ADM1031 datasheet(15/32 Pages) AD

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REV. 0

ADM1031

–15–

RELEVANT REGISTERS FOR AUTOMATIC FAN SPEED

CONTROL MODE

<7>

Logic 1 selects Automatic Fan Speed Control, Logic 0

selects software control (Default = 1).

<6:5> 00 = Remote Temp 1 controls Fan 1, Remote Temp 2

controls Fan 2.

01 = Remote Temp 1 controls Fans 1 and 2

10 = Remote Temp 2 controls Fans 1 and 2

11 = Fastest Calculated Speed controls Fans 1 and 2

<2:0> Fan X Spin-Up Time

000 = 200 ms

001 = 400 ms

010 = 600 ms

011 = 800 ms

100 = 1 sec

101 = 2 secs (Default)

110 = 4 secs

111 = 8 secs

<5:3> PWM Frequency Driving the Fan

000 = 11.7 Hz

001 = 15.6 Hz

010 = 23.4 Hz

011 = 31.25 Hz (Default)

100 = 37.5 Hz

101 = 46.9 Hz

110 = 62.5 Hz

111 = 93.5 Hz

<7:6> Speed Range N; defines the lowest fan speed that can be

measured by the device.

00 = 1: Lowest Speed = 2647 RPM

01 = 2: Lowest Speed = 1324 RPM

10 = 4: Lowest Speed = 662 RPM

11 = 8: Lowest Speed = 331 RPM

<3:0> Min Speed: This nibble contains the speed at which the

fan will run when the temperature is at TMIN. The default is

0x05, meaning that the fan will run at 33% duty cycle

when the temperature is at TMIN.

<7:4> Min Speed: Determines the minimum PWM cycle for

Fan 2 in Automatic Fan Speed Control Mode.

<7:3> Local Temperature TMIN. These bits set the temperature

at which the fan will turn on when under Auto Fan Speed

Control. TMIN can be programmed in 4

°C increments.

00000 = 0

°C

00001 = 4

°C

00010 = 8

°C

00011 = 12

°C

01000 = 32

°C (Default)

11110 = 120

°C

11111 = 124

°C

<2:0> Local Temperature TRANGE. This nibble sets the tem-

perature range over which Automatic Fan Speed Control

takes place.

000 = 5

°C

001 = 10

°C

010 = 20

°C

011 = 40

°C

100 = 80

°C

<7:3> Remote Temperature TMIN. Sets the temperature at

which the fan will switch on based on Remote X Tem-

perature Readings.

00000 = 0

°C

00001 = 4

°C

00010 = 8

°C

00011 = 12

°C

01100 = 48

°C

11110 = 120

°C

11111 = 124

°C

<2:0> Remote Temperature TRANGE. This nibble sets the tem-

perature range over which the fan will be controlled

based on Remote Temperature readings.

000 = 5

°C

001 = 10

°C

010 = 20

°C

011 = 40

°C

100 = 80

°C

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