Datasheet
AMC6821-Q1
SBAS475 – JUNE 2009 ......................................................................................................................................................................................................
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Table 14. 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)
0 0 PSV8 PSV7 PSV6 PSV5 PSV4 PSV3
0x1C PSV-Temp R/W 0x00
Passive Cooling Temperature threshold. 3 LSBs and two MSBs are '0'. For details, refer to the passive cooling
temperature limit in the Temperature Out-of-Range Detection section. Default = 0 ° C.
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 are written into this register. 8-bit,
0.39%/bit, range 0%-100%. Default = 33%.
In read operation, the returned data are the actual DCY value driving the PWM-Out pin with two exceptions. Refer to the
0x22 DCY (Duty Cycle) R/W 0x55
DCY Register section.
In write operation, the data written are the actual DCY value driving the PWM-Out pin in Software-DCY control mode.
In all other control modes, the data are not used to drive the PWM. Instead, they are stored in a temporary register, and
used to control the PWM immediately after the control mode is changed to software-DCY control.
RAMPE STEP1 STEP0 RATE2 RATE1 RATE0 THRE1 THRE0
0x23 DCY-RAMP R/W 0x52
DCY Adjustment Step in DCY Update Rate in Auto Temp-Fan Adjustment Threshold in
Ramp Enable
Auto Fan Control Control 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
(1)
R/W 0x41
Low-Temp 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-Temp in Auto Remote Temp-Fan control. Slope in Auto Remote Temp-Fan control.
TACH (RPM) MEASUREMENT
TACH- TACH- TACH- TACH- TACH- TACH- TACH- TACH-
DATA7 DATA6 DATA5 DATA4 DATA3 DATA2 DATA1 DATA0
0x08 TACH-DATA-LByte R 0x00
Low byte of TACH measurement.
TACH- TACH- TACH- TACH- TACH- TACH- TACH- TACH-
DATA15 DATA14 DATA13 DATA12 DATA11 DATA10 DATA9 DATA8
0x09 TACH-DATA-HByte R 0x00
High byte of TACH measurement.
TACH-Low- TACH-Low- TACH-Low- TACH-Low- TACH-Low- TACH-Low- TACH-Low- TACH-Low-
Limit7 Limit6 Limit5 Limit4 Limit3 Limit2 Limit1 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- TACH-Low- TACH-Low- TACH-Low- TACH-Low- TACH-Low- TACH-Low- TACH-Low-
Limit15 Limit14 Limit13 Limit12 Limit11 Limit10 Limit9 Limit8
0x11 TACH-Low-Limit-HByte R/W 0xFF
High byte of TACH Limit corresponding to minimum allowed RPM.
TACH-High- TACH-High- TACH-High- TACH-High- TACH-High- TACH-High- TACH-High- TACH-High-
Limit7 Limit6 Limit5 Limit4 Limit3 Limit2 Limit1 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- TACH-High- TACH-High- TACH-High- TACH-High- TACH-High- TACH-High- TACH-High-
Limit15 Limit14 Limit13 Limit12 Limit11 Limit10 Limit9 Limit8
0x13 TACH-High-Limit-HByte R/W 0x00
High byte of TACH limit corresponding to maximum allowed RPM.
TACH- TACH- TACH- TACH- TACH- TACH- TACH- TACH-
SETTING7 SETTING6 SETTING5 SETTING4 SETTING3 SETTING2 SETTING1 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- TACH- TACH- TACH- TACH- TACH- TACH- TACH-
SETTING15 SETTING14 SETTING13 SETTING12 SETTING11 SETTING10 SETTING9 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'.
(1) Used to calculate the target PWM duty cycle for local temperature in maximum fast-speed calculated control.
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