Texas Instruments LM26CIM5X-NPA/NOPB

Overview

LM26CIM5X-NPA/NOPB from Texas Instruments is a factory-preset, ±3°C accurate digital-output thermostat with 45°C overtemperature shutdown trip point, open-drain active-low OS output, and programmable 2°C/10°C hysteresis via HYST pin. It integrates temperature sensor, reference, DAC, and comparator in a 5-pin SOT-23 package for thermal protection in microprocessor power supplies and fan control circuits.

For engineers reviewing the LM26CIM5X-NPA/NOPB datasheet, LM26CIM5X-NPA/NOPB pinout, LM26CIM5X-NPA/NOPB application, or LM26CIM5X-NPA/NOPB equivalent, key selection criteria include trip point accuracy (±3°C), VTEMP analog output slope (−10.82 mV/°C), supply current (16 µA typical), hysteresis configuration (GND = 10°C, V+ = 2°C), and open-drain OS output compatibility with 3.3 V/5 V logic systems.

Technical Context

The LM26CIM5X-NPA/NOPB implements a precision analog temperature sensing front-end feeding an internal comparator with factory-trimmed reference and DAC, enabling fixed 45°C trip point detection without external components. Its VTEMP pin outputs a nonlinear voltage (V = −3.479×10⁻⁶(T−30)² − 1.082×10⁻²(T−30) + 1.8015 V) calibrated to ±2.5°C at 30°C.

Digital functionality centers on the open-drain OS output, which asserts LOW when die temperature exceeds 45°C and releases HIGH after cooling below (45°C − THYST). Hysteresis is selected externally: HYST = GND yields 11°C typical hysteresis (10°C nominal), while HYST = V+ yields 2°C typical hysteresis - both values are verified across −55°C to +120°C operating range.

Key Specifications

Pinout & Package

LM26CIM5X-NPA/NOPB uses a 5-pin SOT-23 (DBV) package measuring 2.90 mm × 1.60 mm, with thermal pad connected internally to GND (pin 2) for optimal junction-to-board heat transfer.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar thermostat applications.

Compared with LM26CIM5X-NPA/NOPB, LM26CIM5-RPA/NOPB offers higher trip point but identical hysteresis and output behavior, while MAX6505UTP45+T provides same trip point with push-pull output - reducing component count but requiring firmware logic inversion for interrupt handling.

Availability

LM26CIM5X-NPA/NOPB is available at Aetrix Electronics and suitable for microprocessor thermal management, fan control, and portable battery-powered systems requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for LM26CIM5X-NPA/NOPB 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 and embedded processing technologies, with leadership in precision analog ICs and industrial-grade temperature sensors.

The LM26 product line delivers factory-programmed thermostats for system-level thermal protection, designed specifically for reliability-critical applications including computing, industrial automation, and power electronics where consistent trip-point accuracy and low-power operation are essential.

FAQ

What is the exact trip temperature and hysteresis behavior of LM26CIM5X-NPA/NOPB?

The LM26CIM5X-NPA/NOPB has a fixed factory-set overtemperature trip point of 45°C. When die temperature reaches or exceeds 45°C, the OS output goes LOW. Hysteresis is programmable: connecting HYST to GND sets ~10°C hysteresis (OS returns HIGH when temperature falls to ~35°C), while connecting HYST to V+ sets ~2°C hysteresis (OS returns HIGH near 43°C). Trip accuracy is ±3°C across −55°C to +110°C.

Can LM26CIM5X-NPA/NOPB be used for undertemperature detection?

No. The LM26CIM5X-NPA/NOPB is configured exclusively for overtemperature shutdown (OS output) with a fixed 45°C trip point. Undertemperature (US) functionality is not implemented in this variant - it is factory-programmed for OS-only operation. For undertemperature detection, select LM26CIM5-HHD/NOPB (0°C US) or other US-specified variants listed in the Device Comparison Table.

How does the VTEMP pin function, and what is its practical use in system design?

The VTEMP pin on LM26CIM5X-NPA/NOPB outputs an analog voltage proportional to die temperature, following V = −3.479×10⁻⁶(T−30)² − 1.082×10⁻²(T−30) + 1.8015 V, with −10.82 mV/°C slope. It enables after-assembly PCB testing: applying known voltages to VTEMP verifies comparator and output stage functionality without thermal cycling. Its weak drive capability (1 µA source) requires high-impedance ADC input or series resistor for capacitive loads.

What are the power supply requirements and noise immunity characteristics of LM26CIM5X-NPA/NOPB?

LM26CIM5X-NPA/NOPB operates from 2.7 V to 5.5 V with typical supply current of 16 µA and maximum of 40 µA. It features excellent power supply noise rejection: false triggering was not observed under 400 kHz square wave (1 V_p-p), 2 kHz square wave (200 mV_p-p), or 100 Hz–1 MHz sine wave (200 mV_p-p) injected into V+, tested 1°C away from trip point. A 0.1 µF ceramic capacitor must be placed adjacent to V+ and GND pins.

Is LM26CIM5X-NPA/NOPB pin-compatible with other LM26 variants, and can it be substituted without PCB changes?

Yes. All LM26 variants, including LM26CIM5X-NPA/NOPB, use the identical 5-pin SOT-23 (DBV) package with standardized pinout (HYST, GND, VTEMP, V+, OS). Substitution between variants - such as LM26CIM5-RPA/NOPB (65°C) or LM26CIM5-SHA/NOPB (75°C) - requires no PCB changes. However, output logic polarity (active-low OS vs. active-high OS) and trip point differ by part number, so firmware interrupt handling and thermal design margins must be validated per variant.