REV. C

ADT7463

–47–

Table XXXI. Register 0x73 – Configuration Register 2 (Power-On Default = 0x00)

Bit

Name

R/W*

Description

0

AIN1

Read/Write

AIN1 = 0, Speed of 3-wire fans measured using the TACH output from the fan.

AIN1 = 1, Pin 11 is reconfigured to measure the speed of 2-wire fans using an external

sensing resistor and coupling capacitor. AIN voltage threshold is set via Configuration

Register 4 (Reg. 0x7D).

1

AIN2

Read/Write

AIN2 = 0, Speed of 3-wire fans measured using the TACH output from the fan.

AIN2 = 1, Pin 12 is reconfigured to measure the speed of 2-wire fans using an external

sensing resistor and coupling capacitor. AIN voltage threshold is set via Configuration

Register 4 (Reg. 0x7D).

2

AIN3

Read/Write

AIN3 = 0, Speed of 3-wire fans measured using the TACH output from the fan.

AIN3 = 1, Pin 9 is reconfigured to measure the speed of 2-wire fans using an external

sensing resistor and coupling capacitor. AIN voltage threshold is set via Configuration

Register 4 (Reg. 0x7D).

3

AIN4

Read/Write

AIN4 = 0, Speed of 3-wire fans measured using the TACH output from the fan.

AIN4 = 1, Pin 14 is reconfigured to measure the speed of 2-wire fans using an external

sensing resistor and coupling capacitor. AIN voltage threshold is set via Configuration

Register 4 (Reg. 0x7D).

4

AVG

Read/Write

AVG = 1, Averaging on the temperature and voltage measurements is turned off. This

allows measurements on each channel to be made much faster.

5

ATTN

Read/Write

12 V inputs. The inputs can be used for other functions such as connecting up external

sensors.

6

CONV

Read/Write

CONV = 1, the ADT7463 is put into a single-channel ADC conversion mode. In this

mode, the ADT7463 can be made to read continuously from one input only, e.g.,

Remote 1 Temperature. It is also possible to start ADC conversions using an external

clock on Pin 11 by setting Bit 2 of Test Register 2 (Reg. 0x7F). This mode could be

useful if, for example, users wanted to characterize/profile CPU temperature quickly.

The appropriate ADC channel is selected by writing to Bits <7:5> of TACH1 Min High

Byte Register (0x55).

Bits <7:5> Reg 0x55

Channel Selected

000

2.5 V

001

010

011

5 V

100

12 V

101

Remote 1 Temperature

110

Local Temperature

111

Remote 2 Temperature

7

SHDN

Read/Write

SHDN = 1, ADT7463 goes into shutdown mode. All PWM outputs assert low (or high

depending on state of INV bit) to switch off all fans. The PWM current duty cycle

registers read 0x00 to indicate that the fans are not being driven.

*This register becomes read-only when the Configuration Register 1 Lock bit is set to 1. Any further attempts to write to this register will have no effect.

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