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PRELIMINARY
CY7C9925
3.3V/2.5V Programmable Skew Clock Buffer
Features
* All output pair skew <100 ps (typical) * Input Frequency Range: 3.75 MHz to 200 MHz * Output Frequency Range: 3.75 MHz to 200 MHz * User-selectable output functions -- Selectable skew to 18 ns -- Inverted and non-inverted -- Operation at 12 and 14 input frequency -- Operation at 2x and 4x input frequency (input as low as 3.75 MHz) * Zero input-to-output delay * 3.3V Core power supply * Split 2.5V or 3.3V Output power supplies * 2.5% Output Duty Cycle Distortion for 3.3V Output * LVTTL outputs drive 50 terminated lines * Low operating current * 32-pin QFN package * Jitter < 100ps peak-to-peak (< 15 ps RMS)
Functional Description
The CY7C9925 RoboClock is 200-MHz Low-voltage Programmable Skew Clock Buffer that offers user-selectable control over system clock functions. This multiple-output clock driver provides the system integrator with functions necessary to optimize the timing of high-performance computer systems. Eight individual drivers, arranged as four pairs of user-controllable outputs, can each drive terminated transmission lines with impedances as low as 50 while delivering minimal and specified output skews and full-swing logic levels (LVTTL). Each output can be hardwired to one of nine delay or function configurations. Delay increments of 0.32 to 1.6 ns are determined by the operating frequency with outputs able to skew up to 6 time units from their nominal "zero" skew position. The completely integrated PLL allows external load and transmission line delay effects to be canceled. When this "zero delay" capability of the LVPSCB is combined with the selectable output skew functions, the user can create output-to-output delays of up to 12 time units. Divide-by-two and divide-by-four output functions are provided for additional flexibility in designing complex clock systems. When combined with the internal PLL, these divide functions allow distribution of a low-frequency clock that can be multiplied by two or four at the clock destination. This facility minimizes clock distribution difficulty while allowing maximum system clock speed and flexibility.
Block Diagram
TEST PHASE FREQ DET FS 4F0 4F1 4Q0 SELECT INPUTS (THREE LEVEL) 4Q1 SKEW 3Q0 3Q1 2Q0 MATRIX 2Q1 1Q0 1Q1
Pin Configuration
VCCQ TEST GND REF 3F0 2F1 FS 2F0
FB REF
FILTER
VCO AND TIME UNIT GENERATOR
3F1 4F0 4F1 VCCQ VCCN4 4Q1 4Q0 GND
SELECT
1 2 3 4 5 6 7 8
32 31 30 29 28 27 26 25 24 23 22 21
GND 1F1 1F0 VCCN1 1Q0 1Q1 GND GND
CY7C9925
20 19 18 17
3F0 3F1
9
10 11 12 13 14 15 16
VCCN3
VCCN2
2F0 2F1
GND
3Q1
3Q0
FB
2Q1
1F0 1F1
Cypress Semiconductor Corporation Document #: 38-07688 Rev. **
*
3901 North First Street
*
San Jose, CA 95134 * 408-943-2600 Revised June 25, 2004
2Q0
PRELIMINARY
Pin Definitions
Pin No. 29 13 31 22,23 25,26 32,1 2, 3 27 19,20 15,16 10,11 6,7 21 14 12 5 4,30 Name Ref FB FS 1F0, 1F1 2F0, 2F1 3F0, 3F1 4F0, 4F1 Test I/O Input Input Input Input Input Input Input Input LVTTL Three-level Three-level Three-level Three-level Three-level Three-level LVTTL LVTTL LVTTL LVTTL POWER POWER POWER POWER POWER POWER Type LVTTL/LVCMOS Reference Clock Input Feedback Clock Input Three Level Frequency Range Select Three level function select for 1Q0,1Q1 Three level function select for 2Q0,2Q1 Three level function select for 3Q0,3Q1 Three level function select for 4Q0,4Q1 Three level select for test modes Output Pair Output Pair Output Pair Output Pair Description
CY7C9925
