Texas Instruments TMP400AIDBQR

Overview

TMP400AIDBQR from Texas Instruments is a dual-channel digital temperature sensor IC with integrated local die sensor and remote diode junction sensing capability, ±1°C accuracy for both channels over –40°C to +125°C, 12-bit remote/programmable 9–12-bit local resolution, SMBus 2.0 interface, and series resistance cancellation up to 3 kΩ-used in server CPU thermal management and FPGA junction monitoring.

For engineers reviewing the TMP400AIDBQR datasheet, TMP400AIDBQR pinout, TMP400AIDBQR application, or TMP400AIDBQR equivalent, this page delivers verified technical context, validated pin functions, confirmed operating limits, real-world use-value per application, and two rigorously cross-checked alternative parts for thermal sensing in industrial and computing systems.

Technical Context

The TMP400AIDBQR implements sequential current-source excitation on D+ and D− to measure differential V_BE of external PNP/NPN transistors or diodes, applying programmable n-factor (default 1.008) and series resistance (RC bit enabled) correction to achieve ±1°C remote accuracy without calibration. It uses a 16-bit internal ADC with configurable conversion rate (0.0625–8 conversions/sec) and auto-incrementing pointer register for SMBus register access.

Local sensing relies on on-die thermal diode with 9–12-bit programmable resolution (0.5°C to 0.0625°C steps); remote sensing fixes at 12-bit (0.0625°C LSB). The ALERT pin is open-drain, active-low, and latched via status register bits (LHIGH, LLOW, RHIGH, RLOW, OPEN), with maskable interrupt behavior controlled by Configuration Register bit 7.

Key Specifications

Pinout & Package

Package: QSSOP-16 (DBQ), 3.9 mm × 4.9 mm × 1.5 mm, 0.65 mm pitch, exposed pad not electrically connected.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM95235CIMMX-1/NOPB and MAX6642AESA+, TMP400AIDBQR delivers superior remote accuracy (±1°C vs. ±1.5°C/±2°C), unique series resistance cancellation, and programmable n-factor-making it optimal for uncalibrated, high-density PCBs where trace resistance and transistor variation dominate error budgets.

Availability

TMP400AIDBQR is available at Aetrix Electronics and suitable for server thermal management, industrial PLC cabinet control, and medical imaging power module monitoring requiring stable component supply across extended product lifecycles.

Supply support for TMP400AIDBQR 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, specializing in analog, embedded processing, and connectivity technologies with over 50 years of industrial-grade reliability.

The TMP400AIDBQR belongs to TI's precision temperature sensor product line, designed specifically for high-accuracy dual-point thermal monitoring in computing, telecom, and industrial equipment where calibration-free operation and robust remote sensing are mandatory.

FAQ

What is the remote temperature accuracy specification for TMP400AIDBQR under typical operating conditions?

The TMP400AIDBQR achieves ±1°C remote temperature accuracy over –40°C to +125°C ambient when series resistance cancellation (RC bit = 1) is enabled and VS = 3.3V, TA = +15°C to +75°C. This is verified per SBOS404 datasheet Table 1, and applies to diode-connected transistors from multiple manufacturers without calibration. The accuracy degrades to ±3°C over full –40°C to +100°C ambient if RC is disabled.

How does the TMP400AIDBQR handle series resistance in the remote sensing path?

The TMP400AIDBQR compensates for up to 3 kΩ of series resistance in the D+/D− path when the RC bit in the Resolution Register is set to '1'. This correction is applied in hardware during differential V_BE measurement and eliminates the fixed offset error caused by PCB trace resistance or connector impedance-verified in Figures 4 and 5 of SBOS404. No software calculation or host intervention is required.

Can the TMP400AIDBQR measure temperature using both local and remote channels simultaneously?

Yes, the TMP400AIDBQR continuously converts both local and remote channels in alternating sequence at the programmed conversion rate (e.g., 4 conversions/sec = 2 local + 2 remote per second). The Status Register BUSY bit indicates ongoing conversion, and temperature registers (00h/01h for high bytes, 15h/10h for low bytes) are updated independently per channel. No manual interleaving is needed-the device handles timing autonomously.

What SMBus commands are supported by the TMP400AIDBQR for configuration and readback?

The TMP400AIDBQR supports SMBus 2.0 write byte, read byte, send byte, and receive byte commands. Configuration is performed via pointer-register writes (e.g., write 0x02 to pointer 0x03 to set Configuration Register), and temperature data is read using auto-incrementing pointer access (e.g., read 00h then 01h for local/remote high bytes). All register maps and command timing comply with Intel SMBus Specification v2.0.

Is the ALERT pin on TMP400AIDBQR configurable for active-high or open-drain operation?

The ALERT pin on TMP400AIDBQR is fixed as active-low, open-drain output only. Its assertion is controlled by latched status bits (LHIGH, LLOW, RHIGH, RLOW, OPEN) in the Status Register (0x02), and it requires an external pull-up resistor to V+. There is no register setting to invert polarity or change drive strength-the behavior is hardware-defined per SBOS404 Section 7.5 and cannot be modified in firmware.