19-1836; Rev 2; 1/02
1°C Accurate Remote/Local Temperature Sensor with SMBus Serial Interface
General Description
The i...
19-1836; Rev 2; 1/02
1°C Accurate Remote/Local Temperature Sensor with SMBus Serial Interface
General Description
The is a precise digital thermometer that reports the temperature of both a remote P-N junction and its own die. The remote junction can be a diode-connected
transistor—typically a low-cost, easily mounted 2N3904
NPN type or 2N3906
PNP type—that replaces conventional thermistors or thermocouples. Remote accuracy is ±1°C for multiple
transistor manufacturers, with no calibration needed. The remote junction can also be a common-collector
PNP, such as a substrate
PNP of a microprocessor (µP). The 2-wire serial interface accepts standard System Management Bus (SMBus)TM, Write Byte, Read Byte, Send Byte, and Receive Byte commands to program the alarm thresholds and to read temperature data. Measurements can be done automatically and autonomously, with the conversion rate programmed by the user, or programmed to operate in a single-shot mode. The adjustable conversion rate allows the user to optimize supply current and temperature update rate to match system needs. When the conversion rate is faster than 1Hz, the conversion results are available as a 7-bitplus-sign byte with a 1°C LSB. When the conversion rate is 1Hz or slower, the MAX6654 enters the extended mode. In this mode, 3 additional bits of temperature data are available in the extended resolution register, providing 10-bit-plus-sign resolution with a 0.125°C LSB. Single-shot conversions also have 0.125°C per ...