1Q0, 1Q1 Output 2Q0, 2Q1 Output 3Q0, 3Q1 Output 4Q0, 4Q1 Output VCCN1 VCCN2 VCCN3 VCCN4 VCCQ Power Power Power Power Power Ground
3.3V or 2.5V Power Supply for output pair 1Q0 and 1Q1. 3.3V or 2.5V Power Supply for output pair 2Q0 and 2Q1. 3.3V or 2.5V Power Supply for output pair 3Q0 and 3Q1. 3.3V or 2.5V Power Supply for output pair 4Q0 and 4Q1. 3.3V Core Power Ground Table 1. Frequency Range Select and tU Calculation[1] fNOM (MHz) FS[2] LOW MID HIGH Min. 15 25 40 Max. 30 50 200
1 t U = ----------------------f NOM x N
8,9,17,18,24,28 GND
Block Diagram Description
Phase Frequency Detector and Filter These two blocks accept inputs from the Reference Frequency (REF) input and the Feedback (FB) input and generate correction information to control the frequency of the Voltage-Controlled Oscillator (VCO). These blocks, along with the VCO, form a Phase-Locked Loop (PLL) that tracks the incoming REF signal. VCO and Time Unit Generator The VCO accepts analog control inputs from the PLL filter block and generates a frequency that is used by the time unit generator to create discrete time units that are selected in the skew select matrix. The operational range of the VCO is determined by the FS control pin. The time unit (tU) is determined by the operating frequency of the device and the level of the FS pin as shown in Table 1.
where N = 44 26 16
Approximate Frequency (MHz) At Which tU = 1.0 ns 22.7 38.5 62.5
Skew Select Matrix The skew select matrix is comprised of four independent sections. Each section has two low-skew, high-fanout drivers (xQ0, xQ1), and two corresponding three-level function select (xF0, xF1) inputs. Table 2 below shows the nine possible output functions for each section as determined by the function select inputs. All times are measured with respect to the REF input assuming that the output connected to the FB input has 0tU selected.
Notes: 1. For all three-state inputs, HIGH indicates a connection to VCC, LOW indicates a connection to GND, and MID indicates an open connection. Internal termination circuitry holds an unconnected input to VCC/2. 2. The level to be set on FS is determined by the "normal" operating frequency (fNOM) of the VCO and Time Unit Generator (see Logic Block Diagram). Nominal frequency (fNOM) always appears at 1Q0 and the other outputs when they are operated in their undivided modes (see Table 2). The frequency appearing at the REF and FB inputs will be fNOM when the output connected to FB is undivided. The frequency of the REF and FB inputs will be fNOM/2 or fNOM/4 when the part is configured for a frequency multiplication by using a divided output as the FB input.
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PRELIMINARY
Table 2. Programmable Skew Configurations[1] Function Selects Output Functions 3Q0, 3Q1 -6tU -4tU -2tU 0tU +2tU +4tU +6tU Divide by 4
t 0 - 6t U t 0 - 5t U t 0 - 4t U
CY7C9925
1F1, 2F1, 1F0, 2F0, 1Q0, 1Q1, 3F1, 4F1 3F0, 4F0 2Q0, 2Q1 LOW LOW LOW MID MID MID HIGH HIGH HIGH LOW MID HIGH LOW MID HIGH LOW MID HIGH -4tU -3tU -2tU -1tU 0tU +1tU +2tU +3tU +4tU
4Q0, 4Q1 -6tU -4tU -2tU 0tU +2tU +4tU +6tU Inverted
t 0 - 3t U t 0 - 2t U t 0 - 1t U
U U U U U U
Divide by 2 Divide by 2
t 0 +1t
t 0 +2t
t 0 +3t
t 0 +4t
t 0 +5t
FBInput REFInput 1Fx 2Fx (N/A) LL LM LH ML MM MH HL HM HH (N/A) (N/A) (N/A) 3Fx 4Fx LM LH (N/A) ML (N/A) MM (N/A) MH (N/A) HL HM LL/HH HH - 6tU - 4tU - 3tU - 2tU - 1tU 0tU +1tU +2tU +3tU +4tU +6tU DIVIDED INVERT
Figure 1. Typical Outputs with FB Connected to a Zero-Skew Output[3]
Note: 3. FB connected to an output selected for "zero" skew (i.e., xF1 = xF0 = MID).
