W152 Spread Aware™, Eight Output Zero Delay Buffer Features Output to Output Skew: Between Banks ..................... 215 ps • Spread Aware™—designed to work with SSFTG reference signals • Two banks of four outputs each • Configuration options to halve, double, or quadruple the reference frequency refer to Table 1 to determine the specific option which meets your multiplication needs • Outputs may be three-stated • Available in 16-pin SOIC package • Extra strength output drive available (-11/-12 versions) • Contact factory for availability information on 16-pin TSSOP Output to Output Skew: Within Banks (Refer to Figure 4) ...................................................100 ps Total Timing Budget Impact: ........................................ 555 ps Max. Phase Error Variation: ......................................±225 ps Tracking Skew:...........................................................±130 ps Table 1. Configuration Options Device W152-1/11 Feedback Signal QA0:3 QB0:3 QA0:3 or QB0:3 REFx1 REFx1 W152-2/12[2] QA0:3 REFx1 REF/2 [2] QB0:3 REFx2 REFx1 QA0:3 REFx2 REFx1 W152-2/12 Key Specifications [1] W152-3 Operating Voltage: ............................................... 3.3V±10% W152-3 QB0:3 REFx4 REFx2 Operating Range: .................... 15 MHz < fOUTQA < 140 MHz W152-4 QA0:3 or QB0:3 REFx2 REFx2 Cycle-to-Cycle Jitter: (Refer to Figure 3) .................... 225 ps Cycle-to-Cycle Jitter: Frequency Range 25 to140 MHz ......................................................... 125 ps Notes: 1. W152-11 has stronger output drive than the W152-1. 2. W152-12 has stronger output drive than the W152-2. Block Diagram Pin Configuration (present on the -3 and -4 only) FBIN REF ÷2 PLL MUX QA0 QA1 QA2 SEL0 QA3 ÷2 REF 1 16 FBIN QA0 2 15 QA3 QA1 3 14 QA2 VDD 4 13 VDD GND 5 12 GND QB0 6 11 QB3 QB1 7 10 QB2 SEL1 8 9 SEL0 QB0 SEL1 QB1 QB2 (present on the -2, -12, and -3 only) QB3 Spread Aware is a trademark of Cypress Semiconductor Corporation. Cypress Semiconductor Corporation • 3901 North First Street • San Jose • CA 95134 • 408-943-2600 June 14, 2000, rev. *B W152 Pin Definitions Pin No. Pin Type REF 1 I Reference Input: The output signals QA0:3 through QB0:3 will be synchronized to this signal unless the device is programmed to bypass the PLL. FBIN 16 I Feedback Input: When programmed to zero delay buffer mode, this input must be fed by one of the outputs (QA0:3 or QB0:3) to ensure proper functionality. If the trace between FBIN and the output pin being used for feedback is equal in length to the traces between the outputs and the signal destinations, then the signals received at the destinations will be synchronized to the REF signal input. QA0:3 2, 3, 14, 15 O Outputs from Bank A: The frequency of the signals provided by these pins is determined by the feedback signal connected to FBIN, and the specific W152 option being used. See Table 2. QB0:3 6, 7, 10, 11 O Outputs from Bank B: The frequency of the signals provided by these pins is determined by the feedback signal connected to FBIN, and the specific W152 option being used. See Table 2. VDD 4, 13 P Power Connections: Connect to 3.3V. Use ferrite beads to help reduce noise for optimal jitter performance. GND 5, 12 G Ground Connections: Connect all grounds to the common system ground plane. SEL0:1 9, 8 I Function Select Inputs: Tie to VDD (HIGH, 1) or GND (LOW, 0) as desired per Table 2. Pin Name Pin Description Overview Functional Description The W152 products are eight-output zero delay buffers. A Phase-Locked Loop (PLL) is used to take a time-varying signal and provide eight copies of that same signal out. The external feedback to the PLL provides outputs in phase with the reference inputs. Logic inputs provide the user the ability to turn off one or both banks of clocks when not in use, as described in Table 2. Disabling