Features: • 3.3V operation for low power consumption and easy integration into low-voltage systems
• High-speed, low-power, first-in first-out (FIFO) memories
• 64 x 18 (CY7C4425V)
• 256 x 18 (CY7C4205V)
• 512 x 18 (CY7C4215V)
• 1K x 18 (CY7C4225V)
• 2K x 18 (CY7C4235V)
• 4K x 18 (CY7C4245V)
• 0.65 CMOS
• High-speed 67-MHz operation (15-ns read/write cycle times)
• Low power
-ICC = 30 mA
• 5V tolerant inputs (VIH MAX = 5V)
• Fully asynchronous and simultaneous read and write operation
• Empty, Full, Half Full, and programmable Almost Empty and Almost Full status flags
• TTL compatible
• 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
• 64-pin 14x14 TQFP and 64-pin 10x10 STQFPPinout
Specifications(Above which the useful life may be impaired. For user guidelines, not tested.)
Storage Temperature ....................................−65°C to +150°C
Ambient Temperature with
Power Applied.................................................−55°C to +125°C
Supply Voltage to Ground Potential..................−0.5V to +5.0V
DC Voltage Applied to Outputs
in High Z State............................................. −0.5V to VCC+0.5V
DC Input Voltage .................................................... −0.5V to +5V
Output Current into Outputs (LOW) ............................. 20 mA
Static Discharge Voltage .......................................... >2001V
(per MIL-STD-883, Method 3015)
Latch-Up Current..................................................... >200 mADescriptionThe CY7C42X5V are high-speed, low-power, first-in first-out (FIFO) memories with clocked read and write interfaces. The CY7C42X5V are 18 bits wide. The CY7C42X5V 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, and communications buffering.
The CY7C42X5V have 18-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).
When WEN is asserted, data is written into the FIFO of the CY7C42X5V 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 CY7C42X5V 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 66 MHz are achievable.
Retransmit and Synchronous Almost Full/Almost Empty flag features are available on the CY7C42X5V.
Depth expansion of the CY7C42X5V is possible using the Cascade Input (WXI, RXI), Cascade Output (WXO, RXO), and First Load (FL) pins.
The WXO and RXO pins are connected to the WXI andRXI pins of the next device, and the WXO and RXO pins of the last device should be connected to the WXI and RXI pins 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.
The CY7C42X5V provides five status pins. These pins are decoded to determine one of five states: Empty, Almost Empty, Half Full, Almost Full, and Full (see Table 2). The Half Full flag shares the WXO pin. This flag is valid in the stand-alone and width-expansion configurations. In the depth expansion, this pin provides the expansion out (WXO) information that is used to signal the next FIFO when it will be activated.
The Empty and Full flags of the CY7C42X5V are synchronous, i.e., they change state relative to either the Read Clock (RCLK) or the write clock (WCLK). When entering or exiting the Empty states, the flag is updated exclusively by the RCLK. The flag denoting Full states is updated exclusively by WCLK. The synchronous flag architecture guarantees that the flags will remain valid from one clock cycle to the next. As mentioned previously, the Almost Empty/Almost Full flags become synchronous if the VCC/SMODE is tied to VSS. All configurations are fabricated using an advanced 0.65 P-Well CMOS technology. Input ESD protection is greater than 2001V, and latch-up is prevented by the use of guard rings.
CY7C4235V Data Sheet