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t 0 +6t
t0
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PRELIMINARY
Test Mode
The TEST input is a three-level input. In normal system operation, this pin is connected to ground, allowing the CY7C9925 to operate as explained briefly above (for testing purposes, any of the three-level inputs can have a removable jumper to ground, or be tied LOW through a 100 resistor. This will allow an external tester to change the state of these pins.)If the TEST input is forced to its MID or HIGH state, the
CY7C9925
device will operate with its internal phase locked loop disconnected, and input levels supplied to REF will directly control all outputs. Relative output to output functions are the same as in normal mode. In contrast with normal operation (TEST tied LOW). All outputs will function based only on the connection of their own function select inputs (xF0 and xF1) and the waveform characteristics of the REF input.
Operational Mode Descriptions
REF L1 Z0 LOAD
SYSTEM CLOCK
FB REF FS 4F0 4F1 3F0 3F1 2F0 2F1 1F0 1F1 TEST LENGTH L1 = L2 = L3 = L4 4Q0 4Q1 3Q0 3Q1 2Q0 2Q1 1Q0 1Q1
LOAD L2 Z0 LOAD L3 Z0 L4 Z0 LOAD
Figure 2. Zero-Skew and/or Zero-Delay Clock Driver Figure 2 shows the LVPSCB configured as a zero-skew clock buffer. In this mode the CY7C9925 can be used as the basis for a low-skew clock distribution tree. When all of the function select inputs (xF0, xF1) are left open, the outputs are aligned and may each drive a terminated transmission line to an independent load. The FB input can be tied to any output in
REF Z0
this configuration and the operating frequency range is selected with the FS pin. The low-skew specification, coupled with the ability to drive terminated transmission lines (with impedances as low as 50), allows efficient printed circuit board design.
LOAD L1
SYSTEM CLOCK
FB REF FS 4F0 4F1 3F0 3F1 2F0 2F1 1F0 1F1 TEST
4Q0 4Q1 3Q0 3Q1 2Q0 2Q1 1Q0 1Q1 LENGTH L1 = L2 L3 < L2 by 6 inches L4 > L2 by 6 inches
LOAD L2 Z0 LOAD Z0 L4 Z0 LOAD
L3
Figure 3. Programmable-Skew Clock Driver Figure 3 shows a configuration to equalize skew between metal traces of different lengths. In addition to low skew between outputs, the LVPSCB can be programmed to stagger the timing of its outputs. The four groups of output pairs can Document #: 38-07688 Rev. ** each be programmed to different output timing. Skew timing can be adjusted over a wide range in small increments with the appropriate strapping of the function select pins. In this configuration the 4Q0 output is fed back to FB and configured for Page 4 of 12
PRELIMINARY
zero skew. The other three pairs of outputs are programmed to yield different skews relative to the feedback. By advancing the clock signal on the longer traces or retarding the clock signal on shorter traces, all loads can receive the clock pulse at the same time. In this illustration the FB input is connected to an output with 0-ns skew (xF1, xF0 = MID) selected. The internal PLL synchronizes the FB and REF inputs and aligns their rising edges to insure that all outputs have precise phase alignment. Clock skews can be advanced by 6 time units (tU) when using an output selected for zero skew as the feedback. A wider range of delays is possible if the output connected to FB is also skewed. Since "Zero Skew", +tU, and -tU are defined relative to output groups, and since the PLL aligns the rising edges of REF and FB, it is possible to create wider output skews by proper selection of the xFn inputs. For example a +10 tU between REF and 3Qx can be achieved by connecting 1Q0 to FB and setting 1F0 = 1F1 = GND, 3F0 = MID, and 3F1 = High. (Since FB aligns at -4 tU and 3Qx skews to +6 tU, a total of +10 tU skew is realized.) Many other configurations can be realized by skewing both the output used as the FB input and skewing the other outputs.
