The MAX1668/MAX1805 are precise multichannel digital thermometers that report the temperature of all
remote sensors and their own packages. The remote sensors are diode-connected transistors - typically lowcost, easily mounted 2N3904 NPN types - that replace conventional thermistors or thermocouples. Remote accuracy is +-3C for multiple transistor manufacturers, with no calibration needed. The remote channels can also measure the die temperature of other ICs, such as microprocessors, that contain an on-chip, diode-connected transistor. The 2-wire serial interface accepts standard System Management Bus (SMBus) Write Byte, Read Byte, Send Byte, and Receive Byte commands to program the alarm thresholds and to read temperature data. The data format is 7 bits plus sign, with each bit corresponding to 1C, in two's-complement format. The MAX1668/MAX1805 are available in small, 16-pin QSOP surface-mount packages.