Texas Instruments LM76CHMX-5/NOPB

Overview

LM76CHMX-5/NOPB from Texas Instruments is a ±0.5°C accurate, 12-bit + sign digital temperature sensor with integrated thermal window comparator and I²C interface. It operates from 4.5V to 5.5V, delivers 0.0625°C resolution, and features dual open-drain outputs (INT and T_CRIT_A) for programmable over/under-temperature alerts and critical shutdown in PC thermal management systems.

For engineers reviewing the LM76CHMX-5/NOPB datasheet, LM76CHMX-5/NOPB pinout, LM76CHMX-5/NOPB application, or LM76CHMX-5/NOPB equivalent, key selection considerations include its ±0.5°C accuracy at 25°C, −20°C to +85°C specified operating range, 250 µA typical supply current, SOIC-8 package, and ACPI-compliant dual-threshold interrupt architecture.

Technical Context

The LM76CHMX-5/NOPB integrates a band-gap temperature sensor, 13-bit ADC, and digital comparator logic with user-programmable TLOW, THIGH, and T_CRIT thresholds. Its two-wire I²C slave interface uses hardwired "10010" MSBs plus A0/A1 pins for up to four device addresses on one bus.

It supports both Comparator and Event Interrupt modes via Configuration Register D1, provides 2°C default hysteresis, and includes a 4-fault queue to suppress noise-induced false triggers. Shutdown mode reduces quiescent current to 5 µA while retaining register accessibility.

Key Specifications

Pinout & Package

LM76CHMX-5/NOPB is housed in an 8-pin SOIC package (Package Number D), with exposed pad not present. Pin functions are electrically validated per TI SNIS109E Rev. E.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM76CHMX-5/NOPB, LM75BIMM-5/NOPB offers lower cost but sacrifices accuracy, resolution, and autonomous critical alarm functionality; MAX31820MUA+ provides matching accuracy in a smaller package but replaces I²C with 1-Wire and removes hardware T_CRIT_A assertion - making LM76CHMX-5/NOPB uniquely suited for ACPI-compliant, dual-path thermal safety systems.

Availability

LM76CHMX-5/NOPB is available at Aetrix Electronics and suitable for personal computer thermal management, industrial power supply monitoring, and office equipment protection requiring stable component supply and long-term lifecycle support.

Supply support for LM76CHMX-5/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 headquartered in Dallas, Texas, delivering analog and embedded processing solutions for industrial, automotive, and communications markets since 1930.

The LM76CHMX-5/NOPB belongs to TI's precision analog temperature sensor product line, engineered specifically for ACPI-compliant thermal monitoring and hardware-based critical shutdown in computing and power systems.

FAQ

What is the accuracy specification of the LM76CHMX-5/NOPB across its full operating range?

The LM76CHMX-5/NOPB is specified for ±0.5°C accuracy at +25°C, ±1.5°C over its −20°C to +85°C specified temperature range, and ±1.0°C from +70°C to +100°C. These values are measured at V_S = 5.0 V ±10% and reflect guaranteed limits per TI SNIS109E Rev. E. Accuracy degrades by only 0.08°C per ±1% supply variation, confirming tight voltage sensitivity for stable operation in 5V rail environments.

How does the LM76CHMX-5/NOPB support ACPI-compliant thermal management in PCs?

The LM76CHMX-5/NOPB supports ACPI compliance through its dual open-drain outputs: INT signals window violations (TLOW/THIGH) to the host processor for OS-level thermal policy execution, while T_CRIT_A asserts independently to trigger hardware-level power-down-bypassing software entirely. Its default power-up thresholds (TLOW=10°C, THIGH=64°C, T_CRIT=80°C) and configurable hysteresis align directly with ACPI thermal zone definitions and event reporting requirements.

Can multiple LM76CHMX-5/NOPB sensors share the same I²C bus, and how is addressing managed?

Yes, up to four LM76CHMX-5/NOPB sensors can operate on a single I²C bus. Addressing is controlled by the A0 and A1 pins: each pin accepts TTL logic levels (0 = GND, 1 = +VS), forming the two LSBs of a fixed 7-bit slave address "10010xx". This yields four unique addresses (0x48–0x4B), enabling simultaneous monitoring of multiple thermal zones without bus contention or software arbitration.

What is the function of the fault queue in the LM76CHMX-5/NOPB, and how is it enabled?

The fault queue in the LM76CHMX-5/NOPB requires four consecutive out-of-window temperature readings before asserting INT or T_CRIT_A, preventing false triggers from transient noise or measurement glitches. It is enabled by setting bit D4 (Fault Queue) high in the Configuration Register (address 0x01). The feature is inactive by default (bit = 0) and must be explicitly configured via I²C write to ensure robust operation in electrically noisy PC chassis or industrial enclosures.

Does the LM76CHMX-5/NOPB support shutdown mode, and what happens to its outputs during shutdown?

Yes, the LM76CHMX-5/NOPB supports shutdown mode via bit D0 in the Configuration Register. When activated, supply current drops to ≤5 µA typical, conversions halt, and both INT and T_CRIT_A outputs are reset (de-asserted). The I²C interface remains fully operational, allowing registers to be read or reconfigured without exiting shutdown - enabling ultra-low-power thermal supervision during system sleep states while preserving configuration integrity.