REF 20 MHz FB REF FS 4F0 4F1 3F0 3F1 2F0 2F1 1F0 1F1 TEST
CY7C9925
REF
4Q0 4Q1 3Q0 3Q1 2Q0 2Q1 1Q0 1Q1
40 MHz 20 MHz 80 MHz
Figure 5. Frequency Multiplier with Skew Connections Figure 5 illustrates the LVPSCB configured as a clock multiplier. The 3Q0 output is programmed to divide by four and is fed back to FB. This causes the PLL to increase its frequency until the 3Q0 and 3Q1 outputs are locked at 20 MHz while the 1Qx and 2Qx outputs run at 80 MHz. The 4Q0 and 4Q1 outputs are programmed to divide by two, which results in a 40-MHz waveform at these outputs. Note that the 20- and 40-MHz clocks fall simultaneously and are out of phase on their rising edge. This will allow the designer to use the rising edges of the 12 frequency and 14 frequency outputs without concern for rising-edge skew. The 2Q0, 2Q1, 1Q0, and 1Q1 outputs run at 80 MHz and are skewed by programming their select inputs accordingly. Note that the FS pin is wired for 80-MHz operation because that is the frequency of the fastest output.
REF
FB REF FS 4F0 4F1 3F0 3F1 2F0 2F1 1F0 1F1 TEST 4Q0 4Q1 3Q0 3Q1 2Q0 2Q1 1Q0 1Q1
20 MHz
Figure 4. Inverted Output Connections Figure 4 shows an example of the invert function of the LVPSCB. In this example the 4Q0 output used as the FB input is programmed for invert (4F0 = 4F1 = HIGH) while the other three pairs of outputs are programmed for zero skew. When 4F0 and 4F1 are tied HIGH, 4Q0 and 4Q1 become inverted zero phase outputs. The PLL aligns the rising edge of the FB input with the rising edge of the REF. This causes the 1Q, 2Q, and 3Q outputs to become the "inverted" outputs with respect to the REF input. By selecting which output is connect to FB, it is possible to have 2 inverted and 6 non-inverted outputs or 6 inverted and 2 non-inverted outputs. The correct configuration would be determined by the need for more (or fewer) inverted outputs. 1Q, 2Q, and 3Q outputs can also be skewed to compensate for varying trace delays independent of inversion on 4Q.
FB REF FS 4F0 4F1 3F0 3F1 2F0 2F1 1F0 1F1 TEST 4Q0 4Q1 3Q0 3Q1 2Q0 2Q1 1Q0 1Q1
10 MHz 5 MHz 20 MHz
Figure 6. Frequency Divider Connections Figure 6 demonstrates the LVPSCB in a clock divider application. 2Q0 is fed back to the FB input and programmed for zero skew. 3Qx is programmed to divide by four. 4Qx is programmed to divide by two. Note that the falling edges of the 4Qx and 3Qx outputs are aligned. This allows use of the rising edges of the 12 frequency and 14 frequency without concern for skew mismatch. The 1Qx outputs are programmed to zero skew and are aligned with the 2Qx outputs. In this example, the FS input is grounded to configure the device in the 15- to
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PRELIMINARY
30-MHz range since the highest frequency output is running at 20 MHz. Figure 7 shows some of the functions that are selectable on the 3Qx and 4Qx outputs. These include inverted outputs and outputs that offer divide-by-2 and divide-by-4 timing. An inverted output allows the system designer to clock different subsystems on opposite edges, without suffering from the pulse asymmetry typical of non-ideal loading. This function allows the two subsystems to each be clocked 180 degrees out of phase, but still to be aligned within the skew spec. The divided outputs offer a zero-delay divider for portions of the system that need the clock to be divided by either two or four, and still remain within a narrow skew of the "1X" clock.
