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P
AMC6821
SBAS386A–MAY 2006–REVISED MAY 2006
REGISTER MAP (continued)
Table 7. Memory Map (continued)
ADDR
NAME
R/W
DEFAULT
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
TEMPERATURE MONITORING (continued)
RT-C10
RT-C9
RT-C8
RT-C7
RT-C6
RT-C5
RT-C4
RT-C3
0x1D
Remote-Critical-Temp
R/W
0x69
The 8 MSBs of Remote Critical temperature shutdown threshold. 3 LSBs are '0'. When the Remote-Temp is equal to or
above this limit, an RCRT interrupt occurs and OVR goes low. Default = +105
°
C.
PWM CONTROLLER
FSPD
0
PWM2
PWM1
PWM0
STIME2
STIME1
STIME0
0x20
FAN-Characteristics
R/W
0x1D
Spin Dis
PWM Frequency Setting
Spin-Up Time Setting
L-DCY7
L-DCY6
L-DCY5
L-DCY4
L-DCY3
L-DCY2
L-DCY1
L-DCY0
0x21
DCY-Low-Temp
R/W
0x55
The duty cycle of PWM when the temperature is equal to or below Low-Temp in Auto Temp-Fan Control mode.
Default = 0x55, 33.2%.
DCY7 (MSB)
DCY6
DCY5
DCY4
DCY3
DCY2
DCY1
DCY0
Actual Duty cycle of PWM output. The duty cycle changes immediately after new data is written into this register. 8-bit,
0.39%/bit, range 0%-100%. Default = 33%.
In read operation, the returned data is the actual DCY value driving the PWM-Out pin.
In write operation, the data written is the actual DCY driving the PWM-Out pin in Software-DCY control mode.
In all other control modes, the data is not used to drive the PWM. Instead, it is stored in a temporary register, and is used
to control the PWM immediately after the control mode is changed to software-DCY control.
0x22
DCY (Duty Cycle)
R/W
0x55
RAMPE
STEP1
STEP0
RATE2
RATE1
RATE0
THRE1
THRE0
0x23
DCY-RAMP
R/W
0x52
Ramp Enable
DCY Adjustment Step in
Auto Fan Control
DCY Update Rate in Auto Temp-Fan
Control
Adjustment Threshold in
Auto Temp-Fan Control
L-TEMP4
L-TEMP3
L-TEMP2
L-TEMP1
L-TEMP0
L-SLP2
L-SLP1
L-SLP0
0x24
Local Temp-Fan Control
R/W
0x41
Low Temperature in Auto Local Temp-Fan control.
Slope in Auto Local Temp-Fan control.
R-TEMP4
R-TEMP3
R-TEMP2
R-TEMP1
R-TEMP0
R-SLP2
R-SLP1
R-SLP0
0x25
Remote Temp-Fan Control
R/W
0x61
Low Temperature in Auto Remote Temp-Fan control.
Slope in Auto Remote Temp-Fan control.
TACH (RPM) MEASUREMENT
TACH-
DATA6
TACH-
DATA5
TACH-
DATA4
TACH-
DATA3
TACH-
DATA2
TACH-
DATA1
TACH-
DATA0
TACH-DATA7
0x08
TACH-DATA-LByte
R
0x00
Low byte of TACH measurement.
TACH-
DATA15
TACH-
DATA14
TACH-
DATA13
TACH-
DATA12
TACH-
DATA11
TACH-
DATA10
TACH-
DATA9
TACH-
DATA8
0x09
TACH-DATA-HByte
R
0x00
High byte of TACH measurement.
TACH-Low-
Limit7
TACH-Low-
Limit6
TACH-Low-
Limit5
TACH-Low-
Limit4
TACH-Low-
Limit3
TACH-Low-
Limit2
TACH-Low-
Limit1
TACH-Low-
Limit0
0x10
TACH-Low-Limit-LByte
R/W
0xFF
Low byte of TACH count limit corresponding to minimum allowed RPM. Since the TACH circuit counts between TACH
pulses, a slow fan results in a larger measured value. When the measured value is larger than TACH-Low-Limit, the fan
runs below the allowed minimum speed limit.
TACH-Low-
Limit15
TACH-Low-
Limit14
TACH-Low-
Limit13
TACH-Low-
Limit12
TACH-Low-
Limit11
TACH-Low-
Limit10
TACH-Low-
Limit9
TACH-Low-
Limit8
0x11
TACH-Low-Limit-HByte
R/W
0xFF
High byte of TACH Limit corresponding to minimum allowed RPM.
TACH-High-
Limit7
TACH-High-
Limit6
TACH-High-
Limit5
TACH-High-
Limit4
TACH-High-
Limit3
TACH-High-
Limit2
TACH-High-
Limit1
TACH-High-
Limit0
0x12
TACH-High-Limit-LByte
R/W
0x00
Low byte of TACH count Limit corresponding to maximum allowed RPM. Since the TACH circuit counts between TACH
pulses, a fast fan results in a small measured value. When the measurement is less than this limit, the fan runs above the
allowed maximum speed limit.
TACH-High-
Limit15
TACH-High-
Limit14
TACH-High-
Limit13
TACH-High-
Limit12
TACH-High-
Limit11
TACH-High-
Limit10
TACH-High-
Limit9
TACH-High-
Limit8
0x13
TACH-High-Limit-HByte
R/W
0x00
High byte of TACH limit corresponding to maximum allowed RPM.
TACH-
SETTING7
TACH-
SETTING6
TACH-
SETTING5
TACH-
SETTING4
TACH-
SETTING3
TACH-
SETTING2
TACH-
SETTING1
TACH-
SETTING0
0x1E
TACH-SETTING-LByte
R/W
0xFF
Low byte of TACH value corresponding to the predetermined target fan speed. TACH-SETTING must be not greater than
the value corresponding to the RPM for 30% duty cycle when the TACH-MODE bit is cleared ('0').
TACH-
SETTING15
TACH-
SETTING14
TACH-
SETTING13
TACH-
SETTING12
TACH-
SETTING11
TACH-
SETTING10
TACH-
SETTING9
TACH-
SETTING8
0x1F
TACH-SETTING-HByte
R/W
0xFF
High byte of TACH value corresponding to the predetermined fan speed. TACH-SETTING must be not greater than the
value corresponding to the RPM for 30% duty cycle when the TACH-MODE bit is cleared ('0').
0x3A
Reserved
R
0x00
Always read '0'.
0x3B
Reserved
R
0x00
Always read '0'.
30
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