The SN74ACT3632 is a high-speed, low-power CMOS clocked bidirectional FIFO memory. It supports clock frequencies up to 67 MHz and has read access times as fast as 11 ns. Two independent 512 × 36 dual-port SRAM FIFOs on the chip buffer data in opposite directions. Each FIFO has flags to indicate empty and full conditions and two programmable flags, almost full (AF\) and almost empty (AE\) to indicate when a selected number of words is stored in memory. Communication between each port can bypass the FIFOs via two 36-bit mailbox registers. Each mailbox register has a flag to signal when new mail has been stored. Two or more devices can be used in parallel to create wider datapaths.

The SN74ACT3632 is a clocked FIFO, which means each port employs a synchronous interface. All data transfers through a port are gated to the low-to-high transition of a port clock by enable signals. The clocks for each port are independent of one another and can be asynchronous or coincident. The enables for each port are arranged to provide a simple bidirectional interface between microprocessors and/or buses with synchronous control.

The input-ready (IRA, IRB) flag and almost-full (AFA\, AFB\) flag of a FIFO are two-stage synchronized to the port clock that writes data to its array. The output-ready (ORA, ORB) flag and almost-empty (AEA\, AEB\) flag of a FIFO are two-stage synchronized to the port clock that reads data from its array. Offset values for the AF\ and AE\ flags of both FIFOs can be programmed from port A.

The SN74ACT3632 is characterized for operation from 0°C to 70°C.

For more information on this device family, see the following application reports: FIFO Mailbox-Bypass Registers: Using Bypass Registers to Initialize DMA Control (literature number SCAA007) Interfacing TI Clocked FIFOs With TI Floating-Point Digital Signal Processors (literature number SCAA005) Metastability Performance of Clocked FIFOs (literature number SCZA004)

• Free-Running CLKA and CLKB Can Be Asynchronous or Coincident
• Two Independent 512 × 36 Clocked FIFOs Buffering Data in Opposite Directions
• Mailbox-Bypass Register for Each FIFO
• Programmable Almost-Full and Almost-Empty Flags
• Microprocessor Interface Control Logic
• IRA, ORA, AEA\, and AFA\ Flags Synchronized by CLKA
• IRB, ORB, AEB\, and AFB\ Flags Synchronized by CLKB
• Low-Power 0.8-um Advanced CMOS Technology
• Supports Clock Frequencies up to 67 MHz
• Fast Access Times of 11 ns
• Pin-to-Pin Compatible With the SN74ACT3622 and SN74ACT3642
• Package Options Include 120-Pin Thin Quad Flat (PCB) and 132-Pin Plastic Quad Flat (PQ) Packages