CY7C4282V CY7C4292V 64K/128Kx9 Low Voltage Deep Sync FIFOs w/ Retransmit & Depth Expansion Features Functional Description • 3.3V operation for low power consumption and easy integration into low-voltage systems • High-speed, low-power, first-in first-out (FIFO) memories • 64K x 9 (CY7C4282V) • 128K x 9 (CY7C4292V) • 0.35 micron CMOS for optimum speed/power • High-speed, Near Zero Latency (True Dual-Ported Memory Cell), 100-MHz operation (10 ns read/write cycle times) • Low power — ICC = 25 mA • • • • • • • • • • The CY7C4282V/92V are high-speed, low-power, first-in firstout (FIFO) memories with clocked read and write interfaces. All devices are 9 bits wide. The CY7C4282V/92V can be cascaded to increase FIFO depth. Programmable features include Almost Full/Almost Empty flags. These FIFOs provide solutions for a wide variety of data buffering needs, including high-speed data acquisition, multiprocessor interfaces, video and communications buffering. These FIFOs have 9-bit input and output ports that are controlled by separate clock and enable signals. The input port is controlled by a free-running clock (WCLK) and a Write Enable pin (WEN). — ISB = 6 mA Fully asynchronous and simultaneous read and write operation Empty, Full, and Programmable Almost Empty and Almost Full status flags Retransmit function Output Enable (OE) pin Independent read and write enable pins Supports free-running 50% duty cycle clock inputs Width Expansion Capability Depth Expansion Capability through token-passing scheme (no external logic required) 64-pin 10x10 STQFP Pin-compatible 3.3V solution for CY7C4282/92 D0 − Retransmit and Synchronous Almost Full/Almost Empty flag features are available on these devices. Depth expansion is possible using the Cascade Input (XI), Cascade Output (XO), and First Load (FL) pins. The XO pin is connected to the XI pin of the next device, and the XO pin of the last device should be connected to the XI pin of the first device. The FL pin of the first device is tied to VSS and the FL pin of all the remaining devices should be tied to VCC When WEN is asserted, data is written into the FIFO on the rising edge of the WCLK signal. While WEN is held active, data is continually written into the FIFO on each cycle. The output port is controlled in a similar manner by a free-running Read Clock (RCLK) and a Read Enable pin (REN). In addition, the CY7C4282V/92V have an Output Enable pin (OE). The read and write clocks may be tied together for single-clock operation or the two clocks may be run independently for asynchronous read/write applications. Clock frequencies up to 67 MHz are achievable. 8 Logic Block Diagram INPUT REGISTER WCLK WEN FLAG PROGRAM REGISTER WRITE CONTROL FF FLAG LOGIC Dual Port RAM Array 64K x 9 128K x 9 WRITE POINTER RS PAE PAF/XO READ POINTER RESET LOGIC THREE-STATE OUTPUT REGISTER FL/RT XI/LD EF EXPANSION LOGIC PAF/XO OE Q0 − Cypress Semiconductor Corporation READ CONTROL • 8 3901 North First Street RCLK REN • San Jose 4282V–1 • CA 95134 • 408-943-2600 October 18, 1999 CY7C4282V CY7C4292V Pin Configuration 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 CY7C4282V CY7C4292V 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 WEN RS D8 D7 D6 N/C N/C N/C N/C N/C N/C N/C D5 D4 D3 D2 64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 WCLK XI/LD GND N/C N/C N/C N/C N/C VCC N/C N/C Q8 Q7 GND Q6 N/C STQFP Top View 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 Q5 Q4 GND Q3 Q2 VCC Q1 Q0 GND N/C FF EF OE GND FL/RT N/C D1 D0 N/C N/C N/C VCC PAF/XO PAE N/C N/C N/C N/C N/C GND REN RCLK 4282V–2 Functional Description (continued) entering or exiting the Empty and Almost Empty states, the flags are updated exclusively by the RCLK. The flags denoting Almost Full, and Full states are updated exclusively by WCLK. The synchronous flag architecture guarantees that the flags maintain their status for at least