The TMP421, TMP422, and TMP423 are remote temperature sensor monitors with a built-in local temperature sensor. The remote temperature sensor diode-connected transistors are typically low-cost, NPN- or PNP-type transistors or diodes that are an integral part of microcontrollers, microprocessors, or FPGAs. Remote accuracy is ±1°C for multiple IC manufacturers, with no calibration needed. The two-wire serial interface accepts SMBus write byte, read byte, send byte, and receive byte commands to configure the device. The TMP421, TMP422, and TMP423 include series resistance cancellation, programmable non-ideality factor, wide remote temperature measurement range (up to +150°C), and diode fault detection. The TMP421, TMP422, and TMP423 are all available in a SOT23-8 package. The TMP421C is also available in a DSBGA (WCSP) package.