SN74ACT3651-15PQ

Overview

The SN74ACT3651-15PQ is a high-speed, low-power CMOS clocked FIFO memory featuring a 2048 x 36 dual-port SRAM architecture. It supports independent asynchronous or coincident clocks for Port A and Port B, enabling data buffering between them. The device offers fast access times of 11 ns and supports clock frequencies up to 67 MHz. It includes retransmit capability, mailbox registers for control communication, and programmable almost-full and almost-empty flags synchronized to their respective port clocks.

Feature Summary

• Supports synchronous read-retransmit capability allowing repeated access to previously read data starting from a user-selected position.
• Features two 36-bit mailbox registers that pass command and control information between ports with dedicated status flags.
• Includes programmable almost-full and almost-empty flags synchronized to their respective port clocks to indicate memory fill levels.
• Provides pin-to-pin compatibility with SN74ACT3631 and SN74ACT3641 devices.

Applications

• Buffering data transfer between microprocessors and buses with synchronous control interfaces
• Programmable DSP-interface applications for FIR filtering
• Initializing DMA control using bypass registers

Procurement Notes

Verify the specific suffix '15PQ' against the manufacturer's current datasheet to confirm package type and speed grade. Ensure the component meets the required operating temperature range of 0°C to 70°C. Confirm availability as this part may be subject to production lifecycle changes.

Selection Notes

Select this component when a high-density 36-bit wide FIFO buffer is required for asynchronous or coincident clock domains. Consider its retransmit feature for applications needing data loopback. Verify interface compatibility with the target system's voltage levels and clock speeds up to 67 MHz.

Part Context

This device belongs to the SN74ACT series of advanced CMOS logic components manufactured by Texas Instruments. It is part of a family of clocked FIFO memories designed for high-speed data buffering in complex digital systems requiring reliable synchronization between different clock domains.

Replacement Considerations

SN74ACT3631-15PQ

FAQ

How are the almost-full and almost-empty flag offsets programmed?

The offset values can be loaded via three methods: automatically loading one of two preset values (8 or 64), parallel loading from Port A inputs, or serial loading through the FS0/SD and FS1/SEN pins during reset.

What is the function of the Retransmit Mode (RTM) input?

When RTM is high, the FIFO enters retransmit mode, allowing data to be read repeatedly starting from a selected word. This prevents ongoing writes from destroying the retransmit data until the mode is deactivated.