CY7C9925
Without this feature, an external divider would need to be added, and the propagation delay of the divider would add to the skew between the different clock signals. These divided outputs, coupled with the Phase Locked Loop, allow the LVPSCB to multiply the clock rate at the REF input by either two or four. This mode will enable the designer to distribute a low-frequency clock between various portions of the system, and then locally multiply the clock rate to a more suitable frequency, while still maintaining the low-skew characteristics of the clock driver. The LVPSCB can perform all of the functions described above at the same time. It can multiply by two and four or divide by two (and four) at the same time that it is shifting its outputs over a wide range or maintaining zero skew between selected outputs.
REF Z0 27.5-MHz DISTRIBUTION CLOCK FB REF FS 4F0 4F1 3F0 3F1 2F0 2F1 1F0 1F1 TEST 4Q0 4Q1 3Q0 3Q1 2Q0 2Q1 1Q0 1Q1 110-MHz INVERTED
LOAD
LOAD 27.5-MHz Z0 LOAD 110-MHz ZERO SKEW 110-MHz SKEWED -2.273 ns (-4tU) Z0 LOAD Z0
Figure 7. Multi-Function Clock Driver
REF Z0 L1 FB SYSTEM CLOCK REF FS 4F0 4F1 3F0 3F1 2F0 2F1 1F0 1F1 TEST Z0 L2 Z0
LOAD
LOAD 4Q0 4Q1 3Q0 3Q1 2Q0 2Q1 1Q0 1Q1 L4
FB REF FS 4F0 4F1 3F0 3F1 2F0 2F1 1F0 1F1 TEST
L3 Z0
LOAD
4Q0 4Q1 3Q0 3Q1 2Q0 2Q1 1Q0 1Q1
LOAD
LOAD
Figure 8. Board-to-Board Clock Distribution Figure 8 shows the CY7C9925 connected in series to construct a zero-skew clock distribution tree between boards. Delays of the downstream clock buffers can be programmed to compensate for the wire length (i.e., select negative skew equal to the wire delay) necessary to connect them to the master clock source, approximating a zero-delay clock tree. Cascaded clock buffers will accumulate low-frequency jitter because of the non-ideal filtering characteristics of the PLL filter. It is recommended that not more than two clock buffers be connected in series.
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PRELIMINARY
Absolute Maximum Conditions
Parameter VDD VIN VIN LUI TS TA TA TJ OJc OJa ESDh MSL GATES UL-94 FIT TPU CIN ZOUT Description Supply Voltage Input Voltage REF Input Voltage Except REF Latch-up Immunity Temperature, Storage Temperature, Operating Ambient Temperature, Operating Ambient Junction Temperature Dissipation, Junction to Case Dissipation, Junction to Ambient ESD Protection (Human Body Model) Moisture Sensitivity Level Total Functional Gate Count Flammability Rating Failure in Time Power-up time for all VDDs to reach minimum specified voltage (power ramps must be monotonic) Input Capacitance[4] Output Impedance TA = 25C, f = 1 MHz, VCC = 3.3V Low to High (Rising edge) High to Low (Falling edge) Range [5] Test Conditions @3.3V 10% @3.3V 10% @2.5V 5% VOH VOL VIH VIL VIHH VIMM VILL IIH Output HIGH Voltage Output LOW Voltage Input HIGH Voltage (REF and FB inputs only)[6] Input LOW Voltage (REF and FB inputs only)[6] Three-Level Input HIGH Voltage (Test, FS, xFn)[7] Three-Level Input MID Voltage (Test, FS, xFn)[7] Three-Level Input LOW Voltage (Test, FS, xFn)[7] Input HIGH Leakage Current (REF and FB inputs only) Min. VCC Max. Min. VCC Max. Min. VCC Max. VCC = Max., VIN = Max. VCC = Min., IOH = -20 mA (3.3V) VCC = Min., IOH = -15 mA (2.5V) VCC = Min., IOL = 36 mA (3.3V) VCC = Min., IOL = 20 mA (2.5V) Min. 2.97 2.97 2.375 2.4 1.8 - - 2.0 -0.5 0.87 * VCC 0.47 * VCC 0.0 - Assembled Die @ 1/8 in. Manufacturing test 0.05 Condition Nonfunctional Relative to VCC Relative to VCC Functional Nonfunctional Commercial Temperature Industrial Temperature Industrial Temperature Functional Functional TBD TBD 2000 MSL - 1 TBD V-0 10 -65 0 -40 Min. -0.5 -0.5 -0.5 300
