LM139FK

Overview

The LM139FK is a quad differential comparator from the LM139-MIL family, characterized for operation over the full military temperature range of –55°C to +125°C. It operates from single supplies of 2 V to 36 V or dual supplies of ±1 V to ±18 V. Key electrical specifications include a typical supply current of 0.8 mA, input bias current of 25 nA, and input offset voltage of 2 mV at 25°C. The device features open-collector outputs compatible with TTL, MOS, and CMOS logic levels.

Feature Summary

• Four independent precision-voltage comparators designed for wide single or dual supply operation
• Input common-mode voltage range includes ground potential
• Differential input voltage range matches the maximum-rated supply voltage
• Open-collector outputs allow wired-AND functionality and flexible logic level translation

Applications

• Industrial control systems
• Automotive infotainment and instrument clusters
• Body control modules
• Power supervision circuits
• Oscillators and peak detectors

Procurement Notes

Verify that the specific orderable part number corresponds to the LCCC (FK) package variant. Confirm compliance requirements against MIL-PRF-38535 if space-grade qualification is necessary, as standard production processing may not test all parameters. Ensure the design accounts for the hermetically sealed ceramic construction suitable for harsh environments.

Selection Notes

Select this component when military-grade temperature stability (-55°C to +125°C) and high reliability are required. The FK package provides a 20-pin leadless ceramic chip carrier option for applications needing robust physical protection. Consider the low input bias current and wide common-mode range for high-impedance sensor interfaces.

Part Context

The LM139FK belongs to the LM139-MIL series, which consists of four independent voltage comparators. Unlike standard commercial variants, this family is characterized for the full military temperature range. The device utilizes a PNP Darlington pair input stage for high gain and fast response with minimal input bias current.

Replacement Considerations

LM139-SP

FAQ

What is the input common-mode voltage range?

The common-mode input voltage range includes ground and extends up to VCC minus 1.5 V at 25°C, or VCC minus 2 V across the full operating temperature range.

How does the output configuration work?

The outputs are open-collector NPN transistors. They sink current when the negative input is higher than the positive input and require an external pull-up resistor to define the high logic level.