Texas Instruments LM334H/NOPB

Overview

LM334H/NOPB from Texas Instruments is a 3-terminal adjustable current source optimized for precision temperature sensing and low-power biasing, delivering programmable output from 1 μA to 10 mA with ±3% initial accuracy, 0.02%/V current regulation, and operation across 1 V to 40 V supply range. It functions as a true floating two-terminal device in series with load, enabling remote Kelvin-sensing applications without accuracy loss over long wires.

For engineers reviewing the LM334H/NOPB datasheet, LM334H/NOPB pinout, LM334H/NOPB application, or LM334H/NOPB equivalent, this page provides verified technical context, validated pin configuration, real-world use cases in temperature instrumentation and LED biasing, and confirmed alternative parts with documented functional trade-offs.

Technical Context

The LM334H/NOPB operates as a floating current source where output current I_SET is set by an external resistor R_SET via the relationship I_SET = 67.7 mV / R_SET at 25°C, with inherent +0.336%/°C temperature coefficient directly proportional to absolute temperature (°K). Its internal architecture eliminates need for separate power rails, supporting true 2-terminal operation.

It exhibits reverse voltage tolerance up to 20 V, draws only microamperes under reverse bias, and maintains stable regulation down to 0.8 V minimum operating voltage at low set currents. Thermal self-heating effects are quantified: at 1 mA and 1 V drop, junction rise is ≈0.4°C, inducing ≈0.132% current shift due to its 0.33%/°C tempco.

Key Specifications

Pinout & Package

LM334H/NOPB uses the TO-99 metal can package (package code NDV), a hermetically sealed 3-pin through-hole package with center-tab thermal path. Pin 1 is marked by a dot; Pin 2 is the case (V−); Pin 3 is V+; the SET terminal is internally connected to Pin 2 and requires external connection to R_SET.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM334H/NOPB, LM334Z/NOPB offers identical functionality in lower-cost plastic packaging but sacrifices thermal robustness and hermetic reliability, while REF200AU provides superior accuracy and dual outputs at the expense of programmability and temperature-sensing utility.

Availability

LM334H/NOPB is available at Aetrix Electronics and suitable for industrial temperature transmitters, LED bias networks, micropower sensor excitation, and low-voltage reference driver applications requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for LM334H/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 is a global semiconductor leader specializing in analog and embedded processing technologies, with decades of expertise in precision analog ICs and industrial-grade components.

The LM334H/NOPB belongs to TI's legacy precision current source family, engineered specifically for temperature sensing, remote biasing, and low-power instrumentation where stability, simplicity, and 2-terminal operation are essential design requirements.

FAQ

What is the operating temperature range of the LM334H/NOPB?

The LM334H/NOPB is specified for operation from −55°C to +125°C, matching the LM134 grade rather than the commercial LM334 (0°C to +70°C). This extended range is enabled by its TO-99 metal can package and internal design, making it suitable for aerospace, automotive under-hood, and industrial control applications where ambient extremes occur. The LM334H/NOPB retains full electrical specifications-including ±3% initial accuracy and 0.02%/V regulation-across this entire range.

How do I calculate the external resistor value for a desired set current with LM334H/NOPB?

At 25°C, the LM334H/NOPB establishes set current using I_SET = 67.7 mV / R_SET. For example, to achieve 1 mA, R_SET = 67.7 Ω. The LM334H/NOPB datasheet specifies that I_SET increases by +0.336%/°C, so for temperature-compensated designs, R_SET must be selected with appropriate tempco (e.g., <20 ppm/°C metal film). Lead resistance must be minimized-0.7 Ω adds 1% error at 1 mA-so R_SET should be placed adjacent to the LM334H/NOPB pins.

Can the LM334H/NOPB be used as a temperature sensor, and what accuracy can be expected?

Yes-the LM334H/NOPB is explicitly designed for remote temperature sensing, with output current directly proportional to absolute temperature (I_SET ∝ T in °K). Using a single-point gain trim at 25°C, slope error can be reduced to <±1%, yielding ±0.5°C accuracy from 0°C to 70°C. The LM334H/NOPB's hermetic TO-99 package minimizes thermal lag and humidity-induced drift, outperforming plastic-packaged variants in long-term stability for temperature instrumentation.

Does the LM334H/NOPB require a separate power supply or ground connection?

No-the LM334H/NOPB operates as a true floating 2-terminal current source. It requires only two connections: one to the positive side of the load (V+) and one to the negative side (V−/SET). There is no dedicated ground, V_CC, or reference pin. This architecture eliminates ground-loop errors and simplifies integration into high-side or isolated current paths-exactly as implemented in the LM334H/NOPB's standard 2-terminal configuration shown in Figure 21 of the datasheet.

What is the maximum power dissipation and thermal resistance of the LM334H/NOPB?

The LM334H/NOPB has a maximum power dissipation of 400 mW and a junction-to-ambient thermal resistance (θ_JA) of 440°C/W in the TO-99 package. At 10 mA and 40 V drop, power dissipation reaches 400 mW-pushing thermal limits. In practice, continuous operation above 200 mW requires heatsinking the metal can or limiting voltage drop. The LM334H/NOPB's θ_JC is 32°C/W, confirming the case as the primary thermal path-making mechanical mounting to a metal chassis highly effective for thermal management.