ADT7470 Analog Devices, Inc., ADT7470 Datasheet - Page 34

• Manufacturer Part Number: ADT7470
• Description: Temperature Sensor Hub And Fan Controller
• Manufacturer: Analog Devices, Inc.

ADT7470
Table 42. Register 0x74. Configuration Register 2 (Power-On Default = 0x00)
Bit Name
<7> SHDN
<6:4> FREQ
<3> T4_dis
<2> T3_dis
<1> T2_dis
<0> T1_dis
Table 43. Register 0x75. Enhance Acoustics 1 (Power-On Default = 0x00)
Bit Name
<7> EN1
<6:4> ACOU1
<3> EN2
<2:0> ACOU2
Read/Write
Read/Write
Read/Write
Read/Write
Read/Write
Read/Write
Read/Write
Read/Write
Read/Write
Read/Write
Read/Write
Read/Write
Description
Shutdown/low current mode.
These bits control PWM1–PWM4 frequency when the fan drive is configured as a low
frequency drive.
Register 0x74<6:4>
000
001
010
011
100
101
110
111
Writing a 1 disables Tach 4 pulses.
Writing a 1 disables Tach 3 pulses.
Writing a 1 disables Tach 2 pulses.
Writing a 1 disables Tach 1 pulses.
Description
When this bit is 1, acoustic enhancement is enabled on PWM1 output.
These bits select the ramp rate applied to the PWM1 output. Instead of PWM1 jumping
instantaneously to its newly calculated speed, PWM1 ramps gracefully at the rate deter-
mined by these bits. This affects the acoustics of the fans being driven by the PWM1 output.
Time Slot
000 = 1
001 = 2
010 = 3
011 = 5
100 = 8
101 = 12
110 = 24
111 = 48
When this bit is 1, acoustic enhancement is enabled on PWM2 output.
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 deter-
mined by these bits. This affects the acoustics of the fans being driven by the PWM2 output.
Time Slot
000 = 1
001 = 2
010 = 3
011 = 5
100 = 8
101 = 12
110 = 24
111 = 48
Rev. B | Page 34 of 40
Register 0x40<6> = 1
11.0 Hz
14.7 Hz
22.1 Hz
29.4 Hz
35.3 Hz
44.1 Hz
58.8 Hz
88.2 Hz
Increase Time for 33% to PWMMAX
35 s
17.6 s
11.8 s
7 s
4.4 s
3 s
1.6 s
0.8 s
Increase Time for 33% to PWMMAX
35 s
17.6 s
11.8 s
7 s
4.4 s
3 s
1.6 s
0.8 s
Register 0x40<6> = 0
1.4 kHz
22.5 kHz
22.5 kHz
22.5 kHz
22.5 kHz
22.5 kHz
22.5 kHz
22.5 kHz