Texas Instruments LMT85LP

Overview

LMT85LP from Texas Instruments is a precision analog-output CMOS temperature sensor in TO-92 through-hole package, delivering ±0.4°C typical accuracy across –50°C to 150°C, −8.2 mV/°C output slope, 5.4 µA quiescent current, and 1.8-V minimum supply voltage - deployed in automotive infotainment clusters and smoke detectors where fast thermal response and low-power operation are critical.

For engineers reviewing the LMT85LP datasheet, LMT85LP pinout, LMT85LP application, or LMT85LP equivalent, key selection considerations include its inverse-linear analog output, TO-92 pin compatibility with LM35/LM20 footprints, thermal time constant (10 s @ 1.2 m/s airflow), and push-pull output drive capability for direct ADC interfacing without external buffering.

Technical Context

The LMT85LP 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 ±50 µA sourcing/sinking into capacitive loads up to 1100 pF. Its transfer function follows a slight parabolic shape, accurately modeled by TI's published 151-point transfer table (–50°C to 150°C) and linearized approximations.

Thermal coupling is enhanced by direct die attachment to the GND pin; self-heating error remains below 0.015°C at 5 V/2 µA load. The device operates with no external components, supports power cycling via GPIO-controlled VDD, and exhibits supply-noise attenuation >30 dB above 10 kHz per measured characteristics.

Key Specifications

Pinout & Package

Package: TO-92 (3-pin, through-hole, straight leads, body size 4.30 mm × 3.50 mm). Pin numbering follows JEDEC TO-92 standard with Pin 1 = VDD, Pin 2 = OUT, Pin 3 = GND.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LMT85LPG, the LMT85LP trades marginally slower thermal response for broader mechanical compatibility with legacy TO-92 footprints; compared with LMT84, it provides 49% higher output slope for improved ADC resolution without sacrificing accuracy or supply flexibility above 1.8 V.

Availability

LMT85LP is available at Aetrix Electronics and suitable for automotive infotainment clusters, smoke and heat detectors, and industrial appliance thermal monitoring requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for LMT85LP 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 and manufacturing analog ICs, embedded processors, and high-reliability components for industrial, automotive, and communications markets.

The LMT85LP belongs to TI's LMT8x family of precision analog temperature sensors, engineered specifically for cost-sensitive, low-power, and thermally dynamic applications where discrete thermistors lack linearity and digital sensors introduce complexity or latency.

FAQ

What is the pin configuration of the LMT85LP?

The LMT85LP uses a standard TO-92 package with three pins: Pin 1 is VDD (1.8–5.5 V supply), Pin 2 is OUT (analog voltage output inversely proportional to temperature), and Pin 3 is GND (power and thermal reference). This matches JEDEC TO-92 mechanical dimensions and pinout, ensuring compatibility with LM35/LM20 layouts. The die backside is bonded directly to the GND pin for optimal thermal conduction.

Does the LMT85LP require external components to operate?

No, the LMT85LP operates with only VDD, GND, and OUT connections - no external resistors, capacitors, or calibration components are needed. A 100-nF bypass capacitor on VDD within 5 cm is recommended for noisy environments, but not required for basic functionality. Its push-pull output eliminates the need for a pull-up resistor, and its internal bandgap reference ensures stable operation across voltage and temperature ranges.

How accurate is the LMT85LP over its full temperature range?

The LMT85LP achieves ±0.4°C typical accuracy from –50°C to +150°C at 1.8–5.5 V supply, with a maximum error of ±2.7°C across the same range. Accuracy varies slightly with supply voltage: ±0.3°C at 2.6–5.5 V (0–150°C), ±0.25°C at 2.9–5.5 V (–50–0°C). These values are specified per TI's AOQL testing and include line regulation effects but exclude DC load regulation - design assumes ≤50 µA output loading.

Can the LMT85LP drive an ADC input directly?

Yes, the LMT85LP's ±50 µA push-pull output can directly drive typical SAR ADC sampling capacitors (10–20 pF) without external buffering. It supports capacitive loads up to 1100 pF; for larger loads, a series resistor (e.g., 800 Ω for 1 µF) is recommended per TI's application guidance. The 0.7-ms power-on time and monotonic output ensure reliable acquisition in burst-sensing architectures using the LMT85LP.

What is the thermal time constant of the LMT85LP?

The LMT85LP (TO-92 package) has a thermal time constant of approximately 15 seconds under 1.2 m/s airflow, as derived from TI's characterization of the TO-92 variant. This is slower than the LMT85LPG (TO-92S, 10 s) due to its larger body size (4.30 mm × 3.50 mm vs. 4.00 mm × 3.15 mm), but still significantly faster than NTC thermistors. Mounting method (e.g., epoxy to metal surface) further influences effective response time in end equipment.