Texas Instruments LM56CIMMX

Overview

LM56CIMMX from Texas Instruments is a precision dual-output low-power thermostat IC with internal temperature sensing, two open-collector digital outputs (OUT1/OUT2), 1.250V ±1% bandgap reference, and ±3°C trip point accuracy over −40°C to +125°C - used for thermal management in microprocessors, fan control, and industrial process monitoring.

For engineers reviewing the LM56CIMMX datasheet, LM56CIMMX pinout, LM56CIMMX application, or LM56CIMMX equivalent, this page delivers verified specifications, package mapping to VSSOP-8, functional pin roles, real-world thermal trip behavior, and validated alternative parts for thermal protection designs requiring stable hysteresis and low quiescent current (230 μA max).

Technical Context

The LM56CIMMX integrates an internal temperature sensor with +6.20 mV/°C output sensitivity and fixed 5°C typical hysteresis per output, enabling independent high- and low-temperature trip detection via externally set VT1 and VT2 thresholds using three resistors. Its dual comparators operate with 2–8 mV offset error and 1500 Ω max output impedance.

It uses a 1.250V bandgap reference (±1% error) to generate trip voltages; VT1 = 1.250V × R1/(R1+R2+R3), VT2 = 1.250V × (R1+R2)/(R1+R2+R3), with recommended total resistor sum of 27 kΩ to minimize bias current error (≤300 nA). Power supply range is 2.7V–10V, supporting 3.0V and 5V systems.

Key Specifications

Pinout & Package

LM56CIMMX is packaged in an 8-pin VSSOP (DGK) surface-mount package, 3.0 mm × 3.0 mm × 1.1 mm height, with exposed pad for thermal performance and JEDEC MO-187 compliance. Pin 1 index area located at top-left corner with notch marking.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-output thermal protection applications.

Compared with LM56CIMMX, LM56BIMMX/NOPB offers superior trip accuracy without layout or firmware changes, while MAX6505ASA+ trades dual functionality for ultra-low power and smaller size - making LM56CIMMX the optimal balance of dual-threshold capability, accuracy, and power in VSSOP-8.

Availability

LM56CIMMX is available at Aetrix Electronics and suitable for microprocessor thermal management, fan control, and portable battery-powered 3.0V or 5V systems requiring stable component supply and long-term industrial lifecycle support.

Supply support for LM56CIMMX 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 leader delivering analog, embedded processing, and connectivity solutions with emphasis on reliability, precision, and power efficiency.

The LM56 product line was designed specifically for low-power, dual-threshold thermal protection in space-constrained and battery-sensitive applications - integrating sensor, reference, and comparators in one monolithic IC.

FAQ

What is the operating temperature range of the LM56CIMMX?

The LM56CIMMX operates across −40°C to +125°C ambient temperature. Its trip point accuracy is specified as ±3°C maximum over this full range, with improved ±2°C accuracy available in the LM56BIMMX variant. The internal temperature sensor tracks die temperature, and mounting on thermally conductive PCB areas ensures accurate system-level thermal monitoring. All electrical characteristics in the datasheet are validated within this range.

How do I set the two temperature trip points (T1 and T2) for LM56CIMMX?

You set T1 and T2 by connecting three external resistors (R1, R2, R3) to form voltage dividers on VT1 and VT2 pins, referenced to the internal 1.250V VREF. Use VT1 = 1.250V × R1/(R1+R2+R3) and VT2 = 1.250V × (R1+R2)/(R1+R2+R3), with R1+R2+R3 = 27 kΩ recommended to limit comparator bias current error. Then solve for R1, R2, R3 using the target trip voltages derived from VTEMP = (6.20 mV/°C × T) + 395 mV.

Is LM56CIMMX pin-compatible with LM56BIMMX/NOPB?

Yes, LM56CIMMX and LM56BIMMX/NOPB share identical VSSOP-8 (DGK) packaging, pinout, and electrical interface - including V+, GND, VREF, VTEMP, OUT1, OUT2, VT1, and VT2. The only difference is trip point accuracy: LM56BIMMX guarantees ±2°C vs. ±3°C for LM56CIMMX across −40°C to +125°C. No PCB or schematic changes are needed for substitution.

Can LM56CIMMX directly drive a cooling fan?

No, LM56CIMMX cannot directly drive a cooling fan. Both OUT1 and OUT2 are open-collector outputs rated for ≤50 μA sink current and 0.4V max LOW-level voltage at 50 μA - insufficient for typical fan loads (often >10 mA). These outputs must interface with external driver circuitry such as a small-signal NPN transistor, MOSFET, or logic buffer (e.g., ULN2003) to safely control fan power stages.

What is the purpose of the VTEMP pin on LM56CIMMX?

The VTEMP pin outputs an analog voltage proportional to die temperature: VTEMP = (6.20 mV/°C × T) + 395 mV. This allows external verification of temperature readings, calibration against known references, or integration into ADC-based monitoring systems. With 1500 Ω max output impedance, it supports RC filtering (e.g., 1 μF to GND) to suppress noise in electrically noisy environments without significantly affecting thermal response time.