Texas Instruments LM70CIMM-3

Overview

LM70CIMM-3 from Texas Instruments is a SPI/MICROWIRE-compatible 10-bit plus sign digital temperature sensor in VSSOP-8 package, delivering 0.25°C resolution over −55°C to +150°C, with 260 μA typical supply current and shutdown mode drawing <12 μA - used for real-time thermal monitoring in disk drive controllers and embedded system management.

For engineers reviewing the LM70CIMM-3 datasheet, LM70CIMM-3 pinout, LM70CIMM-3 application, or LM70CIMM-3 equivalent, this page provides verified technical context, validated pin functions, confirmed accuracy specs across operating ranges, and two field-tested alternative options for thermal sensing in space-constrained industrial and computing systems.

Technical Context

The LM70CIMM-3 integrates a band-gap temperature sensor and ΔΣ ADC, outputting 11-bit two's complement data (1 sign + 10 temperature bits) where 1 LSB = 0.25°C. It operates as a serial bus slave compatible with both SPI and MICROWIRE protocols, using SI/O bidirectional data line, SC clock input, and CS chip select.

Communication requires 32 serial clocks per full cycle: first 16 clocks transmit temperature data (MSB-first), second 16 clocks accept configuration commands - only 00h–7Fh writes enable normal operation, while FFh triggers shutdown and manufacturer ID readback. Internal registers include read-only temperature and ID registers, and write-only configuration register controlling continuous/shutdown modes.

Key Specifications

Pinout & Package

VSSOP-8 package (DGK0008A), 2.9 mm × 3.1 mm × 1.1 mm body, exposed pad not electrically connected, RoHS-compliant with SN lead finish (LM70CIMM-3.A variant), MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6627ASA+ and ADT7301ARMZ, the LM70CIMM-3 offers optimal balance of SPI compatibility, wide temperature range, and proven reliability in cost-sensitive computing and storage applications - making it the preferred choice where 0.25°C resolution and −55°C capability are sufficient and 5V operation is required.

Availability

LM70CIMM-3 is available at Aetrix Electronics and suitable for hard disk drives, industrial PLC cabinets, office printer fuser assemblies, and embedded network switches requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LM70CIMM-3 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 specializing in analog, embedded processing, and connectivity technologies, with over 50 years of innovation in precision sensing and power management ICs.

The LM70 series was designed specifically for embedded thermal monitoring in space-constrained, high-reliability systems - emphasizing SPI simplicity, wide temperature operation, and low-power shutdown for computing, storage, and industrial control applications.

FAQ

What is the maximum operating temperature range of the LM70CIMM-3?

The LM70CIMM-3 is specified to operate from −55°C to +150°C. This full-range performance is validated per TI's production test flow and includes accuracy limits of +3.5°C/−2.0°C at the extremes. The device's thermal resistance (θJA = 200°C/W) assumes mounting on a standard 2 oz copper PCB - actual junction temperature must be calculated using measured ambient and power dissipation to ensure safe operation within this range. LM70CIMM-3 maintains functionality throughout this span without derating.

Does the LM70CIMM-3 require an external crystal or clock source?

No, the LM70CIMM-3 does not require an external crystal or clock source. Its internal ΔΣ ADC and timing circuitry are fully self-contained. The only external timing signal needed is the serial clock (SC) provided by the host microcontroller - which can be generated from any stable digital source (e.g., MCU GPIO timer output). The LM70CIMM-3 derives all internal timing from SC, eliminating BOM cost and board area associated with oscillators or resonators.

How does the shutdown mode of the LM70CIMM-3 function in practice?

In shutdown mode, the LM70CIMM-3 draws ≤12 μA while retaining SPI bus responsiveness. Writing FFh to the configuration register places it in shutdown; subsequent reads return the manufacturer ID (10000001xxxxb) instead of temperature data. The part remains addressable and exits shutdown immediately upon writing 00h–7Fh - enabling rapid wake-and-measure sequences ideal for duty-cycled thermal logging. LM70CIMM-3 does not auto-wake; host control is required for all state transitions.

Can the LM70CIMM-3 be used with a 5V microcontroller SPI interface?

Yes, the LM70CIMM-3 supports 2.65V to 5.5V supply voltage and has Schmitt-triggered inputs rated for V+ × 0.7 V (min) logic high and V+ × 0.3 V (max) logic low - meaning at V+ = 5V, it reliably accepts 3.5V–5.3V as "1" and 0V–1.5V as "0". Its SI/O output drives to 2.4V min (IOH = −400 μA) and 0.4V max (IOL = +2 mA), compatible with 5V CMOS inputs. No level-shifting is required when interfacing LM70CIMM-3 directly to 5V SPI masters.

What is the thermal measurement accuracy of the LM70CIMM-3 at room temperature?

At 25°C ambient, the LM70CIMM-3 exhibits typical accuracy within ±1.0°C, with a guaranteed maximum error of ±2.0°C over −40°C to +85°C. This specification includes contributions from ADC quantization, sensor nonlinearity, and power supply sensitivity (±5% V+ variation). For applications demanding tighter tolerance, the LM70CIMM-3's consistent 0.25°C LSB allows software-based two-point calibration using known reference temperatures - improving effective accuracy to ±0.5°C in controlled environments. LM70CIMM-3 accuracy is not affected by read rate or bus activity.