one cycle The CY7C4282V/92V provides four status pins: Empty, Full, Programmable Almost Empty, and Programmable Almost Full. The Almost Empty/Almost Full flags are programmable to single word granularity. The programmable flags default to Empty+7 and Full−7. All configurations are fabricated using an advanced 0.35µ CMOS technology. Input ESD protection is greater than 2001V, and latch-up is prevented by the use of guard rings. The flags are synchronous, i.e., they change state relative to either the read clock (RCLK) or the write clock (WCLK). When Selection Guide 7C4282V/92V-10 7C4282V/92V-15 7C4282V/92V-25 Maximum Frequency (MHz) 100 66.7 40 Maximum Access Time (ns) 8 10 15 Minimum Cycle Time (ns) 10 15 25 Minimum Data or Enable Set-Up (ns) 3.5 4 6 Minimum Data or Enable Hold (ns) 0 0 1 Maximum Flag Delay (ns) 8 10 15 25 25 25 Active Power Supply Current (ICC) (mA) Commercial Industrial 30 CY7C4282V CY7C4292V Density 64k x 9 128k x 9 Package 64-pin 10x10 TQFP 64-pin 10x10 TQFP 2 CY7C4282V CY7C4292V Pin Definitions Signal Name Description I/O Description D0−8 Data Inputs I Data Inputs for 9-bit bus. Q0−8 Data Outputs O Data Outputs for 9-bit bus. WEN Write Enable I The only write enable when device is configured to have programmable flags. Data is written on a LOW-to-HIGH transition of WCLK when WEN is asserted and FF is HIGH. REN Read Enable I Enables the device for Read operation. REN must be asserted LOW to allow a Read operation. WCLK Write Clock I The rising edge clocks data into the FIFO when WEN is LOW and the FIFO is not Full. When LD is asserted, WCLK writes data into the programmable flag-offset register. RCLK Read Clock I The rising edge clocks data out of the FIFO when REN is LOW and the FIFO is not Empty. When LD is LOW, RCLK reads data out of the programmable flag-offset register. EF Empty Flag O When EF is LOW, the FIFO is empty. EF is synchronized to RCLK. FF Full Flag O When FF is LOW, the FIFO is full. FF is synchronized to WCLK. PAE Programmable Almost Empty O When PAE is LOW, the FIFO is almost empty based on the almost empty offset value programmed into the FIFO. PAE is synchronized to RCLK. PAF/XO Programmable Almost Full/ Expansion Output O Dual-Mode Pin: Cascaded - Connected to XI of next device. Not Cascaded - When PAF is LOW, the FIFO is almost full based on the almost full offset value programmed into the FIFO. PAF is synchronized to WCLK. FL/RT First Load/ Retransmit I Dual-Mode Pin: Cascaded - The first device in the daisy chain will have FL tied to VSS; all other devices will have FL tied to V CC. In standard mode or width expansion, FL is tied to V SS on all devices. Not Cascaded - Retransmit function is available in stand-alone mode by strobing RT. XI/LD Expansion Input/Load I Dual-Mode Pin: Cascaded - Connected to XO of previous device. Not Cascaded - LD is used to write or read the programmable flag offset registers. LD must be asserted LOW during reset to enable standalone or width expansion operation. If programmable offset register access is not required, LD can be tied to RS directly. OE Output Enable I When OE is LOW, the FIFO’s data outputs drive the bus to which they are connected. If OE is HIGH, the FIFO’s outputs are in High Z (high-impedance) state. RS Reset I Resets device to empty condition. A reset is required before an initial read or write operation after power-up. Maximum Ratings Static Discharge Voltage ........................................... >2001V (per MIL-STD-883, Method 3015) (Above which the useful life may be impaired. For user guidelines, not tested.) Latch-Up Current ..................................................... >200 mA Storage Temperature ....................................... −65°C to +150°C Operating Range Ambient Temperature with Power Applied .................................................... −55°C to +125°C Range Ambient Temperature Supply Voltage to Ground Potential..........