ADT7468 datasheet(72/80 Pages) AD

72 / 80 page

ADT7468

Rev. 0 | Page 72 of 80

Table 36. Register 0x63 – Enhanced Acoustics Register 2 (Power-On Default = 0x00)

Bit

Name

R/W1

Description

<2:0>

ACOU3

Read/write

These bits select the ramp rate applied to the PWM3 output. Instead of PWM3 jumping instantaneously to

its newly calculated speed, PWM3 ramps gracefully at the rate determined by these bits. This effect

enhances the acoustics of the fan being driven by the PWM3 output.

Time Slot Increase

Time for 33% to 100%

000 = 1

35 s

001 = 2

17.6 s

010 = 3

11.8 s

011 = 5

7 s

100 = 8

4.4 s

101 = 12

3 s

110 = 24

1.6 s

111 = 48

0.8 s

< 3 >

EN3

Read/write

When this bit is 1, acoustic enhancement is enabled on PWM3 output.

<6:4>

ACOU2

Read/write

These bits select the ramp rate applied to the PWM2 output. Instead of PWM2 jumping instantaneously to

its newly calculated speed, PWM2 ramps gracefully at the rate determined by these bits. This effect

enhances the acoustics of the fans being driven by the PWM2 output.

Time Slot Increase

Time for 33% to 100%

000 = 1

35 s

001 = 2

17.6 s

010 = 3

11.8 s

011 = 5

7 s

100 = 8

4.4 s

101 = 12

3 s

110 = 24

1.6 s

<7>

EN2

Read/write

When this bit is 1, acoustic enhancement is enabled on PWM2 output.

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

Table 37. PWM Minimum Duty Cycle Registers

R/W1

Description

Power-On Default

0x64

Read/write

PWM1 minimum duty cycle.

0x80 (50% duty cycle)

0x65

Read/write

PWM2 minimum duty cycle.

0x80 (50% duty cycle)

0x66

Read/write

PWM3 minimum duty cycle.

0x80 (50% duty cycle)

Bit

Name

R/W1

Description

<7:0>

PWM duty cycle

Read/write

These bits define the PWMMIN duty cycle for PWMx.

0x00 = 0% duty cycle (fan off ).

0x40 = 25% duty cycle.

0x80 = 50% duty cycle.

0xFF = 100% duty cycle (fan full speed).

1These registers become read-only when the ADT7468 is in automatic fan control mode.

Table 38. TMIN Registers1

R/W2

Description

Power-On Default

0x67

Read/write

Remote 1 temperature TMIN.

0x5A (90°C)

0x68

Read/write

Local temperatue TMIN.

0x5A (90°C)

0x69

Read/write

Remote 2 temperature TMIN.

0x5A (90°C)

1 These are the TMIN registers for each temperature channel. When the temperature measured exceeds TMIN, the appropriate fan runs at minimum speed and increases

with temperature according to TRANGE.

2 These registers become read-only when the Configuration Register 1 lock bit is set. Any further attempts to write to these registers have no effect.

ADT7468 Datasheet(PDF) 72 Page - Analog Devices

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