NXP Semiconductors LM75AD/G-T

Overview

LM75AD/G-T 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 for system-level thermal monitoring and autonomous thermal protection in embedded controllers.

For engineers reviewing the LM75AD/G-T datasheet, LM75AD/G-T pinout, LM75AD/G-T application, or LM75AD/G-T equivalent, this page delivers verified technical context, exact pin functions, real-world thermal management use cases, and validated alternative options - all grounded in NXP's official LM75A product data sheet Rev. 04 (2007).

Technical Context

The LM75AD/G-T implements a sigma-delta A-to-D converter with 11-bit 2's complement output for temperature measurement, using an on-chip band gap sensor. Its thermal watchdog logic compares the 9 MSB of the Temp register against programmable Tos and Thyst registers to drive the open-drain OS output in either comparator or interrupt mode.

Configuration is managed via an 8-bit Configuration register controlling shutdown mode (3.5 µA), OS polarity (active LOW/HIGH), OS mode (comparator/interrupt), and fault queue (1–6 consecutive trips). The device supports up to eight units on one I²C bus via three address pins (A2–A0), with slave address prefix '1001' and full 7-bit address determined by pin states.

Key Specifications

Pinout & Package

LM75AD/G-T is supplied in SO8 package (SOT96-1), 3.9 mm body width, 8-lead plastic small outline.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STLM75CDT and MAX6625ASA+, the LM75AD/G-T uniquely combines ±2 °C mid-range accuracy, programmable OS interrupt mode, and 3.5 µA shutdown current-making it optimal for thermally constrained embedded systems requiring both precision and autonomous alerting.

Availability

LM75AD/G-T is available at Aetrix Electronics and suitable for server thermal management, industrial PLC guarding, embedded storage control, and network switch ASIC protection requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LM75AD/G-T 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/G-T-is designed as a pin-compatible upgrade to the legacy LM75, delivering enhanced resolution (0.125 °C), wider supply range (2.8–5.5 V), and improved accuracy for embedded thermal monitoring and watchdog functions.

FAQ

What is the default power-up configuration of the LM75AD/G-T?

At power-up, the LM75AD/G-T initializes in normal operation mode with OS comparator mode enabled, Tos = 80 °C, Thyst = 75 °C, OS active LOW, and fault queue = 1. This allows immediate standalone thermostat operation without host initialization. The LM75AD/G-T retains these defaults unless modified via I²C writes to its Configuration, Tos, or Thyst registers.

How does the OS output behave in comparator versus interrupt mode on the LM75AD/G-T?

In comparator mode, the LM75AD/G-T's OS output asserts when temperature exceeds Tos and de-asserts when it falls below Thyst-behaving like a hardware thermostat. In interrupt mode, OS asserts on Tos crossing and remains latched until any register is read, enabling host-controlled thermal event acknowledgment. Mode selection is controlled by bit B1 in the Configuration register.

Can the LM75AD/G-T operate from a 3.3 V supply, and what is its typical supply current?

Yes, the LM75AD/G-T operates across 2.8 V to 5.5 V, making 3.3 V fully compliant. In normal mode with I²C inactive, supply current is typically 100 µA; in shutdown mode, it drops to 3.5 µA. These values are specified in NXP's LM75A datasheet Rev. 04 and confirmed across the full −55 °C to +125 °C range.

What is the temperature resolution and accuracy specification of the LM75AD/G-T?

The LM75AD/G-T provides 0.125 °C resolution via its 11-bit sigma-delta ADC. Accuracy is ±2 °C from −25 °C to +100 °C and ±3 °C from −55 °C to +125 °C. These specifications are measured per NXP's characterization and apply to the LM75AD/G-T in SO8 package under recommended operating conditions.

How many LM75AD/G-T devices can share the same I²C bus, and how is addressing managed?

Up to eight LM75AD/G-T devices can coexist on one I²C bus. Addressing uses a fixed 4-bit prefix '1001' plus three programmable bits (A2, A1, A0), yielding seven-bit slave addresses from 1001000 to 1001111. Each pin connects to VCC (logic 1) or GND (logic 0); floating pins are prohibited per NXP's design requirements.