Texas Instruments LMT86LPGM

Overview

LMT86LPGM from Texas Instruments is a precision analog CMOS temperature sensor in TO-92S through-hole package, delivering ±0.4°C typical accuracy over –50°C to 150°C, –10.9 mV/°C output slope, 2.2 V minimum supply voltage, and 5.4 µA quiescent current - deployed in smoke detectors, automotive infotainment, and drone thermal monitoring.

For engineers reviewing the LMT86LPGM datasheet, LMT86LPGM pinout, LMT86LPGM application, or LMT86LPGM equivalent, key selection criteria include its fast 10 s thermal time constant (1.2 m/s airflow), push-pull output with ±50 µA drive, short-circuit protection, and footprint compatibility with LM20/LM35 for drop-in analog temperature sensing upgrades.

Technical Context

The LMT86LPGM uses a forward-biased base-emitter junction as its sensing element, buffered by a rail-to-rail CMOS amplifier with push-pull output stage - enabling low-impedance sourcing and sinking without external components. Its transfer function follows a parabolic model (–10.888 mV/°C slope + –0.00347 mV/°C² curvature) centered at 30°C, reflected precisely in the published 151-point transfer table.

Thermal response is optimized via 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 (TO-92S) and self-heating error <0.014°C at 5 V/30°C - critical for off-board mounting in heat detectors and engine bay sensors.

Key Specifications

Pinout & Package

TO-92S (LPG) through-hole package: 4.00 mm × 3.15 mm body, straight leads, GND pin thermally bonded to die backside for optimal thermal conduction.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LMT86LPGM, LMT85LP offers lower supply voltage flexibility but sacrifices sensitivity and wide-range accuracy; LM35DMX/NOPB provides industry-standard positive output but demands higher supply and lacks robustness against wiring faults.

Availability

LMT86LPGM is available at Aetrix Electronics and suitable for smoke detectors, automotive infotainment systems, and drone thermal monitoring requiring stable component supply across long production lifecycles.

Supply support for LMT86LPGM 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 headquartered in Dallas, Texas, designing analog and embedded processing chips for industrial, automotive, and consumer applications.

The LMT86 family was engineered specifically for high-accuracy, low-power analog temperature sensing in space-constrained and thermally dynamic environments - emphasizing fast response, wide operating range, and direct ADC interface capability.

FAQ

What is the thermal time constant of the LMT86LPGM, and how does it impact smoke detector response?

The LMT86LPGM has a thermal time constant of 10 seconds under 1.2 m/s airflow, measured in its TO-92S package. This enables detection of rapid temperature rises per UL 217 fire alarm standards - for example, a 10°C/min ramp is tracked with <2°C lag. The GND pin's direct thermal coupling to the die ensures this performance is maintained when mounted on metal detector housings or heat sinks. LMT86LPGM achieves this without external thermal mass, unlike thermistors requiring epoxy encapsulation.

Can the LMT86LPGM operate directly from a 2.2 V lithium battery without regulation?

Yes, the LMT86LPGM is fully specified down to 2.2 V supply voltage and draws only 5.4 µA quiescent current - making it ideal for direct connection to aging or partially discharged 2.2–3.6 V lithium primary cells. Its output remains monotonic and accurate across this range, with line regulation of 200 µV/V. No LDO or charge pump is needed, reducing bill-of-materials cost and PCB area. LMT86LPGM maintains ±0.4°C accuracy even at minimum VDD.

How does the LMT86LPGM's push-pull output interface with a microcontroller ADC input?

The LMT86LPGM's push-pull output delivers ±50 µA drive strength, enabling direct charging of typical SAR ADC sampling capacitors (e.g., 10–30 pF) without an op-amp buffer. It supports capacitive loads up to 1100 pF; for larger loads, a series resistor (e.g., 800 Ω for 1 µF) is recommended. LMT86LPGM's 0.7 ms power-on time ensures stable output before ADC sampling begins - critical for low-duty-cycle battery-powered systems.

Is the LMT86LPGM pin-compatible with the LM35, and what design changes are needed?

Yes, the LMT86LPGM in TO-92S package shares identical pinout (VDD–OUT–GND), outline dimensions, and lead spacing with the LM35, enabling direct replacement on existing boards. Key differences: LMT86LPGM has inverted output polarity (–10.9 mV/°C vs. +10 mV/°C), operates down to 2.2 V (vs. 4 V), and includes short-circuit protection. Firmware must invert ADC readings or adjust scaling; no hardware changes are required. LMT86LPGM retains LM35's mechanical fit while improving performance.

What is the maximum allowable capacitive load on the LMT86LPGM output without signal integrity degradation?

The LMT86LPGM is characterized to drive up to 1100 pF capacitively without added series resistance - sufficient for most MCU ADC inputs and RC filtering networks. For loads exceeding 1100 pF (e.g., long cables or high-C filters), TI recommends adding a series resistor: 800 Ω for 1 µF, 1.5 kΩ for 100–999 nF, or 3 kΩ for 1.1–99 nF. This prevents ringing and ensures monotonic settling. LMT86LPGM's push-pull architecture maintains stability across this full range without external compensation.