STMicroelectronics LM235DT

Overview

LM235DT from STMicroelectronics is a precision 2-terminal Zener-based temperature sensor calibrated in Kelvin, delivering 10 mV/°K linear output with ±1°C initial accuracy over –40°C to +125°C. It operates from 450 µA to 5 mA, exhibits <1 Ω dynamic impedance, and is housed in an SO-8 plastic micropackage. Used in industrial environmental monitoring systems for real-time ambient temperature feedback.

For engineers reviewing the LM235DT datasheet, LM235DT pinout, LM235DT application, or LM235DT equivalent, key selection criteria include absolute temperature linearity (10 mV/°K), low self-heating error (<0.5°C calibrated), SO-8 thermal response time (10 s in air), and compatibility with single-point slope calibration at 25°C.

Technical Context

The LM235DT functions as a programmable Zener diode whose breakdown voltage tracks absolute temperature linearly at 10 mV/°K, enabling direct Kelvin-to-voltage conversion without signal conditioning. Its two-terminal architecture eliminates need for external bias resistors in basic configurations.

Calibration is performed at +25°C (298.15 K), yielding 2.98 V nominal output; uncalibrated error remains ≤2°C across full range, while calibrated error drops to ≤1°C. Dynamic impedance stays below 0.6 Ω at 1 mA, ensuring minimal load-induced voltage shift.

Key Specifications

Pinout & Package

LM235DT is supplied in an SO-8 plastic micropackage (JEDEC MS-012AC), with 8-pin surface-mount footprint and gull-wing leads. The package supports reflow soldering per JEDEC J-STD-020 and features lead-free second-level interconnect (ECOPACK®).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar precision Kelvin-referenced temperature sensing applications.

Compared with LM335DT and TSYS01, the LM235DT offers optimal balance of analog simplicity, industrial-grade temperature range, and calibrated accuracy-making it preferred for legacy analog systems and cost-sensitive industrial controllers where ADC resources are limited.

Availability

LM235DT is available at Aetrix Electronics and suitable for industrial environmental monitoring, automotive cabin sensing, and power supply thermal protection requiring stable component supply and long-term lifecycle assurance.

Supply support for LM235DT 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 analog, mixed-signal, power, and microcontroller products for industrial, automotive, and consumer markets.

The LM235DT belongs to ST's precision analog sensor family, engineered specifically for high-reliability temperature measurement in harsh environments where linearity, long-term stability, and Kelvin-scale output are mandatory.

FAQ

What is the recommended operating current for optimal accuracy?

The LM235DT achieves best accuracy at 1 mA operating current, where dynamic impedance is minimized (0.5 Ω) and self-heating error is constrained to <0.1°C. Currents between 450 µA and 5 mA are valid, but deviations beyond ±10% of 1 mA increase thermal drift and reduce effective resolution.

Can the LM235DT be used without calibration in production systems?

Yes-the LM235DT delivers ±1°C initial accuracy at +25°C without calibration, sufficient for many industrial monitoring applications. For tighter tolerance, a single-point 25°C calibration adjusts slope error across the full –40°C to +125°C range, achieving ≤0.5°C error.

How does the SO-8 package affect thermal response compared to TO-92?

The SO-8 package provides faster thermal response (10 s in 0.5 m/s air) than TO-92 (80 s in still air) due to lower thermal mass and improved PCB heat sinking. This makes LM235DT more responsive to rapid ambient changes in fan-cooled enclosures.

Is the ADJ pin required for basic operation?

No-the ADJ pin is optional and used only for precision slope calibration. In standard configurations, it can be left unconnected or tied to V+ through a trim potentiometer; the device functions fully as a 2-terminal device with V+ and V– pins only.