v ddd . both rails may be set independently to a nominal 2.0 v or 3.0 v supply.
ordering information preliminary 5-2 MC68176 technical data sheet motorola
preliminary motorola MC68176 technical data sheet a-1 appendix a description of operation operational description the MC68176 is a four-level audio band 2-bit a/d symbol decoder for the flex paging system. the input signal to the adin pin is generated by a flex rf receiver. there are four amplitude levels, which represent four unique output digital codes. the digital levels are defined relative to the peak and valley voltages of the signal. the ideal digital transition levels are at the following thresholds: ? upper threshold = (peak - valley) 5 / 6 + valley ? middle threshold = (peak - valley) 1 / 2 + valley ? lower threshold = (peak - valley) 1 / 6 + valley the gray scale regions are shown in table a-1 on page a-2. figure a-1 adin analog input signal peak valley 5/6 1/2 1/6 aa1297
description of operation operational description preliminary a-2 MC68176 technical data sheet motorola each threshold in table a-1 must be accurate to within 5% of the ideal threshold, or the flex bit error rate will increase beyond acceptable levels. the problem is that both the amplitude and the dc offset of the received signal will be affected by many variablestemperature, voltage, production lot, vendor, and receiver design. because of this increase in the dynamic range, an 8-bit dac is required for both the peak and valley servo loops. this means that the peak and valley levels used by the MC68176 are within one lsb of the actual peak and valley voltage levels. peak and valley servo description a control loop is used to acquire the actual peak and valley voltages to an accuracy of one lsb. the peak control loop is described below; the valley control loop is similar, with appropriate changes made to acquire a minimum rather than a maximum signal value. the flex system uses a symbol rate of 1600 symbols per second during the synchronization period. the MC68176 must acquire the peak and valley levels in six symbol periods, with sufficient accuracy that the threshold levels used by the two-bit a/d are within 5% of the actual thresholds. table a-1 gray scale regions signal range exts1, exts0 peak 1, 0 5/6 1, 1 1/2 0, 1 1/6 0, 0 valley figure a-2 peak/valley control loop 8-bit dac ctr v in v peak aa1298
description of operation operational description preliminary motorola MC68176 technical data sheet a-3 there are two tracking modes, fast track mode and slow track mode. the use of these two modes allows the threshold specification to be acquired in the required six symbol periods, that is 6/1600 seconds or six times 625 m s. fast track mode is used for one symbol period to obtain a very approximate value quickly, and slow track mode is used for the remaining five periods to obtain an accurate value. in both fast track mode and slow track mode, the control loop acquires the peak and valley by attacking or decaying the peak counter at different rates. in fast track mode, tracking is controlled only by the relative levels of the two signals v in and the peak dac output. if the peak dac output is above v in , then the peak counter will decay, and if it is below v in , then the peak counter will attack. slow track mode is a little more complicated. for the peak counter to decay, trkinh must be low (i.e., tracking is not inhibited), the peak dac output must be greater than v in , and no attack or decay may have happened for a set number of clock cycles. if all these conditions are met, then the peak dac is decremented. the peak counter is incremented if trkinh is low and the peak dac output is less than v in .
description of operation operational description preliminary a-4 MC68176 technical data sheet motorola
motorola reserves the right to make changes without further notice to any products herein. motorola makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does motorola assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation consequential or incidental damages. typical parameters which may be provided in motorola data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. all operating parameters, including typicals must be validated for each customer application by customers technical experts. motorola does not convey any license under its patent rights nor the rights of others. motorola products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support life, or for any other application in which the failure of the motorola product could create a situation where personal injury or death may occur. should buyer purchase or use motorola products for any such unintended or unauthorized application, buyer shall indemnify and hold motorola and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that motorola was negligent regarding the design or manufacture of the part. motorola and are registered trademarks of motorola, inc. motorola, inc. is an equal opportunity/ affirmative action employer. how to reach us: usa/europe/locations not listed : motorola literature distribution p.o. box 5405 denver, colorado 80217 1 (800) 441-2447 1 (303) 675-2140 mfax? : rmfax0@email.sps.mot.com touchtone (602) 244-6609 usa and canada only: 1 (800) 774-1848 asia/pacific : motorola semiconductors h.k. ltd. 8b tai ping industrial park 51 ting kok road tai po, n.t., hong kong 852-26629298 technical resource center: 1 (800) 521-6274 dsp helpline dsphelp@dsp.sps.mot.com japan : nippon motorola ltd spd, strategic planning office 4-32-1, nishi- gotanda shinagawa-ku, tokyo 141, japan 81-3-5487-8488 internet : http://www.motorola.com/sps mfax, flex and flexstack are trademarks of motorola inc.

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