Texas Instruments LM135AH

Overview

LM135AH from Texas Instruments is a precision 2-terminal Kelvin-referenced temperature sensor operating as a zener-like device with linear 10 mV/K output, ±1°C initial accuracy at 25°C, −55°C to +150°C operating range, and <1 Ω dynamic impedance. It delivers stable voltage output proportional to absolute temperature for high-accuracy thermal monitoring in industrial power supplies and battery management systems.

For engineers reviewing the LM135AH datasheet, LM135AH pinout, LM135AH application, or LM135AH equivalent, this page provides verified specifications, TO-46 package details, calibrated vs. uncalibrated functional modes, thermal time constant data, and real-world implementation guidance for surface-mount and cable-connected sensing.

Technical Context

The LM135AH functions as a 2-terminal temperature-dependent zener diode with output voltage directly proportional to absolute temperature (10 mV/K), enabling direct Kelvin-scale readout without signal conditioning. Its low 0.6 Ω typical dynamic impedance ensures minimal current-sensitivity error across its 0.4–5 mA operating range.

Calibration is supported via the ADJ pin using a single-point slope adjustment at 25°C (2.982 V), correcting scale-factor errors across the full −55°C to +150°C range. The device operates in two functional modes-uncalibrated (±2.7°C max error over full range) and calibrated (±1°C max error over full range)-with no external reference required.

Key Specifications

Pinout & Package

LM135AH is housed in a hermetic TO-46 metal can package (body size 4.699 mm × 4.699 mm) with three terminals: anode (+), cathode (−), and ADJ (calibration adjust). The package provides robust thermal coupling and long-term stability in high-reliability applications.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM135H and LM235AH/NOPB, the LM135AH offers RoHS compliance, guaranteed ±1°C initial accuracy, and full −55°C capability - making it optimal for new high-reliability designs requiring traceable environmental compliance and wide thermal coverage.

Availability

LM135AH is available at Aetrix Electronics and suitable for industrial power supply monitoring, battery thermal management, and HVAC system control requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for LM135AH 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 experience in precision analog sensors and industrial-grade ICs.

The LM135AH belongs to TI's LMx35 precision temperature sensor family, designed specifically for applications demanding high linearity, low drift, and direct Kelvin-scale output without external compensation circuitry.

FAQ

What is the operating temperature range of the LM135AH?

The LM135AH operates continuously from −55°C to +150°C, with intermittent capability up to +200°C. This range is validated per TI's SNIS160E datasheet and makes the LM135AH suitable for under-hood automotive, industrial motor drives, and aerospace thermal monitoring where extreme ambient conditions occur. The LM135AH maintains specified accuracy and stability across this full range when used within recommended bias current limits.

How does the ADJ pin on the LM135AH enable calibration?

The ADJ pin on the LM135AH allows single-point slope calibration by connecting an external potentiometer between the + and − terminals, with the wiper tied to ADJ. Adjusting the pot at 25°C (2.982 V) corrects gain error across the entire −55°C to +150°C range because the LM135AH's output is inherently linear versus absolute temperature. This eliminates need for multi-point calibration while preserving the LM135AH's 10 mV/K transfer function.

What package type is used for the LM135AH?

The LM135AH uses a hermetic TO-46 metal can package (NDV variant), measuring 4.699 mm × 4.699 mm. This package provides superior moisture resistance, thermal stability, and long-term reliability compared to plastic TO-92 alternatives. The TO-46 housing also enables efficient thermal coupling to heatsinks or PCB copper planes, supporting accurate surface-temperature measurement in the LM135AH's intended applications.

Can the LM135AH be used with a microcontroller ADC without signal conditioning?

Yes - the LM135AH's low 0.6 Ω dynamic impedance and linear 10 mV/K output allow direct connection to most microcontroller ADC inputs. At 1 mA bias, its output spans ~2.43 V (−55°C) to ~4.23 V (+150°C), fitting standard 3.3 V or 5 V ADC references. For best results, use a low-ESR decoupling capacitor near the LM135AH and route traces away from noise sources. The LM135AH's inherent linearity avoids need for lookup tables or polynomial correction in firmware.

What is the maximum allowable bias current for the LM135AH?

The LM135AH supports a continuous bias current range of 0.4 mA to 5 mA, with absolute maximum ratings permitting up to 15 mA reverse current for short durations. Operating above 5 mA increases self-heating error and may degrade long-term stability. For optimal accuracy and minimal thermal drift, TI recommends 1 mA bias - a value that balances output signal level, power dissipation (<4.2 mW at 150°C), and noise performance in the LM135AH's specified operating conditions.