−0.5V to V CC +0.5V VCC  Commercial 0°C to +70°C 3.3V + /−300mV −40°C to +85°C 3.3V + /−300mV DC Voltage Applied to Outputs in High Z State ..............................................−0.5V to VCC+0.5V Industrial DC Input Voltage .........................................−0.5V to V CC +0.5V Output Current into Outputs (LOW) ............................. 20 mA Notes: 1. TA is the “instant on” case temperature. 2. VCC Range for commercial -10 ns is 3.3V ± 150 mV. 3  CY7C4282V CY7C4292V Electrical Characteristics Over the Operating Range Parameter Description 7C4282V/92V -10 7C4282V/92V -15 7C4282V/92V -25 Test Conditions Min. Min. Min. 2.4 Max. Max. VOH Output HIGH Voltage VCC = Min., IOH = −1.0 mA VCC = 3.0V, IOH = −2.0 mA VOL Output LOW Voltage VCC = Min., IOL = 4.0 mA VCC = 3.0V, IOL = 8.0 mA VIH Input HIGH Voltage 2.0 VCC 2.0 VCC VIL Input LOW Voltage −0.5 0.8 −0.5 IIX Input Leakage Current VCC = Max. −10 +10 IOZL IOZH Output OFF, High Z Current OE > VIH, VSS < VO < V CC −10 +10 ICC1 Active Power Supply Current Com’l Average Standby Current Com’l ISB 2.4 0.4 Max. 2.4 Unit V 0.4 0.4 V 2.0 VCC V 0.8 −0.5 0.8 V −10 +10 −10 +10 µA −10 +10 −10 +10 µA 25 mA 25 25 Ind 30 6 mA 6 Ind 6 mA 6 mA Capacitance Parameter Description CIN Input Capacitance COUT Output Capacitance Test Conditions TA = 25°C, f = 1 MHz, VCC = 3.3V Max. Unit 5 pF 7 pF AC Test Loads and Waveforms (-15 , -25) [6, 7] R1=330Ω ALL INPUT PULSES 3.3V OUTPUT 3.0V R2=510Ω CL GND ≤ 3 ns INCLUDING JIG AND SCOPE Equivalent to: 90% 10% 90% 10% ≤ 3 ns 4282V–4 THÉVENIN EQUIVALENT 200 Ω OUTPUT 4282V–5 2.0V AC Test Loads and Waveforms (-10) ALL INPUT PULSES VCC/2 3.0V 90% 10% 50Ω GND I/O ≤ 3 ns Z0=50Ω 90% 10% ≤ 3 ns 4282V–5 Notes: 3. Input signals switch from 0V to 3V with a rise/fall time of less than 3 ns, clocks and clock enables switch at maximum frequency 20 MHz, while data inputs switch at 10 MHz. Outputs are unloaded. 4. All inputs = VCC − 0.2V, except WCLK and RCLK (which are switching at frequency = 0 MHz). All outputs are unloaded. 5. Tested initially and after any design or process changes that may affect these parameters. 6. CL = 30 pF for all AC parameters except for tOHZ. 7. CL = 5 pF for tOHZ. 4 CY7C4282V CY7C4292V Switching Characteristics Over the Operating Range Parameter Description 7C4282V/92V -10 7C4282V/92V -15 7C4282V/92V -25 Min. Min. Min. Max. 100 Max. Unit 40 MHz 15 ns tS Clock Cycle Frequency tA Data Access Time 2 tCLK Clock Cycle Time 10 15 25 ns tCLKH Clock HIGH Time 4.5 6 10 ns tCLKL Clock LOW Time 4.5 6 10 ns tDS Data Set-Up Time 3.5 4 6 ns tDH Data Hold Time 0 0 1 ns tENS Enable Set-Up Time 3.5 4 6 ns tENH Enable Hold Time 0 0 1 ns tRS Reset Pulse Width 10 15 25 ns tRSS Reset Set-Up Time 8 10 15 ns tRSR Reset Recovery Time 8 10 15 ns tRSF Reset to Flag and Output Time tPRT Retransmit Pulse Width tRTR Retransmit Recovery Time 8 66.7 Max. 2 10  10 2 15 25 ns 60 60 60 ns 90 90 90 ns 0 0 0 ns tOLZ Output Enable to Output in Low Z tOE Output Enable to Output Valid 3 7 3 10 3 12 ns tOHZ Output Enable to Output in High Z 3 7 3 8 3 12 ns tWFF Write Clock to Full Flag 8 10 15 ns tREF Read Clock to Empty Flag 8 10 15 ns tPAF Clock to Programmable Almost-Full Flag 8 10 15 ns tPAE Clock to Programmable Almost-Full Flag 8 10 15 ns tSKEW1 Skew Time between Read Clock and Write Clock for Empty Flag and Full Flag 5 6 10 ns tSKEW2 Skew Time between Read Clock and Write Clock for Almost-Empty Flag and Almost-Full Flag 10 15 18 ns Notes: 8. Pulse widths less than minimum values are not allowed. 9. Values guaranteed by design, not currently tested. 