The NCT72 is a dual-channel digital thermometer and undertemperature/overtemperature alarm, intended for use in PCs and thermal management systems. It is pin and register compatible with the NCT1008 but the NCT72 allows the user to pull the /ALERT pin to 1.8V without increasin the device Idd. A feature of the NCT72 is series resistance cancellation, where up to 1.5 kΩ (typical) of resistance in series with the temperature monitoring diode can be automatically cancelled from the temperature result, allowing noise filtering. The NCT72 has a configurable /ALERT output and an extended, switchable temperature measurement range. The NCT72 can measure the temperature of a remote thermal diode accurate to ±1°C and the ambient temperature accurate to ±3°C. The temperature measurement range defaults to 0°C to +127°C, compatible with the NCT1008, but it can be switched to a wider measurement range of -64°C to +191°C. The NCT72 communicates over a 2-wire serial interface, compatible with system management bus (SMBus/I
C) standards. The default SMBus/I
C address of the NCT72 is 0x4C. An NCT72D is available with an SMBus/I
C address of 0x4D. This is useful if more than one NCT72 is used on the same SMBus/I
C. An /ALERT output signals when the on-chip or remote temperature is out of range. The /THERM output is a comparator output that allows on/off control of a cooling fan. The /ALERT output can be reconfigured as a second /THERM output, if required.

• On-Chip and Remote Temperature Sensor
• 0.25°C Resolution/1°C Accuracy on Remote Channel
• 1°C Resolution/1°C Accuracy on Local Channel
• Series Resistance Cancellation up to 1.5 kΩ
• Extended, Switchable Temperature Measurement Range 0°C to +127°C (Default) or -64°C to +191°C
• Pin and Register Compatible with NCT1008
• Remote /THERM limit of 108°C
• 2-Wire SMBus/I
• C Serial Interface with SMBus Alert Support
• Programmable Over/Undertemperature Limits
• Offset Registers for System Calibration
• Up to Two Overtemperature Fail-Safe /THERM Outputs
• 240 µA Operating Current, 5 µA Standby Current
• Compatible with 1.8 V Logic