SH3100 Datasheet, PDF (40/80 Pages) Semtech Corporation – Supervisory IC with I2C Interface and PWM

SH3100
POWER MANAGEMENT
Register Descriptions (continued)
Address(hex): 38
Register Name MinStartTemp
Bit 7
Bit 6
Bit 5
Bit No.
[7:0]
Description
MinStartTemp
Address(hex): 39
Register Name DutyCycleStepSize
Bit 7
Bit 6
Bit 5
Bit No.
[7:0]
Description
DutyCycleStepSize
Address(hex): 3A
Register Name ManualPWMDutyCycle
Bit 7
Bit 6
Bit 5
Bit No.
[1:0]
Description
ManualPWMDutyCycle[9:8]
Description
Bit 4
(R/W) Defines the temperature Default Value: 0111 1011
at which auto-fan mode starts ^{Reset Event: P, W}
to drive the fan
Bit 3
Bit 2
Bit 1
Bit 0
MinStartTemp
Bit Value Value Description
This is the ADCCode corresponding to the lowest temperature at
which the automatic fan control mode activates the PWM pin,
and switches on the fan
Code = 163 minus temperature (°C).
In other modes (DeviceCode in the ADCConfig register not equal
to 111), this register has no effect
Default start temperature is 40°C, and the default minimum
duty cycle is 25%
Description
Bit 4
(R/W) The PWM duty cycle
increment for every degree of
rise in the temperature when in
auto-fan-control mode
Default Value: 0001 0001
Reset Event: P, W
Bit 3
Bit 2
Bit 1
Bit 0
DutyCycleStepSize
Bit Value Value Description
In Auto-fan-control mode (DeviceMode bits in the ADCConfig
register = 111), this is how much the PWM duty cycle
increments for every degree of temperature rise. This
effectively defines the temperature at which the PWM duty cycle
would be 100%, i.e., The fan is on at full speed
DutyCycleStepSize = 768/(MaxTemp – MinTemp)
Default value of 17 gives a maximum temperature of 85°C
Description
Bit 4
Bit Value
(R/W) Sets the PWM duty cycle Default Value: 0000 0000
when in ‘normal’ mode.
Reset Event: P, W
Bit 3
Bit 2
Bit 1
Bit 0
PWMDutyCycle[9:8]
Value Description
The most significant 2 bits of the ManualPWMDutyCycle.
When in normal mode, i.e. DeviceMode bits in the ADCConfig
register set to 000, this defines the duty cycle on the PWM pin.
Duty cycle = ManualPWMDutyCycle/1024
© 2006 Semtech Corp.
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