Texas Instruments LM361N

Overview

LM361N from Texas Instruments is a high-speed differential comparator with complementary TTL outputs, ±15V dual-supply operation, 20 ns max propagation delay, and independent strobe control-designed for zero-crossing detection in disk file systems and high-speed analog-to-digital conversion interfaces.

For engineers reviewing the LM361N datasheet, LM361N pinout, LM361N application, or LM361N equivalent, this device requires attention to strobe logic polarity, input common-mode range (±6V), output skew tolerance (≤5 ns), and its PDIP-14 package thermal limits in industrial timing circuits.

Technical Context

The LM361N implements a fully differential input stage with low input offset voltage (1–5 mV) and tight delay matching between complementary outputs (≤5 ns skew). It uses bipolar transistor architecture optimized for speed over precision, with strobe-enabled output gating that disables both outputs when the strobe pin is low.

Its dual supply (±15V) supports wide analog input swing, while the separate VCC (4.75–5.25V) powers TTL-compatible outputs. Propagation delay remains stable across overdrive levels (5–500 mV), varying only ±3 ns-enabling reliable timing in fast edge-detection systems.

Key Specifications

Pinout & Package

LM361N is housed in a 14-pin plastic dual in-line package (PDIP), designated NFF0014A per TI documentation. The package features 0.3-inch body width, 0.1-inch lead pitch, and through-hole mounting compatibility.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM361M/NOPB and LM161H/NOPB, the LM361N offers through-hole assembly compatibility and commercial-temperature qualification-making it optimal for lab validation, legacy system upgrades, and low-volume industrial instrumentation where soldering flexibility and cost matter more than extended temperature or SMT scalability.

Availability

LM361N is available at Aetrix Electronics and suitable for hard disk drive servo systems, laser printer motor control, flash ADC front-ends, and industrial PWM monitoring requiring stable component supply and long-term obsolescence management.

Supply support for LM361N 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 leader founded in 1930, specializing in analog, embedded processing, and high-performance analog ICs for industrial, automotive, and communications markets.

The LM361N belongs to TI's legacy high-speed comparator product line, engineered specifically for precision timing-critical applications like disk drive read channel interfaces and real-time motor control feedback loops.

FAQ

What is the maximum allowable supply voltage for LM361N?

The LM361N supports V+ up to +16 V and V− down to −16 V as absolute maximum ratings, but operational specifications require V+ between +5 V and +15 V and V− between −6 V and −15 V. Exceeding these ranges risks parametric shift or permanent damage. Always refer to the LM361N datasheet Section 6.1 for derating curves and thermal limits.

Does LM361N support single-supply operation?

No, LM361N does not support true single-supply operation. Its input common-mode range is centered around mid-rail and requires dual supplies (e.g., ±12 V or +15 V/−15 V) to achieve full ±6 V input swing. Attempting single-supply use (e.g., 0 V and +15 V) violates the ±6 V common-mode specification and degrades delay matching and offset performance.

How does the strobe function work on LM361N?

The LM361N strobe pin (Pin 3) is active-low: when pulled ≤0.8 V (with VCC = 4.75 V), both outputs enter high-impedance state regardless of input differential voltage. When strobe ≥2.0 V, outputs respond normally. This enables synchronous sampling-critical in multi-channel ADCs where all comparators must latch simultaneously.

Can LM361N replace NE529 in existing designs?

Yes, LM361N is explicitly documented as a pin-for-pin replacement for NE529/SE529 with improved speed (20 ns vs. 25 ns typical) and lower input offset (1–5 mV vs. 5–10 mV). No PCB changes are required, but verify strobe logic compatibility and confirm VCC decoupling meets LM361N's tighter noise immunity requirements.

What is the purpose of Pins 11 and 12 on LM361N?

Pins 11 and 12 are offset null terminals. They connect to opposite ends of an external 10 kΩ potentiometer (wiper to V−) to adjust input offset voltage below 1 mV. This feature is rarely needed in standard applications but critical in precision zero-crossing detection where sub-millivolt errors affect timing jitter.