STMicroelectronics LM234DT

Overview

LM234DT from STMicroelectronics is a three-terminal adjustable current source optimized for precision biasing, temperature sensing, and low-power reference applications. It delivers programmable current from 1µA to 10mA with ±3% initial accuracy, 0.02%/V regulation, and operates across 1V–40V supply range. Its 64mV control voltage at +25°C is directly proportional to absolute temperature (°K), enabling accurate remote thermal measurement.

For engineers reviewing the LM234DT datasheet, LM234DT pinout, LM234DT application, or LM234DT equivalent, key selection criteria include its wide dynamic voltage range, temperature-proportional output, low minimum operating voltage (0.8V at 2µA), shunt capacitance (15pF), and SO-8 package compatibility with surface-mount production workflows.

Technical Context

The LM234DT implements a two-transistor current mirror architecture with on-chip temperature-sensing junction, where the ADJ pin voltage (64mV @ 25°C) scales linearly with absolute temperature (1µV/K). Its set current I_set = 67.7mV/R_set at 25°C, and full-scale drift is compensated via external resistor/diode networks to achieve zero temperature coefficient.

It functions as both a precision current source and a Kelvin-referenced temperature transducer. Reverse voltage tolerance up to 20V enables AC-coupled operation, while internal thermal feedback limits self-heating effects-critical for stable bias in analog front-ends and sensor interfaces requiring <1% slope error after single-point gain trim.

Key Specifications

Pinout & Package

LM234DT is housed in an SO-8 plastic micropackage (ECOPACK® compliant, lead-free second-level interconnect), measuring 4.90mm × 3.90mm × 1.25mm (typ.), with 1.27mm pitch gull-wing leads.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM334DT and REF200AU, the LM234DT uniquely balances programmability, temperature transduction capability, and −25°C to +100°C industrial operating range-making it optimal for embedded sensor nodes requiring field-calibratable thermal monitoring and supply-voltage resilience.

Availability

LM234DT is available at Aetrix Electronics and suitable for remote temperature sensing, low-voltage reference bias, and in-line current limiting applications requiring stable component supply across automotive under-hood, industrial PLC, and portable instrumentation designs.

Supply support for LM234DT 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing silicon solutions for automotive, industrial, and consumer markets since 1987.

The LM134/LM234/LM334 family was developed to deliver precision, temperature-aware current sources for sensor signal conditioning and analog biasing-prioritizing Kelvin-proportional output, wide supply tolerance, and robustness in harsh electrical environments.

FAQ

What is the minimum voltage required for LM234DT to regulate at 10µA?

The LM234DT requires a minimum V+ to V− voltage of 0.8V when set for 2µA–100µA operation. At 10µA, this threshold remains 0.8V, verified per Table 2 in the ST datasheet. Below this, the device enters dropout and I_set collapses nonlinearly. Layout best practices require minimizing trace resistance between V+ and the supply rail to maintain headroom.

Can LM234DT be used as a temperature sensor without external components?

Yes-the LM234DT inherently functions as a 227µV/K temperature transducer. With only a precision current-sense resistor at V+, its output current scales linearly with absolute temperature. No additional active components are needed, though a low-TC resistor (≤20ppm/°C) and 3-wire connection are recommended to hold slope error below 1% across −25°C to +100°C.

How does reverse voltage affect LM234DT performance?

LM234DT tolerates up to −20V from V+ to V−, drawing only several microamperes in reverse. This enables safe use in AC-coupled circuits and polarity-insensitive sensor interfaces. However, sustained reverse bias above −5V may induce minor leakage current shifts; ST recommends limiting reverse duration in high-reliability applications per Absolute Maximum Ratings Table 1.

Why does LM234DT require careful R_set placement near the ADJ pin?

The ADJ pin senses a sub-100mV reference voltage; even 0.7Ω of trace or contact resistance introduces 1% current error at 1mA. Sockets and long leads create thermocouple voltages that offset the 64mV baseline. ST explicitly advises mounting R_set adjacent to the ADJ pin and avoiding sockets-verified in Section 4.5 of the application note.