NXP Semiconductors LM75AD,112

Overview

LM75AD,112 from NXP Semiconductors is a digital temperature sensor and thermal watchdog IC featuring an on-chip band gap sensor, 11-bit sigma-delta ADC, I²C-bus interface, open-drain OS output, and programmable overtemperature shutdown (80 °C default) and hysteresis (75 °C default). It operates from −55 °C to +125 °C with ±2 °C accuracy (−25 °C to +100 °C) and 0.125 °C resolution, used in system thermal management for embedded controllers and industrial equipment.

For engineers reviewing the LM75AD,112 datasheet, LM75AD,112 pinout, LM75AD,112 application, or LM75AD,112 equivalent, this page delivers verified technical context, exact pin functions, real-world use scenarios, validated alternatives, and supply support - all grounded in NXP's official LM75A product data sheet Rev. 04.

Technical Context

The LM75AD,112 implements a band gap temperature sensor paired with an 11-bit sigma-delta A-to-D converter, delivering 0.125 °C resolution via 2's complement 11-bit temperature data stored in the Temp register. Its I²C-bus interface supports up to eight devices on one bus using three address pins (A2–A0), with configurable slave address '1001' + A2A1A0.

It features dual-mode thermal detection: OS comparator mode (thermostat behavior: active above Tos, reset below Thyst) and OS interrupt mode (latched until register read), both with programmable fault queue (1/2/4/6 consecutive faults) and polarity (active HIGH/LOW). Power-up defaults include normal mode, Tos = 80 °C, Thyst = 75 °C, OS active LOW, and OS comparator mode.

Key Specifications

Pinout & Package

LM75AD,112 is supplied in an SO8 package (SOT96-1), 3.9 mm body width, plastic small outline format.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar digital temperature sensor and thermal watchdog applications.

Compared with STLM75DT and MAX31820MUA+, the LM75AD,112 uniquely combines I²C compatibility, 0.125 °C resolution, programmable fault queue, and dedicated open-drain OS output - making it optimal for deterministic, hardware-assisted thermal shutdown in industrial and embedded systems.

Availability

LM75AD,112 is available at Aetrix Electronics and suitable for server thermal management, industrial PLC protection, and embedded edge gateway designs requiring stable component supply, long-term lifecycle assurance, and guaranteed traceability.

Supply support for LM75AD,112 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

NXP Semiconductors is a global semiconductor company headquartered in Eindhoven, Netherlands, specializing in secure connectivity solutions for automotive, industrial, and IoT applications.

The LM75A family - including LM75AD,112 - was designed as a drop-in upgrade to the industry-standard LM75, delivering enhanced resolution and extended specification coverage across 2.8–5.5 V supplies for thermal monitoring in space-constrained, noise-prone industrial systems.

FAQ

What is the default power-up configuration of the LM75AD,112?

At power-up, the LM75AD,112 initializes in normal operation mode, OS comparator mode, Tos = 80 °C, Thyst = 75 °C, OS active LOW, and fault queue = 1. The pointer register defaults to 0, selecting the Temp register for immediate read access without sending a pointer byte. This allows the LM75AD,112 to function as a ready-to-use thermostat upon power application.

How does the LM75AD,112 achieve 0.125 °C temperature resolution?

The LM75AD,112 achieves 0.125 °C resolution through its 11-bit sigma-delta A-to-D converter, which outputs temperature data in 2's complement format stored in the Temp register. Only the 11 most significant bits are valid; the 5 least significant bits of the LSByte are zero and ignored. This resolution is confirmed in Table 9 and Section 7.4.3 of the NXP LM75A datasheet, and is intrinsic to the LM75AD,112's architecture - not dependent on external components or firmware interpolation.

Can the LM75AD,112 operate with a 3.3 V supply?

Yes, the LM75AD,112 operates reliably across 2.8 V to 5.5 V, including standard 3.3 V logic rails. Its VIH (HIGH-level input voltage) minimum is 0.7 × VCC, and VOL (LOW-level output voltage) remains ≤0.4 V at 3 mA sink - ensuring clean interfacing with 3.3 V microcontrollers and I²C peripherals. All electrical characteristics in Table 17 are specified across this full voltage range, confirming robust 3.3 V operation for the LM75AD,112.

What is the function of the OS output on the LM75AD,112?

OS is an open-drain overtemperature shutdown output that becomes active when measured temperature exceeds the programmed Tos threshold (and remains active per fault queue and OS mode). In comparator mode, it resets automatically when temperature falls below Thyst; in interrupt mode, it latches until any register is read. The LM75AD,112's OS pin drives cooling fans, safety relays, or MCU interrupt lines directly - eliminating need for external comparators or GPIO polling.

Is the LM75AD,112 pin-compatible with the original LM75?

Yes, the LM75AD,112 is explicitly designed as a pin-for-pin replacement for the industry-standard LM75, sharing identical SO8 (SOT96-1) packaging, pinout, and I²C protocol. Per Section 2 of the NXP datasheet, it offers improved 0.125 °C resolution and unified 2.8–5.5 V operation - meaning existing LM75 footprints and firmware require no modification to adopt the LM75AD,112.