SN74ALS870DWR

Overview

The SN74ALS870DWR is a dual 16-by-4 register file manufactured by Texas Instruments in the ALS logic series. It features two independent 16-word by 4-bit memory arrays with individual write-enable controls and address lines. The device includes two 4-bit data I/O ports (DQA and DQB) with 3-state buffer-type outputs designed to drive bus lines directly. It operates within a supply voltage range of 4.5 V to 5.5 V and supports an operating temperature range from 0°C to 70°C.

Feature Summary

• Features two independent 16-word by 4-bit register files with dedicated write-enable controls and address decoding.
• Includes two 4-bit bidirectional data I/O ports with 3-state outputs for direct bus line driving.
• Designed specifically for multibus architecture and overlapping file operations.
• Prioritized B-input port prevents write conflicts during dual-input mode.

Applications

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

Procurement Notes

Verify the specific package variant, as the SN74ALS870 family includes SOIC (DW), NSOP (NS), and PDIP (NT) options. Confirm RoHS compliance status and lead finish details via the manufacturer's ordering information. Ensure the selected part number matches the required tape-and-reel or tube packaging format for your assembly process.

Selection Notes

Select this component when designing systems requiring dual independent register files with high-speed bus interfacing capabilities. The ALS series offers a balance of speed and power consumption suitable for standard TTL environments. Consider the prioritized B-input feature if simultaneous access to both register files is required without write conflicts.

Part Context

This device belongs to the SN74ALS870 family of dual 16-by-4 register files. It is characterized for commercial operation temperatures and is available in multiple package styles including plastic small-outline and standard plastic DIPs. The product is listed as active for new designs.

Replacement Considerations

SN74ALS870DW

FAQ

How does the device handle 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.

What is the function of the S2 and S3 select lines?

S2 determines whether the A ports are in input or output modes, while S3 performs the same function for the B ports.