SN74ALS870NT

Overview

The SN74ALS870NT is a dual 16-word by 4-bit register file in a 24-pin plastic DIP package. It operates on a supply voltage of 4.5 V to 5.5 V with an operating temperature range of 0°C to 70°C. The device features two independent register files, each with individual write-enable controls and address lines. It includes two 4-bit data I/O ports (DQA and DQB) with 3-state buffer-type outputs designed to drive bus lines directly.

Feature Summary

• Features two independent 16-word by 4-bit register files with individual write-enable controls and address lines for flexible memory management.
• Includes two 4-bit data I/O ports with 3-state buffer-type outputs capable of driving bus lines directly.
• Designed specifically for Multibus architecture and overlapping file operations with prioritized B-input port to prevent write conflicts during dual-input mode.

Applications

• Multibus architecture systems
• Overlapping file operations
• Dual-input mode applications

Procurement Notes

Verify the SN74ALS870NT datasheet SDAS139A for absolute maximum ratings and recommended operating conditions. Confirm the 24-pin PDIP NT package dimensions and pinout against your PCB layout. Ensure supply voltage stays within 4.5 V to 5.5 V and temperature range is 0°C to 70°C. Check for RoHS compliance status if required for your assembly process.

Selection Notes

Select this component when designing systems requiring dual independent 4-bit register files with direct bus driving capabilities. It is suitable for Multibus architectures where overlapping file operations are necessary. Consider the 3-state outputs for bus sharing and the prioritized B-input port for conflict prevention in dual-input scenarios.

Part Context

The SN74ALS870 belongs to the Texas Instruments ALS logic family, known for advanced low-power Schottky technology. This specific part integrates dual register files into a single 24-pin package, offering a compact solution for memory-intensive digital designs. It complements other ALS logic gates and flip-flops in system-level implementations.

Replacement Considerations

Check for SN74ALS870DW or SN74ALS870NSR equivalents if different packaging is needed. Verify functional compatibility with other dual register file components in the ALS series before substitution.

FAQ

What is the function of the S0 and S1 select lines?

The S0 and S1 select lines control which register file (1R or 2R) has access to the A and B ports, enabling flexible routing of data between the registers and I/O ports.

How does the device prevent write conflicts in dual-input mode?

The B-input port takes priority over the A-input port to prevent writing conflicts during dual-input mode operations.