a bank of unused outputs will reduce jitter and power consumption, and will also reduce the amount of EMI generated by the W152. Internal dividers exist in some options allowing the user to get a simple multiple (/2, x2, x4) of the reference input, for details see Table 1. Because the outputs are separated into two banks, it is possible to provide some combination of these multiples at the same time. These same inputs allow the user to bypass the PLL entirely if so desired. When this is done, the device no longer acts as a zero delay buffer, it simply reverts to a standard eight-output clock driver. The W152 PLL enters an auto power-down mode when there are no rising edges on the REF input. In this mode, all outputs are three-stated and the PLL is turned off. Spread Aware Many systems being designed now utilize a technology called Spread Spectrum Frequency Timing Generation. Cypress has been one of the pioneers of SSFTG development, and we designed this product so as not to filter off the Spread Spectrum feature of the Reference input, assuming it exists. When a zero delay buffer is not designed to pass the SS feature through, the result is a significant amount of tracking skew which may cause problems in systems requiring synchronization. Table 2. Input Logic For more details on Spread Spectrum timing technology, please see the Cypress application note titled, “EMI Suppression Techniques with Spread Spectrum Frequency Timing Generator (SSFTG) ICs.” 2 SEL1 SEL0 QA0:3 QB0:3 0 0 0 1 Active Three-State Active, Utilized 1 0 Active Active Shutdown, Bypassed 1 1 Active Active Active, Utilized Three-State Three-State PLL Shutdown W152 VDD 0.1 µF VDD or GND (for desired operation mode) 1 Ref In FB In 16 2 QA0 QA3 15 3 QA1 QA2 14 4 Power Power 13 5 Ground Ground 12 6 QB0 QB3 11 7 QB1 QB2 10 8 SEL1 SEL0 9 See Note 3 VDD Ferrite Bead 3.3V Supply 0.1 µF 10 µF VDD or GND (for desired operation mode) Figure 1. Schematic[3] Note: 3. Pin 16 needs to be connected to one of the outputs from either bank A or bank B, it should not be connected to both. Pins 2 and 10 are shown here as examples. None of the outputs should be considered aas preferred for the feedback path. some other device. This implementation can be applied to any device (ASIC, multiple output clock buffer/driver, etc.) which is put into the feedback path. How to Implement Zero Delay Typically, zero delay buffers (ZDBs) are used because a designer wants to provide multiple copies of a clock signal in phase with each other. The whole concept behind ZDBs is that the signals at the destination chips are all going HIGH at the same time as the input to the ZDB. In order to achieve this, layout must compensate for trace length between the ZDB and the target devices. The method of compensation is described below. Referring to Figure 2, if the traces between the ASIC/buffer and the destination of the clock signal(s) (A) are equal in length to the trace between the buffer and the FBIN pin, the signals at the destination(s) device will be driven HIGH at the same time the Reference clock provided to the ZDB goes HIGH. Synchronizing the other outputs of the ZDB to the outputs form the ASIC/Buffer is more complex however, as any propagation delay in the ASIC/Buffer must be accounted for. External feedback is the trait that allows for this compensation. The PLL on the ZDB will cause the feedback signal to be in phase with the reference signal. When laying out the board, match the trace lengths between the output being used for feedback and the FBIN input to the PLL. Reference Signal If it is desirable to either add a little delay, or slightly precede the input signal, this may also be affected by either making the trace to the FBIN pin a little shorter or a little longer than the traces to the devices being clocked. Feedback Input Zero Delay Buffer ASIC/ Buffer Inserting Other Devices in Feedback Path Figure 2. 