5 CY7C4282V CY7C4292V Switching Waveforms Write Cycle Timing tCLK tCLKH tCLKL WCLK tDS tDH D0 –D17 tENS tENH WEN NO OPERATION tWFF tWFF FF tSKEW1  RCLK REN 4282V–6 Read Cycle Timing tCLK tCLKH tCLKL RCLK tENS tENH REN NO OPERATION tREF tREF EF tA Q0 –Q17 VALID DATA tOLZ tOHZ tOE OE tSKEW1  WCLK WEN 4282V–7 Notes: 10. tSKEW1 is the minimum time between a rising RCLK edge and a rising WCLK edge to guarantee that FF will go HIGH during the current clock cycle. If the time between the rising edge of RCLK and the rising edge of WCLK is less than tSKEW1, then FF may not change state until the next WCLK rising edge. 11. tSKEW1 is also the minimum time between a rising WCLK edge and a rising RCLK edge to guarantee that EF will go HIGH during the current clock cycle. It the time between the rising edge of WCLK and the rising edge of RCLK is less than tSKEW2, then EF may not change state until the next RCLK rising edge. 6 CY7C4282V CY7C4292V Switching Waveforms (continued) Reset Timing  tRSS  LD tRS RS tRSR REN, WEN tRSF EF,PAE tRSF FF,PAF  tRSF OE=1 Q0 – Q8 OE=0 4282V–8 First Data Word Latency after Reset with Simultaneous Read and Write WCLK tDS D0 –D8 D0 (FIRSTVALID WRITE) D1 tENS D2 D3 D4  tFRL WEN tSKEW1 RCLK tREF EF REN  tA Q0 –Q8 tA D0 D1 tOLZ tOE OE 4282V–9 Notes: 12. The clocks (RCLK, WCLK) can be free-running during reset. 13. For standalone or width expansion configuration only. 14. After reset, the outputs will be LOW if OE = 0 and three-state if OE=1. 15. When t SKEW1 > minimum specification, tFRL (maximum) = tCLK + tSKEW2. When tSKEW1 < minimum specification, tFRL (maximum) = either 2*tCLK + tSKEW1 or tCLK + tSKEW1. The Latency Timing applies only at the Empty Boundary (EF = LOW). 16. The first word is available the cycle after EF goes HIGH, always. 7 CY7C4282V CY7C4292V Switching Waveforms (continued) Empty Flag Timing WCLK tDS tDS DATA WRITE 2 DATA WRITE 1 D0 –D8 tENH tENS tENH tENS WEN tFRL  tFRL  RCLK tREF tREF tSKEW1 tREF tSKEW2 EF REN LOW OE tA DATA IN OUTPUT REGISTER Q0 –Q8 DATA READ 4282V–10 Full Flag Timing NO WRITE NO WRITE WCLK tSKEW1  tDS DATA WRITE tSKEW1 DATA WRITE D0 –D8 tWFF tWFF tWFF FF WEN RCLK tENH REN OE tENH tENS tENS LOW tA Q0 –Q8 tA DATA READ DATA IN OUTPUT REGISTER NEXT DATA READ 4282V–11 8 CY7C4282V CY7C4292V Switching Waveforms (continued) Programmable Almost Empty Flag Timing tCLKL tCLKH WCLK tENS tENH WEN Note 18 PAE tSKEW2  N + 1 WORDS IN FIFO tPAE Note 19 t PAE RCLK tENS tENS tENH REN 4282V–12 Programmable Almost Full Flag Timing tCLKH tCLKL Note 20 WCLK tENS tENH WEN tPAF PAF FULL − M WORDS IN FIFO  FULL − (M+1)WORDS IN FIFO tSKEW2  tPAF RCLK tENS tENS tENH REN 4282V–13 Notes: 17. tSKEW2 is the minimum time between a rising WCLK and a rising RCLK edge for PAE to change state during that clock cycle. If the time between the edge of WCLK and the rising RCLK is less than tSKEW2, then PAE may not change state until the next RCLK. 18. PAE offset= n. 19. If a read is performed on this rising edge of the read clock, there will be Empty + (n−1) words in the FIFO when PAE goes LOW 20. If a write is performed on this rising edge of the write clock, there will be Full − (m−1) words of the FIFO when PAF goes LOW. 21. 64K − m words for CY7C4282V, 128K − m words for CY4292V. 22. tSKEW2 is the minimum time between a rising RCLK edge and a rising WCLK edge for PAF to change during that clock cycle. If the time between the rising edge of RCLK and the rising edge of WCLK is less than tSKEW2, then PAF may not change state until the next WCLK. 9 CY7C4282V CY7C4292V Switching Waveforms (continued) Write Programmable Registers tCLK tCLKL tCLKH WCLK tENS tENH LD tENS WEN tDS tDH D0 –D8 PAE OFFSET LSB PAE OFFSET MSB PAF OFFSET LSB PAF OFFSET MSB 4282V–14 Read Programmable Registers tCLK tCLKL tCLKH RCLK tENS LD tENH tENS PAF OFFSET MSB REN tA UNKNOWN Q0 –Q15 PAE OFFSET LSB PAE OFFSET MSB PAF OFFSET LSB 4282V–15 Retransmit Timing [23, 24, 25] FL/RT tPRT tRTR REN/WEN EF/FF 4282V–16 Notes: 23. Clocks are free-running in this case. 24. The flags may change state during Retransmit as a result of the offset of the read and write pointers, but flags will be valid at tRTR. 25. For the synchronous PAE and PAF flags an appropriate clock cycle is necessary after tRTR to update these flags. 