EVAL-ADT7475EB ON Semiconductor, EVAL-ADT7475EB Datasheet - Page 52

• Manufacturer Part Number: EVAL-ADT7475EB
• Description: BOARD EVALUATION FOR ADT7475
• Manufacturer: ON Semiconductor
• Series: dBCool®r
• Type: Temperature Sensorr

Specifications of EVAL-ADT7475EB

• Contents: Evaluation Board
• For Use With/related Products: ADT7475
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

1. These are the T
2. These registers become read−only when the Configuration Register 1 lock bit is set. Any subsequent attempts to write to these registers fail.
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
2. 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.
1. Each 4−bit value controls the amount of temperature hysteresis applied to a particular temperature channel. Once the temperature for that
2. 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.
Table 33. Register 0x64, Register 0x65, Register 0x66 — PWM Minimum Duty Cycle Registers
(Power−On Default = 0x80; 50% Duty Cycle)
Table 34. T
Table 35. THERM Temperature Limit Registers
Table 36. Temperature/T
Bit No.
[7:0]
Register Address
Register Address
Register Address
minimum speed and increases with temperature according to T
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 a THERM
Limit − Hysteresis. If the THERM pin is programmed as an output, then exceeding these limits by 0.25°C can cause the THERM pin to assert
low as an output.
channel falls below its T
hysteresis can be assigned to any temperature 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 to 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
0x6A
0x6B
0x6C
0x6D
0x6E
0x67
0x68
0x69
Mnemonic
PWM Duty
MIN
Cycle
Registers
MIN
registers for each temperature channel. When the temperature measured exceeds T
MIN
(Note 2)
(Note 2)
MIN
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
(Note 1 and 2)
value, the fan remains running at PWM
Hysteresis Registers
These bits define the PWM
Remote 1 temperature T
Local temperature T
Remote 2 temperature T
Remote 1 THERM temperature limit.
Local THERM temperature limit.
Remote 2 THERM temperature limit.
Bit Name
HYSR1
HYSR2
HYSL
0x00 = 0% duty cycle (fan off).
0x40 = 25% duty cycle.
0x80 = 50% duty cycle.
0xFF = 100% duty cycle (fan full speed).
[3:0]
[7:4]
[7:4]
Remote 1 and local temperature hysteresis.
Local temperature hysteresis. 0°C to 15°C of hysteresis
can be applied to the local temperature and AFC loops.
Remote 1 temperature hysteresis. 0°C to 15°C of
hysteresis can be applied to the Remote 1 temperature
and AFC loops.
Remote 2 temperature hysteresis.
Local temperature hysteresis. 0°C to 15°C of hysteresis
can be applied to the local temperature and AFC loops.
(Note 1)
http://onsemi.com
(Note 1)
MIN
RANGE
MIN
MIN
Description
Description
52
MIN
MIN
.
duty cycle for PWMx.
duty cycle until the temperature = T
Description
Description
MIN
MIN
, the appropriate fan runs at
− hysteresis. Up to 15°C of
Power−On Default
Power−On Default
0x64 (100°C)
0x64 (100°C)
0x64 (100°C)
0x5A (90°C)
0x5A (90°C)
0x5A (90°C)
Power−On Default
0x44
0x40
MIN
.