ADT7475 Analog Devices, Inc., ADT7475 Datasheet - Page 55

• Manufacturer Part Number: ADT7475
• Description: Dbcool Remote Thermal Monitor And Fan Controller
• Manufacturer: Analog Devices, Inc.

ADT7475
Table 29. Register 0x55—TACH1 Minimum High Byte (Power-On Default = 0xFF)
Bits
[4:0]
[7:5]
Table 30. PWM Configuration Registers
Register Address
0x5C
0x5D
0x5E
1
Table 31. Register 0x5C, Register 0x5D, and Register 0x5E—PWM Configuration Registers (Power-On Default = 0x62)
Bit
[2:0]
[4]
[7:5]
These registers become read-only when the Configuration Register 1 lock bit is set to 1. Any subsequent attempts to write to these registers fail.
Name
Reserved
SCADC
Name
SPIN
INV
BHVR
Read-only
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Description
These bits are reserved when Bit 6 of Configuration Register 2 (0x73) is set (single-channel ADC mode).
Otherwise, these bits represent Bits [4:0] of the TACH1 minimum high byte register.
When Bit 6 of Configuration Register 2 (0x73) is set (single-channel ADC mode), these bits are used to
select the only channel from which the ADC makes measurements. Otherwise, these bits represent Bits
[7:5] of the TACH1 minimum high byte register.
P
Description
These bits control the start-up timeout for PWMx. The PWM output stays high until two valid TACH
rising edges are seen from the fan. If there is not a valid TACH signal during the fan TACH
measurement directly after the fan start-up timeout period, the TACH measurement reads 0xFFFF and
Interrupt Status Register 2 reflects the fan fault. If the TACH minimum high and low bytes contain
0xFFFF or 0x0000, the Interrupt Status Register 2 bit is not set, even if the fan has not started.
000 = No start-up timeout
001 = 100 ms
010 = 250 ms (default)
011 = 400 ms
100 = 667 ms
101 = 1 sec
110 = 2 sec
111 = 4 sec
This bit inverts the PWM output. The default is 0, which corresponds to a logic high output for 100%
duty cycle. Setting this bit to 1 inverts the PWM output so that 100% duty cycle corresponds to a logic
low output.
These bits assign each fan to a particular temperature sensor for localized cooling.
000 = Remote 1 temperature controls PWMx (automatic fan control mode).
001 = Local temperature controls PWMx (automatic fan control mode).
010 = Remote 2 temperature controls PWMx (automatic fan control mode).
011 = PWMx runs full speed.
100 = PWMx disabled (default).
101 = Fastest speed calculated by local and Remote 2 temperature controls PWMx.
110 = Fastest speed calculated by all three temperature channel controls PWMx.
111 = Manual Mode. PWM duty cycle registers (0x30 to 0x32) become writable.
1
Description
PWM1 configuration.
PWM2 configuration.
PWM3 configuration.
Rev. B | Page 55 of 68
Power-On Default
0x62
0x62
0x62