6 Output Buffer in the Feedback Path Another nice feature available due to the external feedback is the ability to synchronize signals up to the signal coming from 3 A W152 Absolute Maximum Ratings above those specified in the operating sections of this specification is not implied. Maximum conditions for extended periods may affect reliability. Stresses greater than those listed in this table may cause permanent damage to the device. These represent a stress rating only. Operation of the device at these or any other conditions . Parameter Description Rating Unit V VDD, VIN Voltage on any pin with respect to GND –0.5 to +7.0 –65 to +150 °C 0 to +70 °C –55 to +125 °C 0.5 W TSTG Storage Temperature TA Operating Temperature TB Ambient Temperature under Bias PD Power Dissipation DC Electrical Characteristics: TA =0°C to 70°C, VDD = 3.3V ±10% Parameter Description Test Condition Min. Typ. Max. Unit 40 mA 0.8 V IDD Supply Current VIL Input Low Voltage VIH Input High Voltage VOL Output Low Voltage IOL = 12 mA (-11, -12) IOL = 8 mA (-1, -2, -3, -4) VOH Output High Voltage IOH = 12 mA (-11, -12) IOH = 8 mA (-1, -2, -3, -4) IIL Input Low Current VIN = 0V 50 µA IIH Input High Current VIN = VDD 50 µA Max. Unit Unloaded, 100 MHz 2.0 V 0.4 2.4 V V AC Electrical Characteristics: TA = 0°C to +70°C, VDD = 3.3V ±10% Parameter Description Test Condition Min. Typ. fIN Input Frequency Note 3 15 140 MHz fOUT Output Frequency 15-pF load[8] 15 140 MHz tR Output Rise Time (-1, -2, -3, -4) 0.8V to 0.8V, 15-pF load 2.5 ns Output Rise Time (-11, -12) 0.8V to 0.8V, 15-pF load 1.5 ns Output Fall Time (-1, -2, -3, -4) 2.0V to 0.8V, 15-pF load 2.5 ns Output Rise Time (-11, -12) 2.0V to 0.8V, 20-pF load 1.5 ns 4.5 ns 4.5 ns 350 ps 215 ps 55 % tF tICLKR tICLKF 2 2 [4] Input Clock Rise Time [4] Input Clock Fall Time [5, 6] tPD FBIN to REF Skew tSK Output to Output Skew All outputs loaded equally[10] [7, 8] tD Duty Cycle 15-pF load 45 50 tLOCK PLL Lock Time Power supply stable 1.0 ms tJC Jitter, Cycle-to-Cycle Note 9 225 ps Notes: 3. Input frequency is limited by output frequency range and input to output frequency multiplication factor (which is determined by circuit configuration). See Table 1. 4. Longer input rise and fall time will degrade skew and jitter performance. 5. All AC specifications are measured with a 50Ω transmission line. 6. Skew is measured at VDD/2 on rising edges. 7. Duty cycle is measured at VDD/2. 8. For the higher drive -11 and -12, the load is 20 pF. 9. For frequencies above 25 MHz CY - CY = 125 ps. 10. Measured across all outputs. Maximum skew between outputs in the same bank is 100 ps. 4 W152 ps W152 -01 CYCLE - CYCLE JITTER @ 15 pF 1000 900 800 700 600 500 400 300 200 100 0 0 20 40 60 80 100 120 140 FREQUENCY in MHz 07/21/99 W152-a1 Figure 3. Cycle to Cycle Jitter at 15 pF W152 -01 PIN- PIN SKEW @ 15 pF 300 200 ps 100 0 A1 A2 A3 A4 B1 B2 B3 B4 -100 -200 OUTPUT # PIN A1 = REF O7/21/99 a3 Figure 4. Pin to Pin Skew at 15 pF Ordering Information Ordering Code W152 Package Name Option -1, -11, -2, -12, -3, -4 Package Type G X 16-pin SOIC (150 mil) 16-pin TSSOP (4.4 mm) Document #: 38-00786-*B 5 160 W152 Package Diagrams 16-Pin Small Outline Integrated Circuit (SOIC, 150 mils) 6 W152 Package Diagrams (continued) 16-Pin Thin Shrink Small Outline Package (TSSOP, 4.4 mm) © Cypress Semiconductor Corporation, 2000. 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 Semiconductor product. Nor does it convey or imply any license under patent or other rights. Cypress Semiconductor 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 Semiconductor products in life-support systems application implies that the manufacturer assumes all risk of such use and in doing so indemnifies Cypress Semiconductor against all charges.