CY7C9925
Max. 4.6 4.6 VDD + 0.5 +125 +70 +85 125 Unit VDC VDC VDC mA C C C C C/W C/W V Class Each class ppm 500 ms
- 27 7
10
pF
Electrical Characteristics Over the Operating
Parameter VCCQ VCCN[1:4] Description Core Power Supply Output Buffer Power Supply
Max. 3.63 3.63 2.625 - - 0.45 0.4 VCC 0.8 VCC 0.53 * VCC 0.13 * VCC 10 V V V V V A V V V V V
Notes: 4. Applies to REF and FB inputs only. Tested initially and after any design or process changes that may affect these parameters. 5. See the last page of this specification for Group A subgroup testing information. 6. VIH and VIL for FB inputs guaranteed by statistical correlation. Tested initially and after any design or process changes that may affect this parameters.
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PRELIMINARY
Electrical Characteristics Over the Operating Range (continued)[5]
Parameter IIL IIHH IIMM IILL IOS ICCQ ICCN PD Description Input LOW Leakage Current (REF and FB inputs only) Input HIGH Current (Test, FS, xFn) Input MID Current (Test, FS, xFn) Input LOW Current (Test, FS, xFn) Short Circuit Current[8] Operating Current Used by Internal Circuitry Output Buffer Current per Output Pair[9] Power Dissipation per Output Pair[10] Test Conditions VCC = Max., VIN = 0.4V VIN = VCC VIN = VCC/2 VIN = GND VCC = MAX, VOUT = GND (25 only) VCCN = VCCQ = Max., All Input Selects Open VCCN = VCCQ = Max., IOUT = 0 mA Input Selects Open, fMAX VCCN = VCCQ = Max., IOUT = 0 mA Input Selects Open, fMAX Min. -10 - -50 - - - - - -
CY7C9925
Max. - 200 50 -200 -200 90 100 14 78 mA mW A A A A mA mA
AC Test Loads and Waveforms
VCC R1 CL R1=100 R2=100 CL = 30 pF (Includes fixture and probe capacitance) 2.0V Vth =1.5V 0.8V 0.0V 1ns 3.0V 2.0V Vth =1.5V 0.8V 1ns
R2
TTL AC Test Load
TTL Input Test Waveform
AC Input Specifications
Parameter TR,TF TPWC TDCIN FREF Description Input Rise/Fall Edge Rate Input Clock Pulse Input Duty Cycle Reference Input Frequency 0.8V - 2.0V HIGH or LOW PLL Test Mode FS=LOW FS=MID FS=HIGH Condition Min. - 2 10 30 3.75 6.25 10 Max. 10 - 90 70 30 50 200[11] MHz Unit ns/V ns %
Notes: 7. These inputs are normally wired to VCC, GND, or left unconnected (actual threshold voltages vary as a percentage of VCC). Internal termination resistors hold unconnected inputs at VCC/2. If these inputs are switched, the function and timing of the outputs may glitch and the PLL may require an additional tLOCK time before all data sheet limits are achieved. 8. CY7C9925 should be tested one output at a time, output shorted for less than one second, less than 10% duty cycle. Room temperature only. 9. Total output current per output pair can be approximated by the following expression that includes device current plus load current: CY7C9925:ICCN = [(4 + 0.11F) + [[((835 -3F)/Z) + (.0022FC)]N] x 1.1 Where F = frequency in MHz C = capacitive load in pF Z = line impedance in ohms N = number of loaded outputs; 0, 1, or 2 FC = F C 10. Total power dissipation per output pair can be approximated by the following expression that includes device power dissipation plus power dissipation due to the load circuit: PD = [(22 + 0.61F) + [[(1550 + 2.7F)/Z) + (.0125FC)]N] x 1.1 See note 9 for variable definition. 11. In test mode, Max REF input frequency is 133MHz.
