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TargetDCYatT1=DCY-LOW-TEMP+(T1 LOW-TEMP) SLOPE;- ´
HIGH-TEMP=(LOW-TEMP)+
(100 DCY-LOW-TEMP)-
SLOPE
(3)
NormalRange
DCY-LOW-TEMP
(DCYatLowTemperature,
Defaultis33%)
100%
LOW-TEMP(LowTemperature)
HIGH-
TEMP
(High Temperature)
RPM=0
ActualTemperature
Critical-Temp
PSV-Temp
(PassiveCoolingTemperature)
Low-Temp-Limit
High-Temp-Limit
Out-of-Range Out-of-Range
THERM-Limit
Temperature-to-DCYAdjustmentRange
DCYincreaseswhenthetemperaturerises.
DCYdecreaseswhenthetemperaturereduces.
0%
DutyCycle
AMC6821
SBAS386C – MAY 2006 – REVISED JULY 2007
The bits [R-TEMP4:R-TEMP0] of the Remote TEMP-FAN Control Register and the bits [L-TEMP4:L-TEMP0] of
the Local TEMP-FAN Control Register are the low temperature bits that define the low temperature of the control
loops. Bits [SPL2:SPL0] of these registers are the slope bits that define the increment of the duty cycle when the
temprature increases 1 ° C. The bits [RATE2:RATE0] of the DCY-RAMP Register (bits [4:1], 0x23) specify the
updating rate of the duty cycle in the temp-fan control mode, and the bits [STEP1:STEP0] define how much the
duty cycle is adjusted by each updating. The target duty cycle for temperature T1 and the HIGH-TEMP (high
temperature) can be calculated by Equation 3 :
Figure 28. Active Control Temperature — PWM Duty Cycle
When the active control temperature is equal to or below the corresponding low temperature, the duty cycle is
equal to the value of the DCY-LOW-TEMP Register and the fan runs at a predefined minimum speed. When the
control temperature is equal to or higher than the corresponding high temperature, the PWM duty cycle is set to
100% and the fan runs at full speed. When the active control temperature is equal to or below the corresponding
value of the PSV-Temp Register (the predefined passive cooling temperature), the fan stops and the PWM duty
cycle is set to 0.
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