Texas Instruments LM361M/NOPB

Overview

LM361M/NOPB from Texas Instruments (formerly National Semiconductor) is a high-speed differential voltage comparator with complementary TTL outputs, 20 ns max propagation delay, ±15 V dual-supply operation, and 1 mV typical input offset voltage. It serves as a pin-for-pin replacement for SE529/NE529 in zero-crossing detection and flash analog-to-digital converter front-ends.

For engineers reviewing the LM361M/NOPB datasheet, LM361M/NOPB pinout, LM361M/NOPB application, or LM361M/NOPB equivalent, key selection criteria include guaranteed 20 ns max delay, tight output skew (≤5 ns), strobe-controlled output enable, ±6 V input common-mode range, and compatibility with op-amp supply rails.

Technical Context

The LM361M/NOPB implements a differential pair input stage with active load and emitter-follower outputs, optimized for minimal overdrive-dependent delay variation (±3 ns across 5–500 mV overdrive). Its strobe input enables synchronous output gating without external logic.

It operates with independent positive (V+), negative (V−), and TTL logic supply (VCC) rails-supporting ±15 V analog supplies while maintaining 4.75–5.25 V TTL-compatible output levels. Input resistance is 20 kΩ, and logical "1" output voltage is ≥2.4 V at −0.5 mA sink.

Key Specifications

Pinout & Package

Molded Dual-In-Line Package (DIP), 14-pin, NS Package Number M14A - through-hole mounting, JEDEC MS-001 compatible, 0.300" wide body.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-speed differential comparator applications.

Compared with LM361M/NOPB, LM360N reduces pin count but sacrifices built-in complementarity, while TL3016CD trades strobe functionality and tighter delay for broader supply flexibility and lower unit cost-neither is pin-compatible, requiring layout revision.

Availability

LM361M/NOPB is available at Aetrix Electronics and suitable for disk drive servo systems, flash analog-to-digital converters, high-frequency PWM controllers, and industrial threshold monitoring applications requiring stable component supply and long-term obsolescence management.

Supply support for LM361M/NOPB 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 acquired National Semiconductor in 2011 and maintains its precision analog portfolio, including legacy high-performance comparators and data converters.

The LM361M/NOPB belongs to National's high-speed comparator product line, designed specifically for timing-critical mixed-signal systems where deterministic propagation delay and output matching outweigh power efficiency concerns.

FAQ

What is the maximum operating temperature range for LM361M/NOPB?

The LM361M/NOPB is rated for 0°C to +70°C ambient operation, consistent with its commercial-grade LM361 designation. This differs from the military-grade LM161 (−55°C to +125°C) and industrial-grade LM261 (−25°C to +85°C). Thermal derating is not specified beyond this range, and operation outside 0°C–70°C may violate parametric guarantees in the datasheet. Always verify junction temperature under actual load conditions using the device's 600 mW power dissipation limit and package thermal resistance.

Does LM361M/NOPB require external compensation components?

No, the LM361M/NOPB includes internal frequency compensation and requires no external capacitors or resistors for stable operation. Pin 10 is labeled "Compensation" in the schematic but is an internal node with no user-accessible connection. The device is optimized for unity-gain stable operation across its full supply and temperature range, and adding external components may degrade propagation delay or increase overshoot.

Can LM361M/NOPB operate with a single +5 V supply?

No, the LM361M/NOPB requires three distinct supply connections: V+, V−, and VCC. It cannot function on a single +5 V rail. V+ and V− must be bipolar (e.g., +15 V and −15 V or +10 V and −10 V) to bias the differential input stage, while VCC must be 4.75–5.25 V for TTL output compliance. Attempting single-supply operation will result in undefined output states and potential damage if input voltages exceed absolute maximum ratings.

What is the purpose of the strobe input on LM361M/NOPB?

The strobe input on LM361M/NOPB is an active-low control that enables or disables both TTL outputs synchronously. When strobe is high, outputs reflect the differential input state; when strobe is low, both outputs are forced low regardless of input. This allows precise timing alignment in sampled-data systems-such as flash ADCs-where decisions must be gated by a system clock rather than occurring asynchronously. The strobe path has 8 ns delay, independently characterized in the datasheet.

Is LM361M/NOPB RoHS compliant and lead-free?

Yes, LM361M/NOPB carries the /NOPB suffix, which TI designates as "No Lead (Pb)-Free" and RoHS-compliant per EU Directive 2011/65/EU. The device uses matte tin lead finish and meets TI's Pb-Free Packaging Standard (SPRT00001). It is compatible with standard SnPb and lead-free reflow profiles, including peak temperatures up to 260°C for 10 seconds, as confirmed in the National Semiconductor soldering documentation.