NCT72

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2

Figure 1. Functional Block Diagram

ON-CHIP

TEMPERATURE

SENSOR

ANALOG

MUX

BUSY

A-TO-D

CONVERTER

LOCAL TEMPERATURE

VALUE REGISTER

REMOTE OFFSET

REGISTER

RUN/STANDBY

EXTERNAL DIODE OPEN-CIRCUIT

STATUS REGISTER

INTERRUPT

MASKING

SDATA

SCLK

8

7

ADDRESS POINTER

REGISTER

CONVERSION RATE

REGISTER

LOCAL TEMPERATURE

LOW-LIMIT REGISTER

LOCAL TEMPERATURE

HIGH-LIMIT REGISTER

REMOTE TEMPERATURE

LOW-LIMIT REGISTER

REMOTE TEMPERATURE

HIGH-LIMIT REGISTER

LOCAL THERM

LIMIT REGISTERS

EXTERNAL THERM

LIMIT REGISTERS

CONFIGURATION

REGISTERS

4

6

GND

5

1

NCT72

D+

ALERT/THERM2

THERM

2

D−

3

REMOTE TEMPERATURE

VALUE REGISTER

Table 1. PIN ASSIGNMENT

Pin No.

Mnemonic

Description

1

Positive Supply, 2.8 V to 3.6 V.

2

D+

Positive Connection to Remote Temperature Sensor.

3

D−

Negative Connection to Remote Temperature Sensor.

4

THERM

Open-drain Output. Can be used to turn a fan on/off or throttle a CPU clock in the event of an

overtemperature condition. Requires pullup resistor.

5

GND

Supply Ground Connection.

6

ALERT/THERM2

Open-drain Logic Output Used as Interrupt or SMBus ALERT. This can also be configured as a

second THERM output. Requires pullup resistor.

7

SDATA

Logic Input/Output, SMBus Serial Data. Open-drain Output. Requires pullup resistor.

8

SCLK

Logic Input, SMBus Serial Clock. Requires pullup resistor.

NOTE: The ground slug on 3x3 package can be left unconnected.