Texas Instruments LM339AM

Overview

LM339AM from Texas Instruments is a quad open-collector voltage comparator IC designed for industrial and embedded signal conditioning. It features ±3 mV maximum input offset voltage, 0.8 mA supply current per comparator (independent of supply voltage), 25 nA input bias current, and operates from 2 V to 36 V single supply (or ±1 V to ±18 V dual supply). It enables ground-sensing analog threshold detection in battery-powered sensor interfaces.

For engineers reviewing the LM339AM datasheet, LM339AM pinout, LM339AM application, or LM339AM equivalent, key selection criteria include its rail-to-rail input common-mode range down to GND, TTL/CMOS-compatible open-collector outputs, low power consumption suitable for always-on monitoring circuits, and compatibility with wired-OR logic configurations.

Technical Context

The LM339AM integrates four independent high-gain comparators on a single monolithic die, each with PNP differential input stages enabling input voltages down to ground on single-supply operation. Its uncommitted NPN output transistors support open-collector wiring, allowing direct interface with TTL, DTL, ECL, MOS, and CMOS logic families without level-shifting.

Input common-mode voltage range extends from GND to V+ − 1.5 V at 25°C, and differential input voltage tolerance reaches ±36 V - exceeding supply rails without damage. Bias current remains stable across 2–36 V supply range, ensuring consistent performance in variable-voltage systems like automotive or industrial power rails.

Key Specifications

Pinout & Package

LM339AM is supplied in a 14-pin SOIC (Small Outline Integrated Circuit) package measuring 8.65 mm × 3.91 mm, optimized for surface-mount assembly and space-constrained PCB layouts.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad open-collector comparator applications.

Compared with LM339N and LM2901DT, the LM339AM delivers superior temperature stability and tighter offset voltage control, making it the preferred choice for industrial-grade analog thresholding where reliability across thermal extremes and precision are non-negotiable.

Availability

LM339AM is available at Aetrix Electronics and suitable for overvoltage protection circuits, temperature threshold monitors, wired-OR logic interfaces, and zero-crossing detectors requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LM339AM 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

Texas Instruments is a global semiconductor leader specializing in analog and embedded processing technologies, with decades of expertise in precision analog IC design and industrial-grade reliability validation.

The LM339AM belongs to TI's legacy LMx39-N quad comparator product line, engineered specifically for robust, low-power, ground-sensing voltage comparison in industrial automation, power management, and sensor interface applications.

FAQ

What is the operating temperature range of the LM339AM?

The LM339AM is specified for operation from −40°C to +85°C, qualifying it for industrial environments including factory automation, outdoor equipment, and automotive under-hood auxiliary systems. This extended range distinguishes it from the commercial-grade LM339N (0°C to +70°C) and ensures stable comparator performance across thermal cycling without calibration drift.

Can the LM339AM operate from a single 3.3 V supply?

Yes, the LM339AM supports single-supply operation from 2 V to 36 V, including 3.3 V. At 3.3 V, its input common-mode range extends from GND to 1.8 V, and output saturation voltage remains ≤250 mV at 4 mA sink - enabling direct interface with 3.3 V logic families when paired with appropriate pull-up resistors.

Does the LM339AM require external hysteresis for stable operation?

Hysteresis is recommended when input signals have slow edges or are susceptible to noise, as the LM339AM's high gain can cause oscillation during transitions. The datasheet advises adding 1–10 mV of positive feedback; this is not mandatory for clean, fast-rising signals like clock edges or digital pulses, but strongly advised for sensor inputs or slowly varying analog waveforms.

How does the open-collector output of the LM339AM interface with 5 V TTL logic?

The LM339AM's open-collector outputs interface directly with 5 V TTL by connecting a pull-up resistor (typically 4.7 kΩ) between the output pin and +5 V. When active, the output sinks current and pulls down to ≤250 mV - satisfying TTL LOW input requirement (<0.8 V). When inactive, the output floats, allowing the pull-up to assert TTL HIGH (>2.0 V).

Is the LM339AM pin-compatible with other LM339 variants like LM339N or LM2901?

Yes, the LM339AM shares identical 14-pin SOIC pinout and functional assignment with LM339N, LM2901, and LM239. All variants use the same pin configuration: outputs on pins 1, 2, 13, 14; inputs on pins 4–5, 6–7, 8–9, 10–11; V+ on pin 3; GND on pin 12. Mechanical and electrical compatibility enables drop-in replacement where temperature and offset specifications align.