Texas Instruments LM71CIMF/NOPB

Overview

LM71CIMF/NOPB from Texas Instruments is a 14-bit delta-sigma digital temperature sensor with SPI/MICROWIRE-compatible three-wire serial interface, operating from −40°C to +150°C with ±1.5°C max accuracy over −10°C to +65°C and 31.25 m°C resolution. It delivers 300 µA typical supply current at 2.65V–5.5V supply and is housed in a 5-pin SOT-23 (DBV) package for thermal monitoring in space-constrained embedded systems.

For engineers reviewing the LM71CIMF/NOPB datasheet, LM71CIMF/NOPB pinout, LM71CIMF/NOPB application, or LM71CIMF/NOPB equivalent, key selection considerations include its 14-bit two's complement output format, shutdown/continuous conversion control via 8-bit register write, guaranteed operation across automotive-grade temperature extremes, and compatibility with microcontrollers lacking dedicated temperature interfaces.

Technical Context

The LM71CIMF/NOPB integrates a precision bandgap temperature sensor core with a 14-bit delta-sigma ADC delivering 0.03125°C LSB resolution. Its serial interface operates as a slave device with chip-select (CS), serial clock (SC), and bidirectional SI/O lines - data is clocked out on SC falling edge and sampled on rising edge, supporting full-duplex 32-clock frame transfers.

Internal register architecture includes read-only temperature and manufacturer ID registers plus a write-only configuration register that accepts only 0x00 (continuous mode) or 0xFF (shutdown mode). Power-up defaults to continuous conversion, and first valid reading requires ≥270 ms after power-on reset.

Key Specifications

Pinout & Package

LM71CIMF/NOPB uses the 5-pin SOT-23 (DBV) package with 1.45 mm max height, optimized for PCB area efficiency and thermal coupling to board traces. Pin 1 (CS) is located in quadrant Q3 per tape-and-reel orientation standard.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM71CIMF/NOPB, LM71CIMFX/NOPB offers identical functionality with assured long-term supply and RoHS compliance, while MAX31820 trades interface simplicity and parasitic power capability for reduced resolution and longer conversion latency - making it unsuitable for high-speed thermal loop closure.

Availability

LM71CIMF/NOPB is available at Aetrix Electronics and suitable for system thermal management, personal computers, and disk drives requiring stable component supply despite its obsolete status - we maintain legacy inventory with full traceability and documentation support.

Supply support for LM71CIMF/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 leader specializing in analog and embedded processing technologies, with over 90 years of innovation in precision sensing, power management, and signal chain solutions.

The LM71 product line was designed specifically for high-accuracy, low-power digital temperature measurement in space-constrained industrial and automotive applications - emphasizing robust serial communication, wide operating range, and minimal external component count.

FAQ

What is the operating temperature range of the LM71CIMF/NOPB?

The LM71CIMF/NOPB operates from −40°C to +150°C. This full-range specification ensures reliable performance in harsh environments such as automotive engine bays and industrial motor controllers. The device maintains ±1.5°C max accuracy between −10°C and +65°C, and +3/−2°C max accuracy across the entire −40°C to +150°C span. Its thermal design leverages the SOT-23 package pins as primary heat conduction paths to the PCB.

Does the LM71CIMF/NOPB support SPI or MICROWIRE protocol exclusively?

The LM71CIMF/NOPB supports both SPI and MICROWIRE protocols through its three-wire serial interface (CS, SC, SI/O). It functions as a slave device with data clocked out on the falling edge of SC and sampled on the rising edge. A complete transaction requires 32 clock cycles - 16 for transmit (temperature or ID data) and 16 for receive (mode control). No protocol selection jumpers or configuration bits are needed; compatibility is inherent in the timing and framing.

How does the LM71CIMF/NOPB achieve its 0.03125°C temperature resolution?

The LM71CIMF/NOPB achieves 0.03125°C resolution via a 14-bit delta-sigma analog-to-digital converter with two's complement output coding. Each LSB corresponds to exactly 0.03125°C, enabling precise thermal trending - for example, +25°C maps to 0x0C83 and −25°C to 0xF383. This resolution is fixed and does not vary with temperature or supply voltage, as confirmed in the device's transfer function and electrical characteristics tables.

What is the supply current consumption of the LM71CIMF/NOPB in active and shutdown modes?

In active continuous conversion mode, the LM71CIMF/NOPB draws 300 µA typical and 550 µA maximum supply current. In shutdown mode - activated by writing 0xFF to the configuration register - quiescent current drops below 1 µA, verified by leakage measurements in the datasheet's TRI-STATE output section. This ultra-low shutdown current enables battery-powered applications where periodic wake-up sensing is required without significant energy drain.

Can the LM71CIMF/NOPB be used as a drop-in replacement for the LM71CIMFX/NOPB?

Yes, the LM71CIMF/NOPB is pin-compatible and functionally identical to the LM71CIMFX/NOPB, sharing the same SOT-23 (DBV) package, pinout, electrical specifications, and timing behavior. The only differences are RoHS compliance (LM71CIMFX/NOPB has Sn lead finish) and product status (LM71CIMF/NOPB is obsolete while LM71CIMFX/NOPB is active). For legacy repair or continuity builds, LM71CIMF/NOPB remains fully interoperable with LM71CIMFX/NOPB hardware and firmware.