Texas Instruments LM71QCIMFX/NOPB

Overview

LM71QCIMFX/NOPB from Texas Instruments is an automotive-grade (AEC-Q100 Grade 0), low-power, 14-bit delta-sigma digital temperature sensor with SPI/MICROWIRE 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 precise die-temperature measurement for thermal monitoring in engine control units and powertrain modules.

For engineers reviewing the LM71QCIMFX/NOPB datasheet, LM71QCIMFX/NOPB pinout, LM71QCIMFX/NOPB application, or LM71QCIMFX/NOPB equivalent, key selection considerations include its SOT-23-5 automotive qualification, 2.65V–5.5V supply range, 300 µA typical quiescent current, 270 ms max conversion time, and compatibility with microcontroller SPI peripherals requiring minimal GPIO overhead.

Technical Context

The LM71QCIMFX/NOPB integrates a precision bandgap temperature sensor core with a 13-bit plus sign delta-sigma ADC (14-bit two's complement output), delivering 0.03125°C LSB resolution. Its serial interface operates in SPI or MICROWIRE mode using three wires: CS, SC (Schmitt-trigger clock), and bidirectional SI/O.

Internal registers include read-only temperature and manufacturer ID registers, plus a write-only configuration register controlling shutdown vs. continuous conversion modes. The device powers up in continuous conversion mode and requires ≥270 ms after power-on before first valid temperature read.

Key Specifications

Pinout & Package

LM71QCIMFX/NOPB uses the 5-pin SOT-23 (DBV) package, 2.9 mm × 1.6 mm × 1.45 mm, with exposed pad not electrically connected. Thermal resistance θ_JA = 250°C/W on 2 oz copper PCB.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM71CIMFX/NOPB, the LM71QCIMFX/NOPB adds AEC-Q100 Grade 0 qualification and extended reliability screening but shares identical pinout, interface, and core specifications; MAX31855KASA+ serves a fundamentally different sensing architecture and cannot substitute without hardware redesign.

Availability

LM71QCIMFX/NOPB is available at Aetrix Electronics and suitable for automotive powertrain control, electric vehicle onboard chargers, and ADAS domain controllers requiring stable component supply across multi-year production programs.

Supply support for LM71QCIMFX/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, designing and manufacturing analog ICs, embedded processors, and connectivity solutions for industrial, automotive, and consumer markets.

The LM71 product line delivers high-accuracy, low-power digital temperature sensors optimized for automotive thermal management systems where AEC-Q100 compliance, wide operating range, and SPI simplicity are critical design requirements.

FAQ

What is the AEC-Q100 qualification grade for LM71QCIMFX/NOPB?

The LM71QCIMFX/NOPB is AEC-Q100 Grade 0 qualified, meaning it is tested and certified for operation from −40°C to +150°C ambient temperature and meets stringent automotive reliability standards including HTOL, TC, and ESD testing. This makes LM71QCIMFX/NOPB suitable for engine control, transmission, and powertrain applications where failure is not acceptable.

Does LM71QCIMFX/NOPB support both SPI and MICROWIRE protocols?

Yes, LM71QCIMFX/NOPB supports both SPI and MICROWIRE-compatible serial interfaces using the same three-wire connection (CS, SC, SI/O). Data is clocked out on the falling edge of SC and sampled on the rising edge, matching standard SPI Mode 0 timing. No configuration register setting is required to select between protocols - compatibility is inherent in the physical layer design of LM71QCIMFX/NOPB.

What is the minimum delay required after power-up before reading valid temperature data from LM71QCIMFX/NOPB?

LM71QCIMFX/NOPB requires at least 270 ms after power-on before the first temperature read returns a valid value. This is due to internal oscillator stabilization and ADC initialization. Subsequent reads must also be spaced ≥270 ms apart to ensure full conversion completion. This timing requirement is explicitly defined in the LM71QCIMFX/NOPB datasheet and applies regardless of supply voltage or temperature.

How does the LM71QCIMFX/NOPB temperature resolution translate to practical measurement capability?

LM71QCIMFX/NOPB provides 14-bit two's complement output with 0.03125°C per LSB resolution. This means it can detect temperature changes as small as 31.25 m°C - sufficient to resolve thermal gradients across PCB traces or identify early-stage thermal drift in power semiconductors. The resolution is fixed and independent of temperature range, enabling consistent precision from −40°C to +150°C.

Can LM71QCIMFX/NOPB be used in shutdown mode while maintaining communication capability?

Yes, LM71QCIMFX/NOPB remains fully responsive to SPI commands in shutdown mode: CS can be asserted, and the device will output its Manufacturer/Device ID (0x800F) on SI/O. Shutdown reduces quiescent current to <1 µA while preserving bus interface functionality - allowing host firmware to verify presence and identity without waking the sensor core, which is essential for low-power automotive wake-on-temperature architectures using LM71QCIMFX/NOPB.