SN54LS21J

Overview

The SN54LS21J is a dual 4-input positive-AND gate manufactured by Texas Instruments. It operates within a supply voltage range of 4.75 V to 5.25 V and supports an operating temperature range of -55 °C to 125 °C. The device utilizes a 14-pin Ceramic Dual In-Line Package (CDIP). Key electrical characteristics include a maximum input clamp current of ±18 mA, a maximum output clamp current of ±20 mA, and a maximum low-level output current of 8 mA.

Feature Summary

• Contains two independent four-input AND logic gates
• Features hermetically sealed ceramic packaging for environmental protection
• Supports extended industrial and military temperature ranges

Applications

• Military avionics systems requiring radiation-hardened or high-reliability logic
• Defense communication equipment operating in extreme environments
• Spacecraft control units demanding long-term stability

Procurement Notes

Verify the specific ordering suffix against the manufacturer's package option addendum to confirm pin count and physical dimensions. Ensure the component meets QML certification requirements if intended for defense applications. Confirm RoHS status and lead finish specifications prior to integration into the bill of materials.

Selection Notes

Select this component when designing circuits that require isolated dual four-input AND functionality with high noise immunity. The LS series offers standard TTL compatibility while maintaining lower power consumption compared to earlier standards. Verify that the system voltage remains strictly within the specified 4.75 V to 5.25 V range to ensure reliable operation.

Part Context

This part belongs to the SN54xx family, which denotes military-grade performance and extended temperature capabilities compared to the commercial SN74xx series. The 'LS' designation indicates Low-power Schottky technology, providing a balance between speed and power dissipation. The 'J' suffix specifically identifies the 14-pin ceramic dual in-line package construction.

Replacement Considerations

Direct replacements include SNJ54LS21W and SNJ54LS21FK, which share identical logical functions but differ in package type. Cross-vendor equivalents from manufacturers such as Motorola or ON Semiconductor may be considered if they meet the same LS-TTL electrical specifications and MIL-STD mechanical constraints.