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PRELIMINARY
Switching Characteristics Over the Operating Range [2, 12]
Parameter fNOM Operating Clock Frequency in MHz Output Frequency Description FS = LOW[1, 2] FS = MID[1, 2] FS = HIGH[1, 2 ] FS=LOW FS=MID FS=HIGH Min. 15 25 40 3.75 6.25 10 160 - - - - - - - - -0.15 47.5 45 47.5 45 47.5 45 0.15 0.15 - - - - - -
CY7C9925
Typ. Max. - 30 - 50 - 200 - 30 - 50 - 200 - 800 1 - See Table 1 0.05 0.1 0.1 0.2 0.25 0.3 0.3 0.5 0.25 0.5 0.5 0.9 - 0.75 - +0.15 50 52.5 50 55 50 52.5 50 55 50 52.5 50 55 1.0 1.5 1.0 1.5 - 0.5 - 15 - 100 - 25 - 150 - 100 Unit MHz
FOUT
MHz
FVCO FBW tU tSKEWPR tSKEW0 tSKEW1 tSKEW2 tSKEW3 tSKEW4 tDEV tPD tODCV3.3 tODCV2.5 tPWH3.3 tPWH2.5 tPWL3.3 tPWL2.5 tORISE tOFALL tLOCK tJR tPJ tPHJ
VCO Frequency Loop Bandwidth Programmable Skew Unit Zero Output Matched-Pair Skew (XQ0, XQ1)[13, 15] Zero Output Skew (All Outputs)[13, 16,17] Output Skew (Rise-Rise, Fall-Fall, Same Class Outputs)[13, 18] Output Skew (Rise-Fall, Nominal-Inverted, Divided-Divided)[13, 18] Output Skew (Rise-Rise, Fall-Fall, Different Class Outputs)[13, 18] Output Skew (Rise-Fall, Nominal-Divided, Divided-Inverted)[13, 18] Device-to-Device Skew[14, 19] Propagation Delay, REF Rise to FB Rise Output Duty Cycle Variation at 3.3V[20] Output Duty Cycle Variation at 2.5V[20] Output HIGH Time Variation at 3.3V[21] Output HIGH Time Variation at 2.5V[21] Output LOW Time Variation at 3.3V[21] Output LOW Time Variation at 2.5V[21] Output Rise Time[21, 22] Output Fall Time[21, 22] PLL Lock Time[23] Cycle-to-Cycle Output Jitter RMS[14] Peak-to-Peak[14] Period Jitter RMS[14] Peak-to-Peak[14] Phase Jitter Peak-to-Peak[14]
MHz MHz ns ns ns ns ns ns ns ns % % % % % % ns ns ms ps ps ps ps ps
Notes: 12. Test measurement levels for the CY7C9925 are TTL levels (1.5V to 1.5V). Test conditions assume signal transition times of 2 ns or less and output loading as shown in the AC Test Loads and Waveforms unless otherwise specified. 13. SKEW is defined as the time between the earliest and the latest output transition among all outputs for which the same tU delay has been selected when all are loaded with 30 pF and terminated with TTLAC Test Load. 14. Guaranteed by statistical correlation. Tested initially and after any design or process changes that may affect these parameters. 15. tSKEWPR is defined as the skew between a pair of outputs (XQ0 and XQ1) when all eight outputs are selected for 0tU. 16. tSKEW0 is defined as the skew between outputs when they are selected for 0tU. Other outputs are divided or inverted but not shifted. 17. CL=0 pF. For CL=30 pF, tSKEW0=0.35 ns. 18. There are three classes of outputs: Nominal (multiple of tU delay), Inverted (4Q0 and 4Q1 only with 4F0 = 4F1 = HIGH), and Divided (3Qx and 4Qx only in Divide-by-2 or Divide-by-4 mode). 19. tDEV is the output-to-output skew between any two devices operating under the same conditions (VCC ambient temperature, air flow, etc.) 20. tODCV is measure at VCCN/2. 