STMicroelectronics LM139N

Overview

LM139N from STMicroelectronics is a low-power quad voltage comparator designed for precision threshold detection in single-supply industrial and automotive systems. It operates from +2 V to +36 V (or ±1 V to ±18 V), features ±1 mV typical input offset voltage, 25 nA typical input bias current, and rail-to-rail input common-mode range including ground - enabling direct sensing of signals referenced to 0 V. It drives TTL/CMOS loads with 250 mV typical output saturation voltage at 4 mA sink current.

For engineers reviewing the LM139N datasheet, LM139N pinout, LM139N application, or LM139N equivalent, key selection criteria include input offset stability over temperature, single-supply ground-sensing capability, open-collector output compatibility with mixed-voltage logic families, and thermal performance in SO14 packaging under continuous 125 °C ambient operation.

Technical Context

The LM139N uses a PNP-input differential pair architecture that enables input common-mode voltage down to –0.3 V (relative to VCC–) and up to VCC+ – 1.5 V - critical for ground-referenced sensor interfacing. Its open-collector outputs support wired-OR logic and level translation across 3.3 V, 5 V, and 15 V domains without external pull-ups on the comparator side.

It delivers 1.3 μs typical response time for 100 mV input steps with 5 mV overdrive, and maintains <2.5 mA total supply current across full 2–36 V supply range - making it suitable for battery-backed monitoring and low-quiescent power supervisory circuits where supply headroom is constrained.

Key Specifications

Pinout & Package

LM139N is supplied in the 14-pin plastic small-outline (SO14) package per JEDEC MS-012, with 1.27 mm pitch, gull-wing leads, and 8.65 mm × 3.9 mm body dimensions. Thermal pad is not present; mounting requires standard reflow profile for plastic packages.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad voltage comparator applications.

Compared with LM339N, LM139N adds –55 °C to +125 °C qualification and tighter offset drift control; compared with TLV339IPW, it trades nanowatt quiescent power for robustness across 2–36 V and extreme temperature ranges - making it the sole choice for under-hood or factory-floor deployment.

Availability

LM139N is available at Aetrix Electronics and suitable for industrial motor control, automotive body electronics, and programmable logic controller (PLC) I/O modules requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LM139N includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing analog, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

The LM139 series belongs to ST's precision analog comparators product line, engineered specifically for high-reliability threshold detection in harsh environments where supply voltage variation, temperature extremes, and ground-referenced sensing are dominant design constraints.

FAQ

Can LM139N operate from a single 3.3 V supply?

Yes. The LM139N functions with VCC+ as low as +2 V, so 3.3 V is fully supported. However, its input common-mode range extends only to VCC+ – 1.5 V (i.e., up to 1.8 V), and output saturation voltage remains ~250 mV at 4 mA - meaning logic-high levels must be pulled up externally to 3.3 V, not generated internally.

Does LM139N require external pull-up resistors on its outputs?

Yes. All four outputs are open-collector NPN transistors and cannot source current. A pull-up resistor to a defined logic rail (e.g., 3.3 V, 5 V, or 15 V) is mandatory for functional high-state output. Typical values range from 2.2 kΩ (for fast edges) to 10 kΩ (for low power), depending on load capacitance and speed requirements.

What is the maximum safe input voltage if VCC+ = 0 V?

Per Absolute Maximum Ratings, VIN must stay between –0.3 V and +36 V regardless of VCC state. With VCC+ = 0 V (i.e., unpowered), applying any voltage > –0.3 V to an input risks forward-biasing ESD protection diodes and causing latch-up or damage. Inputs must be held ≤ –0.3 V or disconnected during power-off conditions.

How does LM139N differ from LM339N in layout compatibility?

LM139N and LM339N share identical SO14 footprint, pinout, and solder profile - they are drop-in replacements on PCBs. The sole difference is temperature grade: LM139N is rated for –55 °C to +125 °C, while LM339N is limited to 0 °C to +70 °C. No layout or schematic changes are needed for substitution.