The LM95221 is a dual remote diode temperature sensor in an 8-lead VSSOP package. The 2-wire serial interface of the LM95221 is compatible with SMBus 2.0. The LM95221 can sense three temperature zones, it can measure the temperature of its own die as well as two diode connected transistors. The diode connected transistors can be a thermal diode as found in Pentium and AMD processors or can simply be a diode connected MMBT3904 transistor. The LM95221 resolution format for remote temperature readings can be programmed to be 10-bits plus sign or 11-bits unsigned. In the unsigned mode the LM95221 remote diode readings can resolve temperatures above 127°C. Local temperature readings have a resolution of 9-bits plus sign.
The temperature of any ASIC can be accurately determined using the LM95221 as long as a dedicated diode (semiconductor junction) is available on the target die. The LM95221 remote sensor accuracy of ±1°C is factory trimmed for a series resistance of 2.7 ohms and 1.008 non-ideality factor.
