Texas Instruments LM73C1QDDCRQ1

Overview

LM73C1QDDCRQ1 from Texas Instruments is an AEC-Q100 Grade 1 automotive-qualified digital temperature sensor with 11- to 14-bit programmable resolution, ±1.45°C max accuracy over –10°C to 80°C, and SMBus/I²C-compatible 2-wire interface operating up to 400 kHz - used for real-time die temperature monitoring in engine control units and ADAS sensor modules.

For engineers reviewing the LM73C1QDDCRQ1 datasheet, LM73C1QDDCRQ1 pinout, LM73C1QDDCRQ1 application, or LM73C1QDDCRQ1 equivalent, this page delivers verified technical context, validated pin functions, confirmed automotive-grade thermal specs, and two rigorously cross-checked alternative parts for temperature-sensing subsystems requiring functional compatibility and AEC-Q100 compliance.

Technical Context

The LM73C1QDDCRQ1 integrates a delta-sigma ADC with on-die temperature sensing and a fully compliant SMBus 2.0/I²C slave interface supporting 7-bit addressing (1001100b default for C1 variant), open-drain SMBDAT/SMBCLK with integrated low-pass filtering, and timeout-based bus recovery. It features a dedicated ADDR pin enabling three selectable device addresses per version.

Its functional architecture includes programmable resolution (11–14 bits), shutdown mode with one-shot conversion, ALERT output driven by THIGH/TLOW register comparison, and internal power-on reset with 1 ms typical POR time. All temperature comparisons for ALERT use fixed 11-bit arithmetic regardless of selected resolution.

Key Specifications

Pinout & Package

SOT-23-6 (DDC) package, 2.90 mm × 1.60 mm body size, surface-mount, lead-free, RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM73C1QDDCRQ1, LM73C0QDDCRQ1 offers identical performance with only address variation, while STLM75QDT6F trades resolution, accuracy, and SMBus reliability for lower unit cost in non-automotive contexts.

Availability

LM73C1QDDCRQ1 is available at Aetrix Electronics and suitable for automotive climate control, ADAS sensor modules, infotainment processor thermal management, and HID lamp protection requiring stable component supply across extended production lifecycles.

Supply support for LM73C1QDDCRQ1 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 specializing in analog and embedded processing technologies, with leadership in automotive-grade sensing, power management, and interface solutions.

The LM73-Q1 product line delivers AEC-Q100-qualified digital temperature sensors optimized for real-time thermal monitoring in harsh automotive environments where reliability, precision, and bus robustness are critical.

FAQ

What is the default SMBus address for LM73C1QDDCRQ1?

The LM73C1QDDCRQ1 defaults to SMBus slave address 1001100b (0x4C in hexadecimal) when the ADDR pin is left floating. This address is fixed for the C1 variant and distinct from the C0 variant (1001000b). The LM73C1QDDCRQ1 supports two additional addresses - 1001101b (0x4D) when ADDR = GND, and 1001110b (0x4E) when ADDR = VDD - enabling up to three devices on the same bus without address conflict.

Does LM73C1QDDCRQ1 support I²C clock stretching?

No, LM73C1QDDCRQ1 does not support clock stretching. Its SMBCLK pin is input-only and the device never holds the clock line low to delay communication. This design simplifies timing but requires the host controller to manage transaction pacing. The LM73C1QDDCRQ1 instead implements a 15–45 ms SMBus timeout feature that automatically releases SMBDAT if either bus line is held low too long - a hardware-level safeguard against bus lockup absent clock stretching.

How does ALERT output behavior depend on resolution setting in LM73C1QDDCRQ1?

The ALERT output of LM73C1QDDCRQ1 is unaffected by resolution setting: all THIGH/TLOW comparisons and ALERT assertion/clearing use fixed 11-bit arithmetic regardless of whether 11-, 12-, 13-, or 14-bit mode is selected. This ensures consistent over-temperature response timing and threshold accuracy across all resolution modes. The LM73C1QDDCRQ1's ALERT pin reflects only the result of the 11-bit comparison - not the full-resolution reading stored in the Temperature Register.

What is the maximum recommended pull-up resistance for SMBDAT on LM73C1QDDCRQ1?

The maximum recommended pull-up resistance for SMBDAT on LM73C1QDDCRQ1 is determined by bus capacitance and 400 kHz timing requirements. With 400 pF total load capacitance (including PCB trace and MCU input), TI specifies tF ≤ 250 ns and tSU;DAT ≥ 100 ns. For standard 3.3 V operation, a 2.2 kΩ to 4.7 kΩ external pull-up resistor is typical. Larger values increase rise time and risk violating SMBus timing; smaller values raise static current and may cause self-heating errors in the LM73C1QDDCRQ1's temperature reading.

Can LM73C1QDDCRQ1 operate reliably at 125°C junction temperature?

Yes, LM73C1QDDCRQ1 is qualified for continuous operation at junction temperatures up to +125°C per AEC-Q100 Grade 1 specification. Its accuracy degrades to ±1.8°C at 115–125°C ambient, and thermal resistance (RθJA = 117°C/W) requires appropriate PCB copper area and airflow to maintain safe junction temperature under full load. The LM73C1QDDCRQ1 includes internal power-on reset and timeout recovery specifically validated for sustained high-temperature automotive environments.