Texas Instruments LM397MF

Overview

LM397MF from Texas Instruments is a single general-purpose voltage comparator with bipolar input stage, open-collector NPN output, and industrial temperature range (−40°C to +85°C). It operates from 5 V to 30 V single or dual supply, delivers 440 ns propagation delay at 50-mV overdrive, and features ±2 mV input offset voltage and 7 nA input bias current. It is used in A/D converter front-ends and pulse generators where rail-to-rail input common-mode (0 V to VS − 1.5 V) and logic-level interfacing via external pull-up are required.

For engineers reviewing the LM397MF datasheet, LM397MF pinout, LM397MF application, or LM397MF equivalent, key selection considerations include its SOT-23 (DBV) 5-pin package, open-collector output requiring external pull-up, −40°C to +85°C operating range, 300 µA typical supply current, and compatibility with TTL/CMOS logic translation through configurable output voltage levels.

Technical Context

The LM397MF implements a bipolar-input comparator architecture with input common-mode range extending to ground (0 V) and up to VS − 1.5 V at 25°C. Its open-collector output stage uses a grounded-emitter NPN transistor capable of sinking up to 13 mA, enabling wired-OR configurations and level-shifting by connecting the external pull-up resistor to any compatible logic rail (e.g., 3.3 V, 5 V, or 12 V).

It supports both single-supply (5 V to 30 V) and split-supply operation, with supply current virtually independent of supply voltage magnitude. Input offset voltage remains stable across temperature (±10 mV max over full range), and propagation delay improves with higher input overdrive-dropping from 940 ns (5 mV) to 440 ns (50 mV) for low-to-high transitions under 15 pF load.

Key Specifications

Pinout & Package

SOT-23 (DBV) 5-pin plastic package, 2.90 mm × 1.60 mm body size, 1.45 mm max height, JEDEC MO-178 compliant. Pin 1 marked with index area; pin 1 quadrant Q3 in tape-and-reel orientation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL331IDBVR, LM397MF offers identical performance and drop-in replacement capability; versus LMV331IDBVR, it trades ultra-low input bias for wide-voltage robustness and higher output drive-making LM397MF the preferred choice for industrial 5–30 V applications demanding ground-sensing and noise-immune operation.

Availability

LM397MF is available at Aetrix Electronics and suitable for industrial level monitoring, A/D converter triggering, pulse generation, and peak detection applications requiring stable component supply across extended temperature and voltage ranges.

Supply support for LM397MF 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 company headquartered in Dallas, Texas, delivering analog and embedded processing solutions for industrial, automotive, and personal electronics markets.

The LM397MF belongs to TI's general-purpose comparator product line, designed specifically for cost-sensitive industrial systems requiring reliable threshold detection, rail-to-ground input operation, and logic-level flexibility via open-collector outputs.

FAQ

What is the maximum supply voltage rating for the LM397MF?

The LM397MF has an absolute maximum supply voltage rating of 30 V, with recommended operating range specified from 5 V to 30 V. Operation beyond 30 V risks permanent damage per Absolute Maximum Ratings table in the SNOS977F datasheet. For long-term reliability in 24 V systems, derating to ≤28 V is advised under high-temperature conditions.

Does the LM397MF require an external pull-up resistor on its output?

Yes, the LM397MF features an open-collector NPN output stage and requires an external pull-up resistor connected between OUTPUT (Pin 4) and a positive voltage rail. The resistor value must balance speed (lower R) and power (higher R); typical values range from 1 kΩ to 10 kΩ depending on load capacitance and logic family requirements.

Can the LM397MF operate with a single 5-V supply and interface directly with 3.3-V logic?

Yes, the LM397MF can operate from a 5-V supply while interfacing with 3.3-V logic by connecting the external pull-up resistor to the 3.3-V rail instead of VS. This configuration ensures the high-state output voltage stays within 3.3-V logic high thresholds, and the open-collector architecture guarantees compatibility without level-shifting components.

What is the input common-mode voltage range of the LM397MF at 85°C?

At 85°C, the LM397MF input common-mode voltage range is specified as 0 V to VS − 2 V, per Electrical Characteristics table footnote (3) in SNOS977F. This is a degradation from the 0 V to VS − 1.5 V range at 25°C, meaning designers must ensure input signals remain ≥2 V below VS at maximum temperature to maintain valid comparison behavior.

Is the LM397MF pin-compatible with the TL331 comparator?

Yes, the LM397MF is explicitly documented as pin-compatible with TI's TL331 single differential comparator in the Device Information table and Description section of SNOS977F. Both share identical SOT-23 (DBV) 5-pin pinout, function mapping, and recommended operating conditions-enabling direct substitution in existing TL331 designs.