21. Specified with outputs loaded with 30 pF for the CY7C9925 devices. Devices are terminated through 50 to VCC/2.tPWH is measured at 2.0V. tPWL is measured at 0.8V for 3.3V power supply. tPWH is measured at 1.7V. tPWL is measured at 0.7V for 2.5V power supply. 22. tORISE and tOFALL measured between 0.8V and 2.0V for 3.3V power supply. tORISE and tOFALL measured between 0.7V and 1.7V for 2.5V power supply 23. tLOCK is the time that is required before synchronization is achieved. This specification is valid only after VCC is stable and within normal operating limits. This parameter is measured from the application of a new signal or frequency at REF or FB until tPD is within specified limits.
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PRELIMINARY
AC Timing Diagrams
tREF tRPWH REF tPD tODCV tRPWL
CY7C9925
tODCV
FB tJR Q
tSKEWPR, tSKEW0,1 OTHER Q
tSKEWPR, tSKEW0,1
tSKEW2 INVERTED Q tSKEW3,4 tSKEW3,4 REF DIVIDED BY 2 tSKEW1,3, 4 REF DIVIDED BY 4
tSKEW2
tSKEW3,4
tSKEW2,4
Ordering Information
Ordering Code CY7C9925LFXC CY7C9925LFXT CY7C9925LFXI CY7C9925LFXIT 32-QFN package 32-QFN package - Tape and Reel 32-QFN package 32-QFN package - Tape and Reel Package Type Operating Range Commercial, 0C to 70C Commercial,0C to 70C Industrial, -40C to 85C Industrial, -40C to 85C
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PRELIMINARY
Package Drawing and Dimensions
32-Lead QFN (5 x 5 mm) LF32A
CY7C9925
51-85188-**
All product and company names mentioned in this document are trademarks of their respective holders.
Document #: 38-07688 Rev. **
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(c) Cypress Semiconductor Corporation, 2004. The information contained herein is subject to change without notice. Cypress Semiconductor Corporation assumes no responsibility for the use of any circuitry other than circuitry embodied in a Cypress product. Nor does it convey or imply any license under patent or other rights. Cypress products are not warranted nor intended to be used for medical, life support, life saving, critical control or safety applications, unless pursuant to an express written agreement with Cypress. Furthermore, Cypress does not authorize its products for use as critical components in life-support systems where a malfunction or failure may reasonably be expected to result in significant injury to the user. The inclusion of Cypress products in life-support systems application implies that the manufacturer assumes all risk of such use and in doing so indemnifies Cypress against all charges.
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Document History Page
Document Title: CY7C9925 3.3V/2.5V Programmable Skew Clock Buffer Document Number: 38-07688 REV. ** ECN NO. 236309 Issue Date See ECN Orig. of Change RGL New Data Sheet Description of Change
CY7C9925
Document #: 38-07688 Rev. **
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