Texas Instruments LM86CIMM/NOPB

Overview

LM86CIMM/NOPB from Texas Instruments is an 11-bit remote diode and local digital temperature sensor with SMBus 2.0 interface, ±0.75°C remote accuracy at 30°C–50°C ambient and 60°C–100°C remote junction, 0.125°C remote resolution, and dual alert outputs (ALERT and T_CRIT_A) for thermal management in laptop and server CPU subsystems.

For engineers reviewing the LM86CIMM/NOPB datasheet, LM86CIMM/NOPB pinout, LM86CIMM/NOPB application, or LM86CIMM/NOPB equivalent, key selection considerations include remote diode nonideality compensation via offset register, SMBus timeout support, open-drain ALERT/T_CRIT_A behavior under interrupt vs. comparator modes, and compatibility with Pentium III–class thermal diodes.

Technical Context

The LM86CIMM/NOPB implements a delta-V_BE sensing architecture with separate 10-bit-plus-sign ADC paths for local die and remote diode junctions. Its digital comparators independently monitor local/remote temperatures against programmable HIGH, LOW, and T_CRIT registers, driving two dedicated open-drain outputs with distinct hysteresis and reset logic.

It supports three ALERT operating modes-temperature comparator, interrupt flag, and SMBus ARA protocol-with configuration controlled by the FILTER and ALERT CONFIGURE register (0xBF). The T_CRIT_A output operates as a true hardware comparator with hysteresis set via the TH register, independent of software polling.

Key Specifications

Pinout & Package

LM86CIMM/NOPB is housed in an 8-pin VSSOP package (DGK suffix), measuring 3.0 mm × 3.0 mm × 1.0 mm, with exposed thermal pad for enhanced heat dissipation in thermally constrained layouts.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar remote/local temperature sensing applications.

Compared with ADM1032ARQZ and MAX6657ESA+, LM86CIMM/NOPB provides superior remote accuracy (±0.75°C vs. ±1.0/±1.5°C), dedicated T_CRIT_A hardware shutdown path, and robust diode fault detection - making it preferred for mission-critical thermal safety in compute platforms.

Availability

LM86CIMM/NOPB is available at Aetrix Electronics and suitable for laptop thermal management, server blade monitoring, workstation GPU cooling, and industrial embedded controller applications requiring stable component supply and long-term lifecycle support.

Supply support for LM86CIMM/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.

The LM86CIMM/NOPB belongs to TI's precision analog temperature sensor product line, designed specifically for high-accuracy remote diode monitoring in computing platforms where thermal reliability directly impacts system uptime and performance.

FAQ

What is the remote temperature accuracy specification for LM86CIMM/NOPB at typical CPU operating conditions?

The LM86CIMM/NOPB achieves ±0.75°C maximum remote temperature accuracy when ambient temperature is 30°C and remote diode junction temperature is 80°C - matching the thermal operating point of mobile Pentium III and later CPUs with 1.008 nonideality factor. This accuracy is factory-trimmed and does not require end-user calibration. At wider ambient/junction ranges (0°C–85°C / 25°C–125°C), accuracy degrades to ±3.0°C max, as documented in the SNIS114E datasheet.

How does the LM86CIMM/NOPB handle faulty or disconnected remote diodes?

The LM86CIMM/NOPB includes dedicated diode fault detection circuitry that monitors the D+ pin. If D+ is shorted to VDD or left floating, the device loads +127°C into the Remote Temperature High Byte (RTHB) register, sets the OPEN bit (D2) in the Status Register, and reports RT=+127°C. If D+ is shorted to GND or D−, it loads −128°C without setting OPEN. This behavior enables firmware to distinguish between open-circuit and short-circuit faults - a capability not present in ADM1032ARQZ or MAX6657ESA+.

Can LM86CIMM/NOPB operate in SMBus Alert Response Address (ARA) mode, and what configuration is required?

Yes, LM86CIMM/NOPB fully supports SMBus 2.0 ARA protocol. To enable ARA response, bit D0 of the FILTER and ALERT CONFIGURE register (0xBF) must be cleared (0), and the ALERT mask bit (D7 of Configuration register 0x09) must be enabled. Upon receiving an ARA command (0x0C), the LM86CIMM/NOPB transmits its fixed 7-bit slave address (1001100b = 0x4C), then disables its ALERT output by setting the ALERT mask bit - preventing bus lockup. This behavior complies strictly with SMBus 2.0 specification Section 5.3.3.

What is the function of the T_CRIT_A output on LM86CIMM/NOPB, and how does it differ from the ALERT output?

The T_CRIT_A output on LM86CIMM/NOPB is a dedicated, active-low open-drain hardware comparator that asserts whenever either local or remote temperature exceeds its respective T_CRIT register value. Unlike ALERT, T_CRIT_A has built-in hysteresis controlled by the TH register and resets only when temperature falls below (T_CRIT − TH). It operates independently of software polling or SMBus activity - making it suitable for direct connection to power supply shutdown controllers or FPGA hard-wired reset logic in safety-critical thermal protection schemes.

Does LM86CIMM/NOPB support multiple conversion rates, and how does this affect power consumption?

Yes, LM86CIMM/NOPB supports programmable conversion rates via the Conversion Rate Register (0x04). Default is 16 conversions/sec (62.5 ms period), but rates from 0.25 Hz to 16 Hz are selectable. Supply current scales inversely with rate: 0.8 mA typical at 16 Hz, dropping to 315 µA in Shutdown mode. Figure 3 in SNIS114E shows current vs. rate - e.g., at 1 Hz, current is ~120 µA. This allows trade-offs between thermal responsiveness and self-heating error in space-constrained applications.