STMicroelectronics LM139DT

Overview

LM139DT from STMicroelectronics is a low-power quad voltage comparator in SO14 package, designed for single-supply operation from +2 V to +36 V (or ±1 V to ±18 V dual supply), with ±1 mV typical input offset voltage, 25 nA typical input bias current, and 250 mV typical low-level output saturation voltage at 4 mA sink current. It enables precision threshold detection in industrial control, power supply monitoring, and sensor interface circuits where ground-referenced inputs are required.

For engineers reviewing the LM139DT datasheet, LM139DT pinout, LM139DT application, or LM139DT equivalent, key selection criteria include input common-mode range extending to ground on single supply, rail-to-rail differential input capability, TTL/CMOS-compatible open-collector outputs, and guaranteed operation over –55 °C to +125 °C.

Technical Context

The LM139DT integrates four independent comparators with PNP-input stages, enabling input common-mode voltage down to ground even under single-supply operation. Its differential input voltage range equals the full supply voltage (±36 V max), and output stage is an open-collector NPN transistor capable of sinking up to 16 mA.

It features low supply current (1.1 mA typ. at 5 V, independent of supply voltage), low input offset current (±5 nA typ.), and fast response time (1.3 μs typ. at 100 mV step with 5 mV overdrive). The device lacks internal compensation and requires no external components for stable comparator operation.

Key Specifications

Pinout & Package

LM139DT is housed in a 14-pin SOIC (SO14) plastic micropackage per JEDEC MS-012, with 1.27 mm pitch, 8.75 mm body length, and 4.0 mm body width. Thermal resistance junction-to-ambient is 105 °C/W (SO14).

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM339DT and TL331IDBVR, the LM139DT uniquely delivers military-grade temperature range (–55 °C to +125 °C), guaranteed ground-sensing capability on single supply, and quad integration in SO14 - making it the only drop-in solution for high-reliability industrial monitoring where thermal stability and input flexibility are mandatory.

Availability

LM139DT is available at Aetrix Electronics and suitable for industrial power supply monitors, automotive battery supervisors, sensor threshold detectors, and zero-crossing detectors requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LM139DT 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-accuracy, wide-supply, single-rail sensing in harsh-environment applications such as factory automation, motor control, and power conversion systems.

FAQ

Can LM139DT operate from a 3.3 V supply?

Yes, LM139DT is specified to operate from +2 V to +36 V single supply. At 3.3 V, it maintains full functionality including ground-sensing input range (0 V to 1.8 V), 250 mV typical output saturation voltage, and 1.1 mA supply current. Output high level will be pulled up externally to 3.3 V, enabling direct interfacing with 3.3 V logic families.

Does LM139DT require external pull-up resistors on its outputs?

Yes - all four outputs are open-collector NPN transistors and must be pulled up to a voltage rail (which may differ from VCC+) via external resistors. Typical values range from 1 kΩ (for fast switching into heavy loads) to 100 kΩ (for low-power monitoring). No internal pull-ups exist; omission results in undefined high-state logic levels.

What is the maximum sink current per output of LM139DT?

LM139DT guarantees minimum sink current of 6 mA per output at VO = 1.5 V (per datasheet Table 3). Absolute maximum ratings allow short-term operation up to ~20 mA, but sustained current above 16 mA risks exceeding thermal limits in SO14 package due to R_θJA = 105 °C/W. Derating is required above 25 °C ambient.

How does LM139DT handle input voltages exceeding the positive supply rail?

LM139DT permits positive input excursions up to +36 V regardless of VCC+ level, provided the other input remains within the common-mode range (0 V to VCC+ − 1.5 V). This is enabled by its PNP input stage and absolute maximum rating of ±36 V differential input voltage - allowing direct connection to unregulated transducer outputs or fault-condition signals without external clamping.