10 CY7C4282V CY7C4292V register again. Figure 1 shows the registers sizes and default values for the various device types. Architecture The CY7C4282V/92V consists of an array of 64K to 128K words of 9 bits each (implemented by a dual-port array of SRAM cells), a read pointer, a write pointer, control signals (RCLK, WCLK, REN, WEN, RS), and flags (EF, PAE, PAF, FF). 64k x 9 128kx 9 0 7 8 8 Empty Offset (LSB) Reg. Default Value = 007h Resetting the FIFO Upon power-up, the FIFO must be reset with a Reset (RS) cycle. This causes the FIFO to enter the Empty condition signified by EF being LOW. All data outputs (Q0 − 8) go LOW tRSF after the rising edge of RS. In order for the FIFO to reset to its default state, the user must not read or write while RS is LOW. All flags are guaranteed to be valid tRSF after RS is taken LOW. Empty Offset (LSB) Reg. Default Value = 007h 0 7 8 0 7 0 8 (MSB) Default Value = 000h 0 7 8 (MSB) Default Value = 000h 8 Full Offset (LSB) Reg Default Value = 007h During reset of the FIFO, the state of the XI/LD pin determines if depth expansion operation is used. For depth expansion operation, XI/LD is tied to XO of the next device. See “Depth Expansion Configuration” and Figure 3. For standalone or width expansion configuration, the XI/LD pin must be asserted LOW during reset. Full Offset (LSB) Reg Default Value = 007h 0 7 8 0 7 0 8 (MSB) Default Value = 000h There is a 0-ns hold time requirement for the XI/LD configuration at the RS deassertion edge. This allows the user to tie XI/LD to RS directly for applications that do not require access to the flag offset registers. (MSB) Default Value = 000h 4282V–16 Figure 1. Offset Register Location and Default Values It is not necessary to write to all the offset registers at one time. A subset of the offset registers can be written; then by bringing the LD input HIGH, the FIFO is returned to normal read and write operation. The next time LD is brought LOW, a write operation stores data in the next offset register in sequence. FIFO Operation When the WEN is asserted LOW and FF is HIGH, data present on the D0 −8 pins is written into the FIFO on each rising edge of the WCLK signal. Similarly, when the REN is asserted LOW and EF is HIGH, data in the FIFO memory will be presented on the Q 0−8 outputs. New data will be presented on each rising edge of RCLK while REN is active. REN must set up tENS before RCLK for it to be a valid read function. WEN must occur tENS before WCLK for it to be a valid write function. The contents of the offset registers can be read to the data outputs when LD is LOW and REN is LOW. LOW-to-HIGH transitions of RCLK read register contents to the data outputs. Writes and reads should not be performed simultaneously on the offset registers. Programmable Flag (PAE, PAF) Operation An Output Enable (OE) pin is provided to three-state the Q 0−8 outputs when OE is asserted. When OE is enabled (LOW), data in the output register will be available to the Q0−8 outputs after tOE. If devices are cascaded, the OE function will only output data on the FIFO that is read enabled. Whether the flag offset registers are programmed as described in Table 1 or the default values are used, the programmable Almost Empty flag (PAE) and programmable Almost Full flag (PAF) states are determined by their corresponding offset registers and the difference between the read and write pointers. The FIFO contains overflow circuitry to disallow additional writes when the FIFO is full, and underflow circuitry to disallow additional reads when the FIFO is empty. An empty FIFO maintains the data of the last valid read on its Q0−8 outputs even after additional reads occur. Table 1. Writing the Offset Registers WCLK  LD WEN Programming 0 0 When LD is held LOW during Reset, this pin is the Load Enable (LD) for flag offset programming. In this configuration, LD can be used to access the four 9-bit offset registers contained in the CY7C4282V/92V for writing or reading data to these registers. 