NCT80DBR2G ON Semiconductor

NCT80 2 Hardware Monitor with I C Serial Interface The NCT80 is a twowire serially programmable hardware monitor. It can monitor its on chip temperature via its local sensor, 7 analog inputs and measure the speed of two fans. Each of the measured values NCT80 A2 A1 A0 SDA SCL 24 2 3 23 22 ONCHIP 11 GPO TEMPERATURE I2C INTERFACE SENSOR NTEST IN/ 12 21 AIN0 RST IN 20 AIN1 Limit and 19 AIN2 Data Config ATOD ANALOG Registers 10 AIN3 18 Registers INT CONVERTER MUX 17 AIN4 RST OUT/ 13 Interrupt THERM AIN5 16 Control AIN6 15 CI TACH1 Status Register 4 Fan Speed 5 Counter TACH2 NCT80 14 6 1 9 8 7 V GND AGND CI BTI INT IN DD Figure 1. Functional Block Diagram of NCT80 Table 1. PIN FUNCTION DESCRIPTION Pin No. Pin Name Description 1 INT IN Active low digital input. This signal is propagated to the INT output pin of the NCT80. 2 2 SDA I C Serial Bidirectional Data Input/Output. Opendrain pin needs a pullup resistor. 3 SCL Serial Clock Input. Opendrain pin needs a pullup resistor. 4 TACH1 Digital Input. Fan tachometer input to measure speed of Fan. 5 TACH2 Digital Input. Fan tachometer input to measure speed of Fan. 6 BTI Digital Input. Board Temperature Interrupt driven by O.S. outputs of additional temperature sensors such as the NCT75. 7 CI Digital I/O. An active high input from an external latch which captures a Chassis Intrusion event. (Chassis Intrusion) This line can go high without any clamping action, regardless of the powered state of the NCT80 8 GND Power Supply Ground. 9 V Positive Supply Voltage. Bypass to ground with a 0.1 F bypass capacitor. DD 10 INT Digital Output. Open drain Interrupt Request pin. 11 GPO Digital Output. An active low open drain output intended to drive an external Pchannel power MOSFET in order to offer software power control. 12 NTEST IN/RST IN Dual function pin. Active low input that enables NAND Tree Test functionality. Once enabled the part is reset to its power on default. 13 RST OUT/THERM Dual function pin. RST OUT: Active low reset output pin. THERM: Overtemperature shutdown output pin. 14 AGND Analog Ground. 15 AIN6 Analog Input. 0 V to 2.56 V. 16 AIN5 Analog Input. 0 V to 2.56 V. 17 AIN4 Analog Input. 0 V to 2.56 V. 18 AIN3 Analog Input. 0 V to 2.56 V. 19 AIN2 Analog Input. 0 V to 2.56 V. 20 AIN1 Analog Input. 0 V to 2.56 V. 21 AIN0 Analog Input. 0 V to 2.56 V. 2 22 A0/NTEST OUT Dual function pin. Functions as an I C address selection bit. This is the LSB of the address. Pin also functions as an output when performing a NAND test. 2 23 A1 Functions as an I C address selection bit. 2 24 A2 Functions as an I C address selection bit.