REV. C

–50–

ADT7463

Table XXXIX. Register 0x7B – Fan Pulses per Revolution Register (Power-On Default = 0x55)

Bit

Name

R/W

Description

<1:0>

FAN1

Read/Write

Sets number of pulses to be counted when measuring FAN 1 speed. Can be used to

determine fan’s pulses per revolution for unknown fan type.

Pulses Counted

00 = 1

01 = 2 (Default)

10 = 3

11 = 4

<3:2>

FAN2

Read/Write

Sets number of pulses to be counted when measuring FAN 2 speed. Can be used to

determine fan’s pulses per revolution for unknown fan type.

Pulses Counted

00 = 1

01 = 2 (Default)

10 = 3

11 = 4

<5:4>

FAN3

Read/Write

Sets number of pulses to be counted when measuring FAN 3 speed. Can be used to

determine fan’s pulses per revolution for unknown fan type.

Pulses Counted

00 = 1

01 = 2 (Default)

10 = 3

11 = 4

<7:6>

FAN4

Read/Write

Sets number of pulses to be counted when measuring FAN 4 speed. Can be used to

determine fan’s pulses per revolution for unknown fan type.

Pulses Counted

00 = 1

01 = 2 (Default)

10 = 3

11 = 4

Table XL. Register 0x7D – Configuration Register 4 (Power-On Default = 0x00)

Bit

Name

R/W

Description

<0>

AL2.5V

Read/Write

AL2.5V = 1, Pin 22 (2.5V/SMBALERT) is configured as an SMBALERT interrupt

output to indicate out-of-limit error conditions. AL2.5V = 0, Pin 22 (2.5V/SMBALERT)

is configured as a 2.5 V measurement input.

<1>

TH5V

Read/Write

TH5V = 1, Pin 20 (5V/THERM) is configured as THERM pin. For THERM

Monitoring, Bit 1 (THERM Timer) of Configuration Register 3 must also be set.

TH5V = 0, Pin 20 (5V/THERM) is configured as 5 V measurement input.

<3:2>

AINL

Read/Write

These two bits define the input threshold for 2-wire fan speed measurements:

00 = �20 mV

01 = �40 mV

10 = �80 mV

11 = �130 mV

<7:4>

RES

Unused.

*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.

Table XLI. Register 0x7E – Manufacturer’s Test Register 1 (Power-On Default = 0x00)

Bit

Name

Read/Write

Description

<7:0>

Reserved

Read-Only

Manufacturer’s Test Register. These bits are reserved for manufacturer’s test

purposes and should NOT be written to under normal operation.

Table XLII. Register 0x7F – Manufacturer’s Test Register 2 (Power-On Default = 0x00)

Bit

Name

Read/Write

Description

<7:0>

Reserved

Read-Only

Manufacturer’s Test Register. These bits are reserved for manufacturer’s test

purposes and should NOT be written to under normal operation.

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