ADT7476 Analog Devices, Inc., ADT7476 Datasheet - Page 66

• Manufacturer Part Number: ADT7476
• Description: Dbcool Remote Thermal Controller And Voltage Monitor
• Manufacturer: Analog Devices, Inc.

ADT7476
Table 43. THERM Limit Registers
Register Address
0x6A
0x6B
0x6C
1
2
Table 44. Temperature/T
Register Address
0x6D
0x6E
1
2
Table 45. XNOR Tree Test Enable
Register Address
0x6F
1
Table 46. Remote 1 Temperature Offset
Register Address
0x70
1
If any temperature measured exceeds its THERM limit, all PWM outputs drive their fans at 100% duty cycle. This is a fail-safe mechanism incorporated to cool the
system in the event of a critical overtemperature. It also ensures some level of cooling in the event that software or hardware locks up. If set to 0x80, this feature is
disabled. The PWM output remains at 100% until the temperature drops below THERM limit – hysteresis. If the THERM pin is programmed as an output, exceeding
these limits by 0.25°C can cause the THERM pin to assert low as an output.
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.
Each 4-bit value controls the amount of temperature hysteresis applied to a particular temperature channel. Once the temperature for that channel falls below its
T
channel. The hysteresis value chosen also applies to that temperature channel if its THERM limit is exceeded. The PWM output being controlled goes to 100% if the
THERM limit is exceeded and remains at 100% until the temperature drops below THERM – hysteresis. For acoustic reasons, it is recommended that the hysteresis
value not be programmed at less than 4°C. Setting the hysteresis value lower than 4°C causes the fan to switch on and off regularly when the temperature is close
to T
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.
This register becomes read-only when the Configuration Register 1 LOCK bit is set to 1. Any subsequent attempts to write to this register fail.
This register becomes read-only when the Configuration Register 1 LOCK bit is set to 1. Any subsequent attempts to write to this register fail.
MIN
MIN
value, the fan remains running at PWM
.
Bit Name
HYSL [3:0]
HYSR1 [7:4]
HYSR2 [7:4]
Bit Name
XEN [0]
Reserved [7:1]
Bit
[7:0]
MIN
Hysteresis Registers
R/W
R/W
R/W
R/W
1
MIN
2
duty cycle until the temperature = T
R/W
R/W
R/W
R/W
R/W
R/W
R/W
2
1
1
Description
Remote 1 and Local Temperature hysteresis.
Local temperature hysteresis. 0°C to 15°C of hysteresis can be
applied to the local temperature AFC control loops.
Remote 1 temperature hysteresis. 0°C to 15°C of hysteresis can
be applied to the Remote 1 Temperature AFC control loops.
Remote 2 temperature hysteresis.
RemotetTemperature hysteresis. 0°C to 15°C of hysteresis can
be applied to the local temperature AFC control loops.
Description
XNOR tree test enable.
If the XEN bit is set to 1, the device enters the XNOR tree test
mode. Clearing the bit removes the device from the XNOR tree
test mode.
Unused. Do not write to these bits.
Description
Remote 1 temperature offset.
Allows a temperature offset to be applied automatically to the
Remote 1 temperature channel measurement. Bit 1 of
Configuration Register 5 (0x7C) determines the range and
resolution of this register.
1
Description
Remote 1 THERM temperature limit
Local THERM temperature limit
Remote 2 THERM temperature limit
Rev. B | Page 66 of 72
MIN
– hysteresis. Up to 15°C of hysteresis can be assigned to any temperature
Power-On Default
0x64 (100°C)
0x64 (100°C)
0x64 (100°C)
Power-On Default
0x00
Power-On Default
0x00
Power-On Default
0x44
0x40