TMP421AQDCNTQ1 - ±1°C Remote/Local Temp Sensor, AEC-Q100 | TI
MPN: TMP421AQDCNTQ1 ✓ Hoạt độngTMP421AQDCNTQ1 Tóm tắt
A remote-junction digital temperature sensor is an integrated transducer that converts a diode-connected transistor's forward-voltage drop into a digital temperature code. Unlike analog thermistors, it applies series-resistance cancellation and a programmable non-ideality factor so that layout series resistance and discrete-transistor beta variation do not degrade accuracy. Within the broader system hierarchy this places the TMP421AQDCNTQ1 at the Sensors > Temperature Sensors layer, used alongside power management ICs, supervisors, and fan controllers.
Key features include a 2.7V to 5.5V supply range, diode-fault detection for open/short conditions, configurable conversion rate, and a high-impedance analog input that ignores parallel paths. The SOT-23-8 footprint integrates into tight PCBs such as M.2 modules, server DIMMs, and battery-pack monitors where board area is constrained.
Typical applications include automotive infotainment SoC thermal monitoring, server/SSD controller die-temperature reading, and battery-pack MOSFET thermistor replacement. When designing, place the TMP421AQDCNTQ1 within 10 cm of the remote diode and route the D+/D- traces as a matched differential pair to preserve ±1°C accuracy; this is the same layout rule TI recommends in the TMP42x-Q1 datasheet.
When designing with this device, ensure the external NPN/PNP is the substrate-diode of the monitored device when possible, since that path has the lowest series resistance and the best matched ideality factor. The remote D+/D- traces should be routed symmetrically, not over a split plane, to avoid leakage-induced offset.
Bộ thay thế dễ dàng lắp đặt cho TMP421AQDCNTQ1 — cùng gói, chân-to-chân tương thích. Các bộ phận yêu cầu hàn PCB bị loại trừ.
TMP421AIDCNR
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
TMP421AQDCNRQ1
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
TMP422AQDCNRQ1
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
TMP423AQDCNRQ1
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
EMC1412-1-ACPC
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
TMP421AQDCNTQ1 Tỷ lệ tối đa & tính chất điện
| Kiểu cảm biến | Digital, Local/Remote |
| Remote Channels | 1 |
| Local Sensor Accuracy (max) | ±1.5 °C |
| Remote Sensor Accuracy (max) | ±1 °C |
| Local Temperature Range | -40 °C to +127 °C |
| Remote Temperature Range | -40 °C to +150 °C |
| Độ phân giải | 12 bit |
| Supply Voltage Range | 2.7 V to 5.5 V |
| Giao diện | I2C / SMBus (2-wire) |
| I2C Address Options | 9 user-selectable |
| Tính năng | Series-resistance cancellation, programmable non-ideality factor, diode fault detection |
| Hộp | SOT-23-8 (DCN) |
| Kiểu lắp đặt | Surface Mount |
| Khoảng nhiệt độ hoạt động | -40 °C to +125 °C |
| Trạng thái RoHS | Compliant |
| Automotive Qualification | AEC-Q100 |
| Lead-Free | Yes |
Cấu hình chân TMP421AQDCNTQ1
| Chân 1 | GND — Ground reference |
| Chân 2 | D+ — Positive connection to remote temperature sensor diode |
| Chân 3 | D- — Negative connection to remote temperature sensor diode |
| Chân 4 | V+ — Positive supply voltage (2.7V to 5.5V) |
| Chân 5 | SDA — Serial data line (SMBus/I2C) |
| Chân 6 | SCL — Serial clock line (SMBus/I2C) |
| Chân 7 | ALERT/THERM — SMBus alert / thermal interrupt output |
| Chân 8 | ADD0 — I2C address select bit 0 |
Ứng dụng tiêu biểu
TMP421AQDCNTQ1 phù hợp cho 6 Áp dụngs: Automotive Infotainment SoC Thermal Monitor, Server SSD Controller Die-Temperature Reading, Battery Pack Cell Temperature Monitoring, FPGA/SoC Module Thermal Sensor, Industrial Router / Switch Board Monitor, Automotive LED Headlamp Thermal Management.
