STMicroelectronics LM211N

Overview

LM211N from STMicroelectronics is a bipolar voltage comparator with strobe functionality, designed for precision threshold detection in industrial control and power management circuits. It features ±30 V differential input voltage range, 150 nA maximum input current, 50 mA output sink capability, and operates from +5 V to ±15 V supply rails. Used in overvoltage protection circuits where high-voltage tolerance and TTL/RTL-compatible open-collector output are required.

For engineers reviewing the LM211N datasheet, LM211N pinout, LM211N application, or LM211N equivalent, key selection criteria include input offset voltage (≤4 mV), strobe-enabled disable control, wide common-mode range (−14.5 V to +13.8 V), and SO-8 package thermal performance (R_thJA = 175 °C/W).

Technical Context

The LM211N implements a dual-transistor differential input stage with active load, enabling low input bias current (≤150 nA) and stable operation across −40 °C to +105 °C. Its open-collector NPN output supports up to +50 V external pull-up and 50 mA sink current, allowing direct interface with relay drivers and logic families without level-shifting.

Strobe functionality provides active-low enable/disable control of the output stage, reducing quiescent current during idle periods. The device does not include internal hysteresis, requiring external feedback for noise-immune switching in noisy environments.

Key Specifications

Pinout & Package

LM211N is housed in an SO-8 plastic micropackage (ECOPACK® compliant), with standard 1.27 mm pitch, 5.0 mm × 4.0 mm body, and 1.65 mm max height. Thermal resistance R_thJA = 175 °C/W enables operation up to +105 °C ambient with appropriate PCB copper area.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM311DR and TL311CP, the LM211N uniquely combines extended temperature rating (−40 °C to +105 °C), strobe control, and ±30 V input range-making it the only option for ruggedized industrial sensing where timing-gated comparison and wide supply flexibility are mandatory.

Availability

LM211N is available at Aetrix Electronics and suitable for overvoltage protection circuits, battery charge termination systems, and industrial relay driver interfaces requiring stable component supply across automotive-qualified temperature ranges and long-lifecycle production programs.

Supply support for LM211N 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 LM211N belongs to ST's precision analog comparator product line, engineered specifically for robust threshold detection in harsh environments where wide supply range, high-voltage tolerance, and temperature stability are critical.

FAQ

Does the LM211N require external hysteresis for noise immunity?

Yes. The LM211N has no internal hysteresis. In electrically noisy environments-such as motor drive feedback or AC line sensing-external positive feedback (e.g., resistor from output to non-inverting input) must be added to prevent multiple output transitions near the threshold. Typical hysteresis values range from 10 mV to 100 mV depending on signal slew rate and noise amplitude.

Can the LM211N operate from a single +5 V supply?

Yes. The LM211N is fully specified for +5 V single-supply operation, with input common-mode range extending from −0.3 V to +3.7 V and output capable of sinking current to within 0.75 V of V− (ground). This enables direct interface with 5 V microcontrollers and logic without level shifters or negative rails.

What is the function of Pins 5 and 8 (Offset Null)?

Pins 5 and 8 form a two-terminal offset null network. A 10 kΩ potentiometer is connected between them, with its wiper tied to V−. Adjusting the potentiometer balances the input stage, reducing input offset voltage to <1 mV. This calibration is essential in precision applications like battery voltage monitoring where ±5 mV error is unacceptable.

How does the Strobe pin affect output behavior?

When Strobe (Pin 3) is pulled low (≤0.8 V), the output transistor is turned off, placing the Output (Pin 6) in high-impedance state regardless of input conditions. When Strobe is high (≥2.0 V), normal comparator operation resumes. This allows time-synchronized sampling, power gating, or multiplexed sensor reading without adding external switches or logic gates.