adt7476a Analog Devices, Inc., adt7476a Datasheet - Page 49

• Manufacturer Part Number: adt7476a
• Description: Dbcool Remote Thermal Controller And Voltage Monitor
• Manufacturer: Analog Devices, Inc.

Enhance Acoustics Register 1 (0x62)
Bit 7 (MIN3) = 0, PWM3 is off (0% PWM duty cycle) when
temperature is below T
Bit 7 (MIN3) = 1, PWM3 runs at PWM3 minimum duty cycle
below T
Bit 6 (MIN2) = 0, PWM2 is off (0% PWM duty cycle) when
temperature is below T
Bit 6 (MIN2) = 1, PWM2 runs at PWM2 minimum duty cycle
below T
Bit 5 (MIN1) = 0, PWM1 is off (0% PWM duty cycle) when
temperature is below T
Bit 5 (MIN1) = 1, PWM1 runs at PWM1 minimum duty cycle
below T
Configuration Register 6 (0x10)
[0] SLOW = 1, slows the ramp rate for PWM changes associated
with the Remote 1 temperature channel by a factor of 4.
[1] SLOW = 1, slows the ramp rate for PWM changes associated
with the local temperature channel by a factor of 4.
[2] SLOW = 1, slows the ramp rate for PWM changes associated
with the Remote 2 temperature channel by a factor of 4.
[7] ExtraSlow = 1, slows the ramp rate for all fans by a factor
of 39.2%.
The following sections list the ramp-up times when the
SLOW bit is set for each temperature monitoring channel.
Enhance Acoustics Register 1 (0x62)
[2:0] ACOU selects the ramp rate for PWM outputs associated
with the Remote Temperature 1 input.
Enhance Acoustics Register 2 (0x63)
[2:0] ACOU3 selects the ramp rate for PWM outputs associated
with the local temperature channel.
000 = 37.5 sec
001 = 18.8 sec
010 = 12.5 sec
011 = 7.5 sec
100 = 4.7 sec
101 = 3.1 sec
110 = 1.6 sec
111 = 0.8 sec
000 = 37.5 sec
001 = 18.8 sec
010 = 12.5 sec
011 = 7.5 sec
MIN
MIN
MIN
− T
− T
− T
HYST
HYST
HYST
.
.
.
MIN
MIN
MIN
− T
− T
− T
HYST
HYST
HYST
.
.
.
Rev. 0 | Page 49 of 72
[6:4] ACOU2 selects the ramp rate for PWM outputs associated
with the Remote Temperature 2 input.
When Bit 7 of Configuration Register 6 (0x10) = 1, the above
ramp rates change to the values below.
Setting the appropriate slow bit [2:0] of Configuration
Register 6 (0x10) slows the ramp rate further by a factor of 4.
FAN PRESENCE DETECT
This feature is used to determine if a 4-wire fan is directly
connected to a PWM output. This feature does not work for
3-wire fans. To detect whether a 4-wire fan is connected directly
to a PWM output, the following must be performed in this order:
1.
2.
3.
4.
5.
As the detection time only takes 5 ms, programming the
PWM outputs to 100% and then back to its normal speed is
not noticeable in most cases.
100 = 4.7 sec
101 = 3.1 sec
110 = 1.6 sec
111 = 0.8 sec
000 = 37.5 sec
001 = 18.8 sec
010 = 12.5 sec
011 = 7.5 sec
100 = 4.7 sec
101 = 3.1 sec
110 = 1.6 sec
111 = 0.8 sec
000 = 52.2 sec
001 = 26.1 sec
010 = 17.4 sec
011 = 10.4 sec
100 = 6.5 sec
101 = 4.4 sec
110 = 2.2 sec
111 = 1.1 sec
Drive the appropriate PWM outputs to 100% duty cycle.
Set Bit 0 of Configuration Register 2 (0x73).
Wait 5 ms.
Program fans to run at a different speed if necessary.
Read the state of Bits [3:1] of Configuration Register 2
(0x73). The state of these bits reflects whether a 4-wire fan
is directly connected to the PWM output.
ADT7476A