ADM1031

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27

Table 21. Register 0y22 Fan Speed Configuration Register Power−On Default = 55H

Bit

Name

R/W

Description

<3:0>

Normal/Min Spd 1

R/W

This nibble contains the normal speed value for Fan 1. When in automatic fan speed

control mode, this nibble contains the minimum speed at which Fan 1 runs. Default is

0x05 for 33% PWM duty cycle.

<7:4>

Normal/Min Spd 2

R/W

This nibble contains the normal speed value for Fan 2. When in automatic fan speed

control mode, this nibble contains the minimum speed at which Fan 2 runs. Default is

0x05 for 33% PWM duty cycle.

Table 22. Register 0y23 Fan Filter Register Power−On Default = 50H

Bit

Name

R/W

Description

<7>

Spin−Up Disable

R/W

When set to 1, disables fan spin−up.

<6:5>

Ramp Rate

R/W

These bits set the ramp rate. (Default = 31 Hz)

00 = 1

01 = 2

10 = 4 (Default)

11 = 8

<4:2>

ADC Sample Rate

R/W

These bits set the sampling rate for the ADC.

000 = 87.5 Hz

001 = 175 Hz

010 = 350 Hz

011 = 700 Hz

100 = 1.4 kHz (Default)

101 = 2.8 kHz

110 = 5.6 kHz

111 = 11.2 kHz

<1>

Fan 2 Filter En

R/W

This bit enables fan filtering for Fan 2.

<0>

Fan 1 Filter En

R/W

This bit enables fan filtering for Fan 1.

Bit

Name

R/W

Description

<7:3>

R/W

Contains the minimum temperature value for automatic fan speed control based on

increments. Default is 32°C.

00000 = 0°C

00001 = 4°C

00010 = 8°C

00011 = 12°C

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01000 = 32°C (Default)

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11110 = 120°C

11111 = 124°C

<2:0>

R/W

This nibble contains the temperature range value for automatic fan speed control

based on the local temperature readings.

000 = 5°C

001 = 10°C (Default)

010 = 20°C

011 = 40°C

100 = 80°C