ADT7490ARQZ-R7 datasheet(59/75 Pages) ONSEMI

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ADT7490

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Table 50. Register 0x62 — Enhanced Acoustics Register 1 (Power−On Default = 0x00)

Bit No.

Mnemonic

R/W (Note 1)

Description

[2:0]

ACOU

(Note 2)

R/W

Assuming that PWMx is associated with the Remote 1 temperature channel, these bits define

the maximum rate of change of the PWMx output for Remote 1 temperature−related changes.

Instead of the fan speed jumping instantaneously to its newly determined speed, it ramps

gracefully at the rate determined by these bits. This feature ultimately enhances the acoustics

of the fan.

When Bit 7 of Configuration Register 6 (0x10) is 0

Bit Code

Time for 0% to 100%

000 = 1

001 = 2

010 = 3

011 = 4

100 = 8

101 = 12

110 = 24

111 = 48

37.5 sec

18.8 sec

12.5 sec

7.5 sec

4.7 sec

3.1 sec

1.6 sec

0.8 sec

When Bit 7 of Configuration Register 6 (0x10) is 1

Bit Code

Time for 0% to 100%

000 = 1

001 = 2

010 = 3

011 = 4

100 = 8

101 = 12

110 = 24

111 = 48

52.2 sec

26.1 sec

17.4 sec

10.4 sec

6.5 sec

4.4 sec

2.2 sec

1.1 sec

[3]

EN1

R/W

When this bit is 1, smoothing is enabled on Remote 1 temperature channel.

[4]

SYNC

R/W

SYNC = 1 synchronizes fan speed measurements on TACH2, TACH3, and TACH4 to PWM3.

This allows up to three fans to be driven from PWM3 output and their speeds to be measured.

SYNC = 0 synchronizes only TACH3 and TACH4 to PWM3 output.

[5]

MIN1

R/W

When the ADT7490 is in automatic fan control mode, this bit defines whether PWM1 is off

(0% duty cycle) or at PWM1 minimum duty cycle when the controlling temperature is below

its TMIN − hysteresis value.

0 = 0% duty cycle below TMIN – hysteresis.

1 = PWM1 minimum duty cycle below TMIN – hysteresis.

[6]

MIN2

R/W

When the ADT7490 is in automatic fan speed control mode, this bit defines whether PWM2 is

off (0% duty cycle) or at PWM2 minimum duty cycle when the controlling temperature is

below its TMIN − hysteresis value.

0 = 0% duty cycle below TMIN – hysteresis.

1 = PWM2 minimum duty cycle below TMIN – hysteresis.

[7]

MIN3

R/W

When the ADT7490 is in automatic fan speed control mode, this bit defines whether PWM3 is

off (0% duty cycle) or at PWM3 minimum duty cycle when the controlling temperature is

below its TMIN – hysteresis value.

0 = 0% duty cycle below TMIN – hysteresis.

1 = PWM3 minimum duty cycle below TMIN – hysteresis.

1. This register becomes read-only when the Configuration Register 1 (0x40) LOCK bit is set to 1. Any further attempts to write to this register

have no effect.

2. Setting the relevant bit of Configuration Register 6 (0x10, Bits [2:0]) further decreases these ramp rates by a factor of 4.

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