Texas Instruments LMT87LP

Overview

LMT87LP from Texas Instruments is a precision analog temperature sensor in TO-92 through-hole package, delivering ±0.4°C typical accuracy over –50°C to +150°C, –13.6 mV/°C output slope, 2.7-V to 5.5-V supply operation, and 5.4-µA quiescent current. It serves as a direct replacement for thermistors in off-board thermal monitoring applications such as smoke detectors and automotive powertrain sensors.

For engineers reviewing the LMT87LP datasheet, LMT87LP pinout, LMT87LP application, or LMT87LP equivalent, this page delivers verified technical context, real-world thermal response data (10-s typical time constant in 1.2 m/s airflow), package-specific R_θJA = 167°C/W, push-pull output drive capability (±50 µA), and validated alternatives for cost-sensitive or layout-constrained designs.

Technical Context

The LMT87LP uses a forward-biased base-emitter junction as its sensing element, buffered by a Class-AB amplifier with push-pull output stage-enabling low-impedance sourcing and sinking up to ±50 µA without external components. Its transfer function is defined by a parabolic equation (–13.6 mV/°C slope with second-order correction) and referenced to Table 3 in the datasheet for <0.6°C error across –50°C to +150°C.

Thermal performance is optimized via direct die-to-GND thermal path: the GND pin serves as the primary heat conduction route, making PCB land pattern and mounting method critical for accuracy. Self-heating error remains below 0.015°C at 5.4 µA supply current and 2 µA load, confirmed by junction-to-ambient thermal resistance of 167°C/W under natural convection.

Key Specifications

Pinout & Package

TO-92 package (4.30 mm × 3.50 mm), through-hole, straight leads; GND pin (Pin 3) serves as primary thermal conduction path to PCB copper.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LMT87LP, LMT87LPG offers superior thermal responsiveness for environmental sensing, while LMT86LP trades sensitivity for broader supply tolerance-both maintain identical TO-92 mechanical fit and functional interface, enabling board-level substitution with minimal validation.

Availability

LMT87LP is available at Aetrix Electronics and suitable for automotive powertrain monitoring, smoke and heat detectors, industrial motor winding protection, and drone thermal management requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LMT87LP 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, embedded processing, and digital signal technologies, with decades of expertise in precision sensing and automotive-grade reliability.

The LMT87LP belongs to TI's LMT8x family of analog-output CMOS temperature sensors, designed specifically for cost-sensitive, high-accuracy thermal monitoring where thermistor replacement, low power, and fast thermal response are critical system requirements.

FAQ

What is the thermal time constant of the LMT87LP, and how is it measured?

The LMT87LP has a thermal time constant of 10 seconds typical under 1.2 m/s airflow, as measured per JEDEC JESD51-1 for TO-92 packages. This value reflects the time required for the sensor to reach 63.2% of a step-change temperature, validated using standardized thermal response testing with calibrated hot/cold air streams. The LMT87LP achieves this performance due to its low-mass TO-92 construction and direct die-to-GND thermal path.

Does the LMT87LP require external calibration to achieve ±0.4°C accuracy?

No, the LMT87LP achieves ±0.4°C typical accuracy (20°C–40°C, VDD = 3.4–5.5 V) without external calibration. This specification is factory-trimmed and guaranteed across process, voltage, and temperature variations. The device uses a parabolic transfer function (–13.6 mV/°C slope with second-order correction) documented in Table 3 of the datasheet, enabling high-accuracy look-up table or polynomial compensation in host firmware if needed.

Can the LMT87LP drive an ADC input directly, and what is the maximum capacitive load?

Yes, the LMT87LP can drive SAR ADC inputs directly thanks to its ±50-µA push-pull output. It supports capacitive loads up to 1100 pF without series resistance or filtering. For loads exceeding 1100 pF, a series resistor (e.g., 800 Ω for 1 µF) is recommended per Table 4 in the datasheet to maintain stability and minimize settling error-critical for high-resolution ADC sampling.

How does the GND pin function thermally in the LMT87LP TO-92 package?

In the LMT87LP, the GND pin (Pin 3) is electrically and thermally connected to the backside of the silicon die, serving as the primary thermal conduction path to the PCB. To maximize accuracy and response speed, the GND pad must be connected to a large copper area (≥100 mm²) with multiple thermal vias-this minimizes thermal resistance between die and ambient, reducing self-heating error to <0.015°C under typical operating conditions.

Is the LMT87LP pin-compatible with the LM35 or LM20 temperature sensors?

Yes, the LMT87LP is footprint- and pin-compatible with the LM35 and LM20 in TO-92 packages: VDD (Pin 1), OUT (Pin 2), GND (Pin 3). However, output polarity differs-the LMT87LP output decreases with rising temperature (–13.6 mV/°C), whereas LM35 increases (+10 mV/°C). Firmware or signal conditioning must account for this inversion, but no PCB changes are required for mechanical replacement.