STMicroelectronics LM239D

Overview

LM239D 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 LM239D datasheet, LM239D pinout, LM239D application, or LM239D equivalent, key selection considerations include input common-mode range extending to ground, rail-to-rail differential input capability, TTL/CMOS-compatible open-collector outputs, and thermal performance in SO14 (R_thJA = 105 °C/W).

Technical Context

The LM239D integrates four independent comparators with PNP-input stages, enabling input common-mode voltage down to ground on single supply - a critical feature for direct sensing of 0 V–referenced signals like battery voltage or transducer outputs. Its large-signal voltage gain exceeds 50 V/mV and response time is 1.3 μs (100 mV step, 5 mV overdrive) with 5.1 kΩ pull-up to V_CC.

Each comparator features open-collector output capable of sinking up to 16 mA, compatible with TTL, DTL, ECL, MOS, and CMOS logic families. Input offset voltage remains stable across temperature (±2 mV max for LM239A grade), and supply current stays constant at 1.1 mA typ regardless of V_CC from 5 V to 30 V.

Key Specifications

Pinout & Package

LM239D is supplied in SO14 (Small Outline, 14-pin) plastic micropackage per JEDEC MS-012, with 1.27 mm pitch, 8.55–8.75 mm body length, and R_thJA = 105 °C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM339DR and TLV331IPW, the LM239D uniquely balances industrial temperature range, wide-supply operation, and quad integration in one SO14 package - making it optimal for embedded control systems requiring reliability across harsh environments without redesign.

Availability

LM239D is available at Aetrix Electronics and suitable for industrial power supply monitoring, automotive battery management, factory automation sensor interfaces, and medical zero-crossing detection requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LM239D 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, specializing in automotive, industrial, and power management ICs with strong manufacturing and R&D infrastructure across Europe and Asia.

The LM239 series belongs to ST's precision analog comparators product line, engineered specifically for robust, low-cost threshold detection in harsh-environment applications where ground-referenced inputs and wide supply tolerance are mandatory.

FAQ

Can LM239D operate from a single 3.3 V supply?

Yes - LM239D supports single-supply operation from +2 V to +36 V. At 3.3 V, its input common-mode range is 0 V to 1.8 V, and output saturation voltage remains ≤400 mV at 4 mA sink current. Input offset voltage increases slightly (±2 mV max), but remains functional for most 3.3 V logic interfacing.

Does LM239D require external pull-up resistors on its outputs?

Yes - all four outputs are open-collector NPN transistors and must be pulled up to a valid logic HIGH voltage (e.g., V_CC, 3.3 V, or 5 V) via external resistors. Typical values range from 1.8 kΩ (for 5 mA sink) to 10 kΩ (for low-power applications); resistor value directly affects rise time and power consumption.

What is the maximum sink current per output of LM239D?

LM239D guarantees 6 mA minimum sink current per output at V_OL ≤ 400 mV (T_A = 25 °C). Absolute maximum rating allows ~20 mA continuous, but thermal limits (R_thJA = 105 °C/W) restrict sustained operation above 10 mA in still-air SO14 packages without derating.

How does LM239D handle input voltages exceeding the positive supply rail?

LM239D permits differential input voltage up to ±36 V and allows either input to exceed V_CC by up to 0.3 V without damage. However, the common-mode voltage must stay within 0 V to (V_CC − 1.5 V); exceeding this upper limit risks incorrect output states or latch-up if both inputs go significantly above V_CC.