Automotive Infotainment SoC Thermal Monitor
The TMP421AQDCNTQ1 is a strong fit for monitoring the junction temperature of an automotive infotainment SoC because its ±1°C remote accuracy and AEC-Q100 qualification meet cabin-temperature reliability targets across a range from -40°C to +85°C. The D+/D- inputs sense the SoC substrate diode at 1.5 ms conversion time, returning a 12-bit code over the SMBus interface to the host MCU. Because of the device's series-resistance cancellation, designers can route the D+/D- pair across a 5-10 cm PCB trace without losing accuracy, which is critical when the SoC sits behind a shielding can. Use this part over a thermistor because it eliminates analog-to-digital conversion overhead in the host firmware.
Được đề xuất
Server SSD Controller Die-Temperature Reading
In M.2 NVMe SSD designs the TMP421AQDCNTQ1 monitors the controller die and the NAND package temperature, feeding the thermal-throttling state machine required by the NVMe spec. The remote-diode input handles up to +150°C, well above the +125°C controller thermal-shutdown trip, while the 2.7V to 5.5V supply integrates with the 3.3V rail common in storage designs. Its 9 user-selectable I2C addresses allow up to nine SSDs on a single bus, useful in dense server backplanes. The device's diode-fault detection flags open/short conditions so the controller can fail-safe rather than report an erroneous 0°C code.
Được đề xuất
Battery Pack Cell Temperature Monitoring
The TMP421AQDCNTQ1 supports battery-pack designs that use a small NPN transistor (such as MMBT3904) as a remote temperature sensor on each cell or MOSFET heatsink. Its 12-bit resolution provides 0.0625°C LSB resolution, allowing the BMS to detect early thermal-runaway events and trigger balancing. The AEC-Q100 grade matches the automotive battery-management requirements, and the 2.7V-5.5V supply aligns with the 3.3V LDO rail typical in 12V/48V systems. Series-resistance cancellation tolerates the long harness between the cells and the BMS board, while diode-fault detection alerts the BMS to a disconnected sense transistor.
Được đề xuất
FPGA/SoC Module Thermal Sensor
The TMP421AQDCNTQ1 reads the substrate diode of an FPGA or high-performance SoC on a system-on-module and reports temperature to the carrier board MCU. The local sensor also measures the module PCB itself, which is useful for detecting cooling-fail conditions before the SoC trips its own thermal diode. Its small SOT-23-8 footprint fits easily beneath BGA packages, and the SMBus interface is already implemented in Linux kernels as a generic hwmon driver, simplifying firmware bring-up. Compared with a thermistor string, this IC cuts calibration time and BOM count.
Được đề xuất
Industrial Router / Switch Board Monitor
Industrial routers and switches use the TMP421AQDCNTQ1 to monitor the switch-SoC die temperature and the SFP cage ambient, supporting NEBS thermal-margin reporting required by telecom operators. Its wide -40°C to +125°C operating range covers outdoor cabinet environments, and the 5.5V maximum supply tolerates the loosely-regulated 5V rail found in PoE-powered designs. With 9 I2C addresses and diode-fault detection, a single controller bus can monitor multiple line cards. Compared with NTC thermistors, the digital output eliminates analog calibration in production.
Được đề xuất
Automotive LED Headlamp Thermal Management
High-power automotive LED headlamps generate substantial heat that must be monitored to drive the LED driver's thermal-foldback loop. The TMP421AQDCNTQ1 reads a remote diode placed on the LED PCB heatsink with ±1°C accuracy, enabling the driver IC to dim the LEDs before they exceed their junction-temperature rating. Its AEC-Q100 grade matches automotive headlamp requirements, and the SMBus interface is widely supported by automotive LED-driver ICs. The 2.7V-5.5V supply aligns with the 5V or 3.3V rails available in headlamp modules.
