Описание

The TMP451 device is a high-accuracy, low-power remote temperature sensor monitor with a built-in local temperature sensor. The remote temperature sensors are typically low-cost discrete NPN or PNP transistors, or substrate thermal transistors or diodes that are integral parts of microprocessors, microcontrollers, or FPGAs. The temperature is represented as a 12-bit digital code for both the local and remote sensors, giving a resolution of 0.0625°C. The temperature accuracy is ±1°C (maximum) in the typical operating range for the local and the remote temperature sensors. The two-wire serial interface accepts the SMBus communication protocol.
Advanced features such as series resistance cancellation, programmable nonideality factor (ηfactor), programmable offset, programmable temperature limits, and a programmable digital filter are combined to provide a robust thermal monitoring solution with improved accuracy and noise immunity.
The TMP451 device is ideal for high-accuracy temperature measurements in multiple locations and in a variety of automotive subsystems. The device is specified for operation over a supply voltage range of 1.7 V to 3.6 V and a temperature range of–40°C to 125°C.

 

Характеристики

• ±1°C Accuracy for Local and Remote Diode 1 Sensors
• 0.0625°C Resolution for Local and Remote Channels
• 1.7-V to 3.6-V Supply and Logic Voltage Range
• 27-µA Operating Current, 3-µA Shutdown Current
• Series Resistance Cancellation
• η-Factor and Offset Correction
• Programmable Digital Filter
• Diode Fault Detection
• Two-Wire and SMBus™ Serial Interface
• 8-Lead WSON (WDFN) Package

 

Приложения

• Processor and FPGA Temperature Monitoring
• Smart Phones and Tablets
• Servers, Desktops, and Notebooks
• Telecom Equipment and Storage Area Networks (SANs)

 

Обзор

The TMP451 device is a digital temperature sensor that combines a local temperature measurement channel and a remote-junction temperature measurement channel in a single DFN-8 package. The device is two-wire and SMBus-interface compatible, and is specified over a temperature range of–40°C to 125°C. The TMP451 device also contains multiple registers for programming and holding configuration settings, temperature limits, and temperature measurement results.

 

Temperature Measurement Data

The local and remote temperature sensors have a resolution of 12 bits (0.0625°C). Temperature data that result from conversions within the default measurement range are represented in binary form.Any temperature below 0°C results in a data value of 0 (00h). Likewise, temperatures above 127°C result in a value of 127 (7Fh). The device can be set to measure over an extended temperature range by changing bit 2 (RANGE) of configuration register from low to high. The change in measurement range and data format from standard binary to extended binary occurs at the next temperature conversion. For data captured in the extended temperature range configuration, an offset of 64 (40h) is added to the standard binary value. This configuration allows measurement of temperatures as low as–64°C, and as high as 191°C; however, most temperature-sensing diodes only measure with the range of–55°C to 150°C. Additionally, the TMP451 device is specified only for ambient temperatures ranging from–40°C to 125°C; parameters in the Absolute Maximum Ratings table must be observed.

 

Filtering

Remote junction temperature sensors are usually implemented in a noisy environment. Noise is most often created by fast digital signals, and it can corrupt measurements. The TMP451 device has a built-in, 65-kHz filter on the inputs of D+ and D– to minimize the effects of noise. However, a bypass capacitor placed differentially across the inputs of the remote temperature sensor is recommended to make the application more robust against unwanted coupled signals. For this capacitor, select a value of between 100 pF and 1 nF. Some applications attain better overall accuracy with additional series resistance; however, this increased accuracy is application specific. When series resistance is added, the total value should not be greater than 1 kΩ. If filtering is required, suggested component values are 100 pF and 50 Ω on each input; exact values are application-specific.