Texas Instruments LM239N

Overview

LM239N from STMicroelectronics is a low-power quad voltage comparator IC designed for single-supply operation (2–36 V) or dual supplies (±1 V to ±18 V), featuring 1.1 mA typical supply current, ±1 mV typical input offset voltage, 25 nA typical input bias current, and rail-to-rail input common-mode range including ground. It drives TTL, CMOS, and ECL loads in industrial sensor interfaces and power monitoring circuits.

For engineers reviewing the LM239N datasheet, LM239N pinout, LM239N application, or LM239N equivalent, key selection criteria include input offset voltage stability over temperature, output sink capability (6–16 mA), common-mode range down to ground on single supply, and SO14 package thermal resistance (105 °C/W).

Technical Context

The LM239N integrates four independent comparators with PNP-input stages enabling input voltages down to −0.3 V below ground while maintaining functionality up to V_CC − 1.5 V. Its open-collector outputs support wired-OR logic and level translation across logic families.

It operates across −40 °C to +105 °C, with differential input voltage tolerance equal to full supply range (±36 V), and exhibits 1.3 μs typical response time at 100 mV overdrive - optimized for slow-to-moderate speed threshold detection rather than high-frequency signal comparison.

Key Specifications

Pinout & Package

LM239N is supplied in the 14-pin plastic small outline (SO14) package per JEDEC MS-012, with 1.27 mm pitch, 8.75 mm body length, and 4.0 mm body width. Thermal resistance is 105 °C/W (junction-to-ambient).

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM239N, LM339N trades extended temperature capability for lower cost in benign environments, while TLV339IPW offers superior power efficiency and speed but lacks voltage range, integration, and ruggedness for industrial 24 V monitoring.

Availability

LM239N is available at Aetrix Electronics and suitable for industrial power monitoring, automotive battery supervision, sensor signal conditioning, and zero-crossing detection requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LM239N 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, delivering intelligent power, sensing, and control solutions for industrial, automotive, and consumer markets.

The LM239N belongs to ST's legacy precision analog comparator family, engineered for robust performance in harsh industrial environments where reliability, wide supply range, and ground-sensing capability are essential.

FAQ

Can LM239N operate from a single 3.3 V supply?

Yes - the LM239N 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 0 V to 1.8 V, and output saturation voltage remains ≤400 mV at 4 mA sink current, enabling reliable interfacing with 3.3 V logic families using appropriate pull-up resistors.

Does LM239N require external pull-up resistors on its outputs?

Yes - all four outputs are open-collector and must be pulled up to a voltage rail (e.g., V_CC, 3.3 V, or 5 V) via external resistors. Typical values range from 1.8 kΩ (for 5 V TTL) to 10 kΩ (for low-power CMOS), selected based on sink current requirements and rise time constraints.

What is the maximum input voltage allowed when using LM239N on a 24 V single supply?

Either input may safely reach up to +30 V regardless of supply voltage, per absolute maximum rating VID = ±36 V and note that "positive excursions of input voltage may exceed the power supply level." However, the common-mode range is limited to 0 V to V_CC − 1.5 V (i.e., 0–22.5 V at 24 V), so valid comparison occurs only within that band unless used in overvoltage clamp configurations.

How does LM239N handle input signals below ground?

The LM239N permits input voltages down to −0.3 V relative to GND (V_CC−) without damage or phase reversal. This allows safe interfacing with slightly negative transients from inductive sensors or mismatched grounds, but sustained operation below −0.3 V risks increased input bias current and potential latch-up.