NXP Semiconductors LM75BD,112

Overview

LM75BD,112 from NXP Semiconductors is a digital temperature sensor and thermal watchdog IC with I²C interface, 0.125 °C resolution, ±2 °C accuracy from −25 °C to +100 °C, and open-drain overtemperature shutdown output (OS). It operates from 2.8 V to 5.5 V and supports up to eight devices on one bus via A0–A2 address pins. Used in PC thermal management for fan control and system throttling.

For engineers reviewing the LM75BD,112 datasheet, LM75BD,112 pinout, LM75BD,112 application, or LM75BD,112 equivalent, key selection criteria include its 11-bit sigma-delta ADC, programmable Tos/Thyst thresholds, OS comparator/interrupt mode selection, fault queue configuration, and SO8 package compatibility with legacy LM75 designs.

Technical Context

The LM75BD,112 integrates an on-chip bandgap temperature sensor with a dedicated 11-bit sigma-delta ADC, delivering 0.125 °C resolution and automatic 100 ms conversion cycles in normal mode. Its I²C interface complies with standard 20 Hz–400 kHz timing and includes bus fault timeout (≥50 ms) to prevent lockup.

Configuration is managed via an 8-bit Conf register controlling shutdown mode (bit B0), OS operation mode (comparator/interrupt, bit B1), OS polarity (HIGH/LOW, bit B2), and fault queue depth (1/2/4/6 consecutive faults, bits B3–B4). Temperature data resides in a read-only 16-bit Temp register containing 11 valid MSBs in two's complement format.

Key Specifications

Pinout & Package

LM75BD,112 is housed in an 8-pin SO8 package (SOT96-1), 3.9 mm body width, surface-mount plastic small outline format.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STLM75CDT and MAX31820MUA+, the LM75BD,112 offers superior I²C bus resilience via guaranteed 50 ms fault timeout, tighter −25 °C to +100 °C accuracy (±2 °C), and seamless pin/register compatibility with legacy LM75 designs-making it optimal for retrofit thermal upgrades in PC, server, and industrial controller platforms.

Availability

LM75BD,112 is available at Aetrix Electronics and suitable for server thermal management, industrial PLC protection, and embedded network switch fan control requiring stable component supply across long production lifecycles.

Supply support for LM75BD,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 LM75B product line delivers highly integrated, I²C-based digital temperature sensors designed for reliable thermal monitoring and autonomous overtemperature protection in space-constrained embedded systems.

FAQ

What is the default power-up configuration of the LM75BD,112?

At power-up, the LM75BD,112 initializes in normal operation mode with OS comparator mode enabled, Tos set to 80 °C, Thyst at 75 °C, OS active LOW, and fault queue = 1. This allows immediate stand-alone thermostat functionality without host initialization. The LM75BD,112 retains this state until modified via I²C writes to the Conf, Tos, or Thyst registers.

How does the LM75BD,112 handle I²C bus faults, and why is this important?

The LM75BD,112 implements a bus fault time-out that resets the I²C interface if SDA remains LOW for ≥50 ms, releasing the bus and awaiting a new START condition. This prevents permanent bus hang during communication errors-a critical reliability feature in noisy industrial environments. The LM75BD,112's guaranteed 50 ms timeout distinguishes it from alternatives lacking this protection.

Can the LM75BD,112 be used in shutdown mode while retaining I²C accessibility?

Yes-the LM75BD,112 supports full I²C register read/write access in shutdown mode, where the sigma-delta converter is disabled and Temp register holds the last valid reading. Power consumption drops to 1.0 μA, making it ideal for battery-backed thermal logging. The LM75BD,112 maintains its I²C address and responds to commands, enabling configuration updates or status checks without waking the main system.

What is the significance of the 11-bit temperature data format in the LM75BD,112 Temp register?

The LM75BD,112 stores temperature as an 11-bit two's complement value in the Temp register, yielding 0.125 °C resolution across −55 °C to +125 °C. Only the 11 most significant bits of the 16-bit register are valid; the 5 LSBs of the LSByte are zero-padded and must be ignored. This format enables precise thermal drift analysis-critical for applications like medical equipment calibration where sub-degree stability is mandatory-and the LM75BD,112 delivers this resolution natively without interpolation.

How does the fault queue feature improve thermal reliability in the LM75BD,112?

The LM75BD,112's programmable fault queue (1/2/4/6 consecutive overtemperature events) prevents false OS activation caused by transient noise or short thermal spikes. By requiring multiple confirmed conversions above Tos before asserting OS, the LM75BD,112 ensures only sustained thermal violations trigger action-enhancing system robustness in electrically noisy environments like motor drives or switching power supplies. This behavior is configured via bits B3–B4 in the Conf register.