Texas Instruments LM134H

Overview

LM134H from Texas Instruments is a 3-terminal adjustable current source designed for precision biasing, temperature sensing, and low-power reference applications. It delivers programmable current from 1 μA to 10 mA with ±3% initial accuracy, operates over −55°C to +125°C, and maintains 0.02%/V current regulation across a 1 V to 40 V supply range. Its true 2-terminal operation enables use in remote sensor circuits where lead resistance must not affect accuracy.

For engineers reviewing the LM134H datasheet, LM134H pinout, LM134H application, or LM134H equivalent, key selection criteria include its wide dynamic voltage range, temperature-proportional output (≈+0.33%/°C), minimal sense voltage (64 mV at 25°C), compatibility with TO-metal-can packaging, and suitability for zero-drift current source design using external diode compensation.

Technical Context

The LM134H functions as a floating two-terminal current source whose output current is set by an external resistor connected between the SET and V− terminals. Its internal circuitry uses a temperature-dependent reference (64 mV at 25°C, proportional to absolute temperature) to establish I_SET = 67.7 mV / R_SET at 25°C, with inherent +0.336%/°C drift.

It achieves true 2-terminal operation without separate power rails, draws only microamperes under reverse bias up to 20 V, and exhibits 15 pF shunt capacitance. Thermal effects dominate regulation error above 100 μA due to junction self-heating (≈0.4°C per volt at 1 mA), requiring thermal management in high-accuracy DC applications.

Key Specifications

Pinout & Package

LM134H is housed in a hermetically sealed TO metal-can package (Package Number NDV), featuring three leads in bottom-view orientation: Pin 1 (V+), Pin 2 (V−), Pin 3 (SET). The package provides robust thermal performance (θ_jc = 32°C/W) and high-reliability operation in harsh environments.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar adjustable current source applications.

Compared with LM334Z/NOPB, LM134H offers superior temperature range and hermetic reliability; compared with LT3092IMS8E#PBF, it provides simpler 2-terminal integration at the expense of absolute accuracy and current headroom-making LM134H optimal for ruggedized, low-component-count current-source designs.

Availability

LM134H is available at Aetrix Electronics and suitable for remote temperature sensing, micropower biasing, and low-voltage reference generation requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for LM134H 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 specializing in analog and embedded processing technologies, with decades of heritage in precision linear ICs and industrial-grade components.

The LM134H belongs to TI's legacy precision current source family, engineered specifically for high-reliability temperature sensing, bias stabilization, and 2-wire transducer interfaces in aerospace, defense, and critical industrial systems.

FAQ

What is the correct pinout for LM134H in the TO metal-can package?

The LM134H uses a TO-NDV metal-can package with bottom-view pinout: Pin 1 is V+, Pin 2 is V−, and Pin 3 is SET. This configuration is confirmed in TI's official package drawing NDV and matches the connection diagram in SNVS746E Rev E. Incorrect orientation causes reverse-bias operation or failure to regulate.

Can LM134H operate below 1V supply voltage?

No-LM134H has a minimum operating voltage of 1V across V+ and V−, verified in Electrical Characteristics tables for all current ranges. At 10 μA, the minimum voltage drops to 0.8V, but TI specifies 1V as the guaranteed functional limit. Operation below 1V risks loss of regulation and unpredictable current output.

How does temperature affect LM134H output current, and can it be canceled?

LM134H output current increases ≈+0.336%/°C with junction temperature, directly proportional to absolute temperature (I_SET ∝ T(K)). This behavior is intrinsic and usable for temperature sensing. For zero-drift applications, TI's Figure 15 shows a diode + resistor network that cancels the tempco-achieving <±1% residual slope error after gain trim.

Is LM134H RoHS-compliant, and what is its lead finish?

LM134H/NOPB is RoHS-compliant (Pb-free), as indicated in TI's Package Option Addendum. The lead finish is specified as "Call TI" in official documentation, meaning TI manages plating per internal process controls; actual finish is matte tin over nickel, consistent with TI's standard NOPB qualification for TO packages.

What is the maximum power dissipation for LM134H, and how is it limited?

LM134H has an absolute maximum power dissipation of 400 mW, constrained by its TO-NDV package thermal resistance (θ_ja = 440°C/W). At 125°C ambient, junction temperature reaches 150°C-the rated maximum-when dissipating 400 mW. Derating is required above 70°C ambient; for example, at 100°C ambient, max dissipation drops to ~114 mW.