0 1 No Operation 1 0 Write Into FIFO 1 1 No Operation When the device is configured for programmable flags and both LD and WEN are LOW, the first LOW-to-HIGH transition of WCLK writes data from the data inputs to the empty offset least significant bit (LSB) register. The second, third, and fourth LOW-to-HIGH transitions of WCLK store data in the empty offset most significant bit (MSB) register, full offset LSB register, and full offset MSB register, respectively, when LD and WEN are LOW. The fifth LOW-to-HIGH transition of WCLK while LD and WEN are LOW writes data to the empty LSB Selection Empty Offset (LSB) Empty Offset (MSB) Full Offset (LSB) Full Offset (MSB) Note: 26. The same selection sequence applies to reading from the registers. REN is enabled and a read is performed on the LOW-to-HIGH transition of RCLK. 11 CY7C4282V CY7C4292V The number formed by the empty offset least significant bit register and empty offset most significant bit register is referred to as n and determines the operation of PAE. PAE is synchronized to the LOW-to-HIGH transition of RCLK by one flip-flop and is LOW when the FIFO contains n or fewer unread words. PAE is set HIGH by the LOW-to-HIGH transition of RCLK when the FIFO contains (n+1) or greater unread words. Full Flag The Full Flag (FF) will go LOW when device is Full. Write operations are inhibited whenever FF is LOW regardless of the state of WEN. FF is synchronized to WCLK, i.e., it is exclusively updated by each rising edge of WCLK. Empty Flag The number formed by the full offset least significant bit register and full offset most significant bit register is referred to as m and determines the operation of PAF. PAF is synchronized to the LOW-to-HIGH transition of WCLK by one flip-flop and is set LOW when the number of unread words in the FIFO is greater than or equal to CY7C4282V (64K − m) and CY7C4292V (128K − m). PAF is set HIGH by the LOW-toHIGH transition of WCLK when the number of available memory locations is greater than m. The Empty Flag (EF) will go LOW when the device is empty. Read operations are inhibited whenever EF is LOW, regardless of the state of REN. EF is synchronized to RCLK, i.e., it is exclusively updated by each rising edge of RCLK. Programmable Almost Empty/Almost Full Flag The CY7C4282V/92V features programmable Almost Empty and Almost Full Flags. Each flag can be programmed (described in the Programming section) a specific distance from the corresponding boundary flags (Empty or Full). When the FIFO contains the number of words or fewer for which the flags have been programmed, the PAF or PAE will be asserted, signifying that the FIFO is either Almost Full or Almost Empty. See Table 2 for a description of programmable flags. Flag Operation The CY7C4282V/92V devices provide four flag pins to indicate the condition of the FIFO contents. All flags operate synchronously. Table 2. Status Flags Number of Words in FIFO CY7C4282V 0 CY7C4292V 0   FF PAF PAE EF H H L L 1 to n 1 to n H H L H (n+1) to (65536 − (m+1)) (n+1) to (131072 − (m+1)) H H H H (65536 − m) (131072 − m) H L H H L L H H  to 65535 65536  to 131071 131072 Notes: 27. n = Empty Offset (n=7 default value). 28. m = Full Offset (m=7 default value). 