Được đề xuất
Tóm tắt các sản phẩm được đề xuất
Dữ liệu tham khảo kỹ thuật cho TMP421AQDCNTQ1 — so sánh, hướng dẫn thiết kế và thông tin tuân thủ.
Hướng dẫn chọn lựa
So sánh với các sản phẩm thay thế
| Tham số | Sản phẩm này | TMP421AIDCNR | TMP421AQDCNRQ1 | TMP422AQDCNRQ1 | EMC1412-1-ACPC |
|---|---|---|---|---|---|
| Package | SOT-23-8 (DCN) | SOT-23-8 (DCN) - same | SOT-23-8 (DCN) - same | SOT-23-8 (DCN) - same | SOT-23-8 - same |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Microchip Technology |
| Remote Channels | 1 | 1 | 1 | 2 | 1 |
| Remote Accuracy (max) | ±1 °C | ±2.5 °C | ±1 °C | ±1 °C | ±1 °C |
| Supply Voltage Range | 2.7 V to 5.5 V | 2.7 V to 5.5 V | 2.7 V to 5.5 V | 2.7 V to 5.5 V | 3.0 V to 3.6 V |
| Resolution | 12 bit | 12 bit | 12 bit | 12 bit | 11 bit |
| Diode Fault Detection | Yes | Yes | Yes | Yes | Yes |
| Interface | I2C / SMBus | I2C / SMBus | I2C / SMBus | I2C / SMBus | I2C / SMBus |
Bảo phân biệt quan trọng
- Tighter ±1°C remote accuracy vs industrial version (vsTMP421AIDCNR)
- Pin-to-pin compatible with the two/three-channel siblings (vsTMP422AQDCNRQ1 / TMP423AQDCNRQ1)
- 9 user-selectable I2C addresses for multi-device buses (vsEMC1412-1-ACPC)
Ghi chú thiết kế
Route the D+ and D- traces as a matched differential pair from the TMP421AQDCNTQ1 to the remote diode, keeping the pair within 10 cm and avoiding splits in the ground plane. TI's TMP42x-Q1 datasheet recommends keeping a ground guard trace between D+ and D- to reject leakage currents that would otherwise add 1-2°C of offset error at high temperatures.
Program the non-ideality factor register to match the actual diode in use (typical CPUs: 1.008, small-signal transistors like MMBT3904: 1.010-1.020). Forgetting this register defaults to a generic 1.010 and adds up to 0.5°C error. The TMP421 also requires the series-resistance-cancellation bit to be enabled whenever the layout adds more than 10 ohm of trace resistance.
The SOT-23-8 package has a theta_JA around 200-250 C/W, but the device itself dissipates only a few milliwatts - so the package thermal resistance is rarely the limit. The real thermal limit is the remote diode's self-heating; avoid placing the sense transistor in a region where nearby power components raise its temperature above the die being measured.
Place a 10 nF ceramic bypass capacitor directly at the V+ pin (within 2 mm) and a 100 nF capacitor at the SMBus pull-up rail. The TMP421's SDA/SCL lines tolerate 5V pull-ups even when V+ is 3.3V, but only when the device's maximum ratings are respected - never pull SDA/SCL above 5.5V.
The TMP421AQDCNTQ1 draws around 0.5 mA during conversion and drops to ~10 uA in standby, so a typical always-on ECU sub-system can power it from a low-quiescent LDO. Disable the conversion loop in software between readings to enter the lower-power standby state described in the TMP42x-Q1 datasheet power-management section.
Thông tin tuân thủ
AEC-Q100 qualified per the TMP42x-Q1 datasheet 'Q1' suffix designation. RoHS and REACH compliance stated on the TI.com product page. Halogen-free status not explicitly stated in the provided data.
