Texas Instruments LMT84LPGM

Overview

LMT84LPGM from Texas Instruments is a precision analog-output CMOS temperature sensor in TO-92S through-hole package, delivering ±0.4°C typical accuracy over –50°C to +150°C, –5.5 mV/°C output gain, 5.4 µA quiescent current, and 10-s thermal time constant (1.2 m/s airflow), used for off-board thermal monitoring in smoke detectors and industrial enclosures.

For engineers reviewing the LMT84LPGM datasheet, LMT84LPGM pinout, LMT84LPGM application, or LMT84LPGM equivalent, this page provides verified technical context, real-world design meaning of specifications, validated pin functions, confirmed alternative options, and supply support for production integration.

Technical Context

The LMT84LPGM uses a forward-biased base-emitter junction as its sensing element, buffered by a rail-to-rail push-pull amplifier with ±50 µA drive capability-enabling direct interface to SAR ADC sampling capacitors without external buffering. Its output voltage is inversely proportional to temperature and exhibits slight parabolic nonlinearity, accurately modeled by TI's published transfer table (–50°C to +150°C) and quadratic equation.

Thermal performance is enhanced by direct die-to-GND thermal path: the GND pin serves as both electrical reference and primary heat conduction path, yielding R_θJA = 130.4°C/W (natural convection). Self-heating error remains below 0.015°C under typical load conditions due to ultra-low 5.4 µA supply current and minimal power dissipation.

Key Specifications

Pinout & Package

TO-92S (3-pin, through-hole, 4.00 mm × 3.15 mm body) with straight leads; GND pin thermally connected to die backside for optimal thermal coupling.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar analog-output temperature sensing applications.

Compared with LMT84LPGM, LMT85LP offers higher sensitivity but sacrifices 1.5-V operation, while LM35DMX/NOPB provides pin-compatible form factor with positive output polarity but consumes 10× more current and responds 3× slower-making LMT84LPGM optimal for battery-powered, fast-response thermal safety systems.

Availability

LMT84LPGM is available at Aetrix Electronics and suitable for smoke detectors, drone battery packs, industrial motor controllers, and automotive cabin climate sensors requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for LMT84LPGM 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 company specializing in analog, embedded processing, and digital signal technologies, with leadership in precision sensing and low-power signal conditioning.

The LMT84LPGM belongs to TI's LMT8x family of analog-output CMOS temperature sensors, designed specifically for cost-sensitive, battery-operated, and thermally responsive applications where accuracy, speed, and ultra-low power are critical.

FAQ

What is the thermal time constant of the LMT84LPGM and how is it measured?

The LMT84LPGM has a thermal time constant of 10 seconds typical under 1.2 m/s airflow, measured per JEDEC JESD51-1 using standardized forced-air convection. This value reflects the time required for the sensor to reach 63.2% of a step-change in ambient temperature and is validated in Figure 10 of the official SNIS167E datasheet. The TO-92S package geometry and direct die-to-GND thermal path enable this fast response, making LMT84LPGM suitable for dynamic thermal monitoring where thermistor lag is unacceptable.

Does the LMT84LPGM require external calibration to achieve ±0.4°C accuracy?

No, the LMT84LPGM achieves ±0.4°C typical accuracy (–50°C to +150°C, VDD ≥ 2.3 V) without external calibration. This specification is factory-trimmed and guaranteed across process, voltage, and temperature. The datasheet accuracy table (Section 7.5) confirms that the ±0.4°C limit includes line regulation and output voltage shift effects. Users may apply the provided quadratic equation or TI's full transfer table for higher precision, but LMT84LPGM delivers specified accuracy out-of-box in production systems.

Can the LMT84LPGM drive an ADC input directly, and what is the maximum capacitive load it supports?

Yes, the LMT84LPGM can drive SAR ADC inputs directly thanks to its ±50 µA push-pull output stage. It supports up to 1100 pF capacitive load without series resistance (per Section 8.4.3). For loads ≤100 pF-typical of most microcontroller ADC inputs-no external components are needed. When driving larger capacitive loads (e.g., >1 nF), TI recommends adding a series resistor (e.g., 3 kΩ for 1.1–99 nF) to ensure stability, as documented in Figure 12 and Table 4 of the LMT84LPGM datasheet.

How does the LMT84LPGM handle supply voltage variation, and what is its line regulation?

The LMT84LPGM exhibits 200 µV/V typical line regulation (Section 7.6), meaning output voltage shifts by only 200 µV per volt change in VDD. This low sensitivity ensures stable readings across battery discharge (e.g., 3.6 V → 2.8 V) without recalibration. The datasheet confirms that all accuracy specs-including the ±0.4°C typical-already include line regulation effects, so no additional compensation is required. Output voltage remains monotonic across the full 1.5–5.5 V range, with shift occurring gradually over ~200 mV VDD change.

Is the LMT84LPGM pin-compatible with the LM35, and what are the key electrical differences?

Yes, the LMT84LPGM is footprint- and pin-compatible with the LM35 in TO-92 packages (VDD–GND–OUT pinout matches LM35's VCC–GND–OUT), enabling mechanical drop-in replacement. Electrically, LMT84LPGM differs by offering inverse output slope (–5.5 mV/°C vs. +10 mV/°C), lower supply voltage (1.5 V vs. 4 V min), 10× lower quiescent current (5.4 µA vs. 50 µA), and faster thermal response (10 s vs. ~30 s). These differences require firmware sign inversion and supply validation but deliver significant power and speed advantages.