12 CY7C4282V CY7C4292V Retransmit ten to the FIFO after activation of RT are transmitted also. The full depth of the FIFO can be repeatedly retransmitted. The retransmit feature is beneficial when transferring packets of data. It enables the receipt of data to be acknowledged by the receiver and retransmitted if necessary. Width Expansion Configuration Word width may be increased simply by connecting the corresponding input control signals of multiple devices. A composite flag should be created for each of the end-point status flags (EF and FF). The partial status flags (PAE and PAF) can be detected from any one device. Figure 2 demonstrates a 18-bit word width by using two CY7C4282V/92V. Any word width can be attained by adding additional CY7C4282V/92V. The Retransmit (RT) input is active in the standalone and width expansion modes. The retransmit feature is intended for use when a number of writes equal to or less than the depth of the FIFO have occurred and at least one word has been read since the last RS cycle. A HIGH pulse on RT resets the internal read pointer to the first physical location of the FIFO. WCLK and RCLK may be free running but must be disabled during and tRTR after the retransmit pulse. With every valid read cycle after retransmit, previously accessed data is read and the read pointer is incremented until it is equal to the write pointer. Flags are governed by the relative locations of the read and write pointers and are updated during a retransmit cycle. Data writ- When the CY7C4282V/92V is in a Width Expansion Configuration, the Read Enable (REN) control input can be grounded (see Figure 2). In this configuration, the Load (LD) pin is set to LOW at Reset so that the pin operates as a control to load and read the programmable flag offsets. RESET (RS) DATA IN (D) 18 RESET (RS) 9 9 READ CLOCK (RCLK) WRITE CLOCK (WCLK) READ ENABLE (REN) WRITE ENABLE (WEN) OUTPUT ENABLE (OE) LOAD (LD) PROGRAMMABLE(PAE) 7C4282V 7C4292V HALF FULL FLAG (HF) PROGRAMMABLE (PAF) 7C4282V 7C4292V EMPTY FLAG (EF) FF FF EF EF 9 FULL FLAG (FF) DATA OUT (Q) 18 9 FIRST LOAD (FL) EXPANSION IN (XI) FIRST LOAD (FL) EXPANSION IN (XI) 4282V–17 Figure 2. Block Diagram of 64Kx9/128Kx9 Low-Voltage Deep Sync FIFO Memory Used in a Width Expansion Configuration 13 CY7C4282V CY7C4292V Depth Expansion Configuration 1. The first device must be designated by grounding the First Load (FL) control input. The CY7C4282V/92V can easily be adapted to applications requiring more than 64K/128K words of buffering. Figure 3 shows Depth Expansion using three CY7C4282V/92Vs. Maximum depth is limited only by signal loading. Follow these steps: 2. All other devices must have FL in the HIGH state. 3. The Expansion Out (XO) pin of each device must be tied to the Expansion In (XI) pin of the next device. 4. EF and FF composite flags are created by ORing together each individual respective flag. XO RCLK WCLK REN WEN OE RS 7C4282V D 7C4292V Q VCC FL FF EF XI XO RCLK WCLK REN WEN OE RS 7C4282V 7C4292V Q D DATA IN (D) DATA OUT (Q) VCC FL FF EF XI WRITECLOCK (WCLK) WCLK WRITEENABLE (WEN) XO RCLK WEN READ CLOCK (RCLK) READ ENABLE (REN) REN RESET (RS) OUTPUTENABLE (OE) RS 7C4282V OE D 7C4292V Q FF FF FL EF EF XI FIRST LOAD (FL) 4282V–25 Figure 3. Block Diagram of 64Kx9/128Kx9 Low-Voltage Deep Sync FIFO Memory with Programmable Flags used in Depth Expansion Configuration 14 CY7C4282V CY7C4292V Ordering Information 64K x 9 Low Voltage Deep Sync FIFO Speed (ns) Ordering Code Package Name Package Type Operating Range 10 CY7C4282V-10ASC A64 64-Lead 10x10 Thin Quad Flatpack Commercial 15 CY7C4282V-15ASC A64 64-Lead 10x10 Thin Quad Flatpack Commercial CY7C4282V-15ASI A64 64-Lead 10x10 Thin Quad Flatpack Industrial CY7C4282V-25ASC A64 64-Lead 10x10 Thin Quad Flatpack Commercial 25 128K x 9 Low Voltage Deep Sync FIFO Speed (ns) Ordering Code Package Name Package Type Operating Range 10 CY7C4292V-10ASC A64 64-Lead 10x10 Thin Quad Flatpack Commercial 15 CY7C4292V-15ASC A64 64-Lead 10x10 Thin Quad Flatpack Commercial CY7C4292V-15ASI A64 64-Lead 10x10 Thin Quad Flatpack Industrial CY7C4292V-25ASC A64 64-Lead 10x10 Thin Quad Flatpack Commercial 25 Document #: 38-00657-B Package Diagram 64-Pin Thin Plastic Quad Flat Pack (10 x 10 x 1.4 mm) A64 51-85051-A © Cypress Semiconductor Corporation, 1999. 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.