SNJ54ABT7819GB

Overview

The SNJ54ABT7819GB is a high-speed, low-power BiCMOS bidirectional clocked FIFO memory device manufactured by Texas Instruments. It integrates two independent 512 × 18 dual-port SRAM FIFOs to buffer data in opposite directions. The component operates with a supply voltage range of 4.5 V to 5.5 V and supports a maximum clock frequency of 50 MHz. It features fast access times of 9 ns with a 50-pF load and simultaneous-switching data outputs. The device is housed in an 84-pin Ceramic Pin Grid Array (CPGA) package and is characterized for operation over the full military temperature range of –55°C to 125°C.

Feature Summary

• Integrates two independent 512 × 18 dual-port SRAM FIFOs for buffering data in opposite directions.
• Supports asynchronous or coincident free-running clocks for Port A and Port B.
• Features programmable almost-full/almost-empty flags with configurable depth offsets.
• Includes synchronized input-ready and output-ready flags for reliable control signals.

Applications

• Microprocessor interface control logic
• Bidirectional bus buffering between processors
• Synchronous data transfer systems requiring independent clock domains

Procurement Notes

Verify the specific ordering suffix GB corresponds to the 84-pin CPGA package configuration. Confirm that the device status is LIFEBUY, indicating it is discontinued but available for lifetime purchase. Ensure compatibility with MIL-PRF-38535 standards if required for the application environment. Check for RoHS compliance status as the product may not meet current environmental directives.

Selection Notes

Select this component when designing systems requiring high-speed bidirectional data buffering with independent clock domains. The 18-bit data width and 512-word depth per FIFO are suitable for moderate-capacity synchronization tasks. Consider the 84-pin CPGA package constraints for PCB layout and thermal management. Verify that the 4.5 V to 5.5 V supply voltage aligns with the system power architecture.

Part Context

The SNJ54ABT7819 belongs to the Widebus family of advanced BiCMOS logic devices from Texas Instruments. It is released as a DSCC Standard Microcircuit Drawing (SMD) part, specifically 5962-9470401QXA. This series is designed for high-performance applications requiring robust synchronous memory interfaces with flexible flag programming capabilities.

Replacement Considerations

Public confirmed substitute part numbers include 5962-9470401QXA and 5962-9470401QYA. These variants share the same functional specifications and are released under the DSCC SMD standard. Verify pinout and electrical characteristics match before substitution.

FAQ

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

The offsets are programmed by bringing the PENA or PENB signal low after a reset and before writing data. The binary value on the A0-A7 or B0-B7 pins is latched on the subsequent clock transition.

What is the relationship between the Port A and Port B clocks?

The continuous clocks CLKA and CLKB are independent of one another and can be either asynchronous or coincident, allowing for flexible synchronization across different system domains.

How does the device handle empty or full conditions?

Input-ready (IRA/IRB) and output-ready (ORA/ORB) flags are synchronized to their respective port clocks. When input-ready is low, writes are disabled; when output-ready is low, reads are disabled, ensuring reliable flow control.