Texas Instruments LM361MX

Overview

LM361MX 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 converters.

For engineers reviewing the LM361MX datasheet, LM361MX pinout, LM361MX application, or LM361MX equivalent, key selection factors include guaranteed 20 ns max delay, tight output skew (≤5 ns), strobe-controlled output enable/disable, ±6 V input common-mode range, and compatibility with op-amp supply rails.

Technical Context

The LM361MX implements a bipolar differential pair front-end with active load and complementary TTL output stage, enabling fast response to small overdrives (3 ns delay variation across 5–500 mV). Its strobe input allows synchronous output gating without external logic.

It operates with independent V+, V−, and VCC supplies: V+ and V− set the analog input range (±6 V common-mode), while VCC powers the TTL outputs (4.75–5.25 V). Input bias current is 5–10 µA, and input resistance is 20 kΩ at 1 kHz.

Key Specifications

Pinout & Package

Molded Dual-In-Line Package (DIP), 14-pin, NS Package Number M14A. RoHS-compliant, through-hole mountable.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM361N and LM161H/883, the LM361MX offers identical speed and accuracy in the commercial-temperature M14A DIP package-optimized for cost-sensitive, volume production of disk drive electronics and data acquisition systems.

Availability

LM361MX is available at Aetrix Electronics and suitable for disk drive servo systems, flash ADC front-ends, and industrial motor control requiring stable component supply across multi-year production cycles.

Supply support for LM361MX 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 high-performance analog portfolio, including precision comparators, data converters, and interface ICs.

The LM361MX belongs to National Semiconductor's legacy high-speed comparator family, designed specifically for timing-critical signal conditioning in storage subsystems and real-time data acquisition.

FAQ

What is the maximum operating temperature range for the LM361MX?

The LM361MX is rated for 0°C to +70°C ambient operating temperature. This commercial-grade specification distinguishes it from the LM161 (−55°C to +125°C) and LM361H (−55°C to +125°C), making the LM361MX appropriate for office equipment, consumer storage devices, and non-military industrial applications where extended temperature performance is not required. All electrical characteristics in the datasheet are guaranteed within this range.

Does the LM361MX require external pull-up resistors on its TTL outputs?

No, the LM361MX does not require external pull-up resistors. Its outputs are fully buffered complementary TTL drivers capable of sourcing 0.5 mA and sinking 6.4 mA while maintaining valid logic levels. The LM361MX drives standard TTL loads directly, eliminating external components and reducing board space-critical in dense comparator arrays used in flash ADCs and disk drive read channels.

Can the LM361MX operate with a single +5 V supply?

No, the LM361MX cannot operate with a single +5 V supply. It requires three independent supply connections: V+ (positive analog rail), V− (negative analog rail), and VCC (TTL output rail). Minimum recommended analog supply is ±5 V; typical operation uses ±15 V for full common-mode range. Using only +5 V on V+ while leaving V− open or grounded violates absolute maximum ratings and will damage the device.

What is the function of the strobe input on the LM361MX?

The strobe input on the LM361MX is an active-low enable control that gates the comparator outputs. When strobe is high (≥2.0 V), outputs reflect the instantaneous differential input state. When strobe is low (≤0.8 V), both outputs are forced low regardless of input. This feature enables synchronous sampling in pipelined architectures-e.g., freezing comparator decisions during ADC conversion cycles-and reduces dynamic power consumption when idle.

Is the LM361MX pin-compatible with the SE529/NE529 comparator?

Yes, the LM361MX is explicitly specified as a pin-for-pin replacement for the SE529 and NE529 comparators. Pin assignments, supply connections, input/output functions, and package outline (M14A DIP) match identically. Engineers can substitute LM361MX into existing SE529/NE529 designs without PCB modification, gaining improved speed (20 ns vs. 25 ns typical), lower input offset (1–5 mV vs. 5–10 mV), and tighter delay matching.