Texas Instruments LM361H

Overview

LM361H from Texas Instruments (formerly National Semiconductor) is a high-speed differential 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 LM361H datasheet, LM361H pinout, LM361H application, or LM361H equivalent, key selection considerations include strobe-controlled output enable, tight 5 ns max output skew, ±6 V input common-mode range, and operation across 0°C to +70°C commercial temperature range.

Technical Context

The LM361H implements a differential input stage with independent strobe control enabling output gating without affecting internal comparator dynamics. Its complementary TTL outputs are actively driven-logical "1" at ≥2.4 V (I_SOURCE = −0.5 mA), logical "0" at ≤0.4 V (I_SINK = 6.4 mA)-and exhibit matched propagation delays (tpd(0)/tpd(1) ≤20 ns, skew ≤5 ns).

It operates from split supplies (V+ = +5 to +15 V, V− = −6 to −15 V) and a separate TTL logic supply (V_CC = 4.75–5.25 V), isolating analog signal path from digital interface. Input resistance is 20 kΩ, and ESD tolerance is 1600 V (HBM).

Key Specifications

Pinout & Package

Metal Can Package (NS H10C), hermetically sealed, 10-pin round can with bottom view pin 1 identifier. Designed for high-reliability, low-noise environments including test equipment and aerospace-qualified subsystems.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM361N and TL3016CD, the LM361H uniquely combines hermetic metal-can packaging, ±15 V dual analog supply support, active strobe control, and guaranteed 20 ns timing-all within commercial temperature grade-making it optimal for legacy test equipment upgrades and EMI-sensitive instrumentation.

Availability

LM361H is available at Aetrix Electronics and suitable for disk drive servo systems, flash ADC front-ends, high-speed pulse discriminators, and industrial overvoltage protection circuits requiring stable component supply and long-term obsolescence management.

Supply support for LM361H 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, emphasizing high-reliability signal conditioning and interface ICs for industrial, automotive, and test equipment markets.

The LM361H belongs to National Semiconductor's legacy high-speed comparator family, engineered specifically for timing-critical analog-digital boundary applications where propagation delay consistency, output skew, and supply flexibility are design-critical.

FAQ

What is the maximum propagation delay specification for LM361H?

The LM361H has a maximum propagation delay of 20 ns for both tpd(0) and tpd(1) under standard operating conditions (V+ = +10 V, V− = −10 V, V_CC = +5 V, T_A = 25°C). This value is guaranteed across the full 0°C to +70°C operating range and applies to both true and complementary outputs, making LM361H suitable for sub-50-ns timing windows in flash ADCs and servo loop feedback paths.

Does LM361H support single-supply operation?

No, LM361H requires dual analog supplies (V+ and V−) plus a separate TTL logic supply (V_CC). The datasheet specifies V+ = +5 to +15 V, V− = −6 to −15 V, and V_CC = 4.75–5.25 V. It cannot operate from a single-ended supply such as +5 V only. Attempting single-supply use will result in undefined output behavior and potential damage if absolute maximum ratings are exceeded. LM361H is designed explicitly for bipolar signal conditioning environments.

What is the function of the Strobe pin on LM361H?

The Strobe pin (Pin 4) is an active-low output enable control. When pulled below 0.8 V, it forces both Output A (Q) and Output B (Q̅) to logic low regardless of input state, drawing −1.6 mA. When high (>2.0 V), outputs respond normally to differential input. This feature allows synchronous blanking in multi-comparator systems-critical in flash ADCs and time-interleaved architectures-without adding external gating logic. Strobe delay is specified at 8 ns.

Is LM361H pin-compatible with SE529 or NE529?

Yes, LM361H is explicitly documented as a pin-for-pin replacement for SE529 and NE529. All 10 pins-including V+, V−, V_CC, strobe, inputs, outputs, ground, and case-map identically between LM361H and those legacy devices. Electrical improvements include lower input offset voltage (1–5 mV vs. up to 10 mV), tighter delay matching (≤5 ns skew vs. unspecified), and guaranteed 20 ns max propagation-making LM361H a direct drop-in upgrade where enhanced speed and accuracy are needed.

What package type does LM361H use, and what are its key mechanical features?

LM361H uses the NS H10C metal can package: a hermetically sealed, 10-pin circular can with bottom-view pin 1 indicator. Its case is internally tied to Pin 5 (Ground), providing inherent EMI shielding and thermal conduction to chassis. Unlike plastic DIP variants (e.g., LM361N), the H10C construction meets MIL-STD-883 requirements for humidity resistance and mechanical robustness-ideal for avionics, test equipment, and mission-critical industrial systems where long-term reliability under thermal cycling is essential.