emc2101 Standard Microsystems Corp., emc2101 Datasheet - Page 40

• Manufacturer Part Number: emc2101
• Description: Emc2101 Fan Control With 1?c Accurate Temperature Monitoring
• Manufacturer: Standard Microsystems Corp.

Revision 2.53 (02-19-08)
ADDR.
6.16
4Ah
R/W
R/W
The Fan Configuration Register enables the Fan Control Look-Up Table and polarity of the PWM signal
driving the output.
Bit 6 - FORCE - enables the External Temperature Force Register. This bit is not used if the Fan
Control Look-Up Table is not used.
Bit 5 - PROG - enables the Fan Control Look-Up Table for update and sets fan driver output based
on Fan Control Look-Up Table values.
Bit 4 - POLARITY- sets the polarity of the Fan output driver. For the EMC2101-R, the value of this bit
is determined by the value of the pull-up resistor on the ALERT / TACH pin (see
PWM default value is set at 100% duty cycle, the default value is set to ‘1’ and when the PWM default
value is set to 0% duty cycle, the default value is set to ‘0’. This occurs within 10ms after power-up.
Bit 3 - CLK_SEL - Determines the base clock that is used to determine the final PWM frequency.
Bit 2 - CLK_OVR - Overrides the CLK_SEL bit and uses the Frequency Divide Register to determine
the base PWM frequency. It is recommended that this bit be set for maximum PWM resolution.
Bit 1-0 - TACH_M[1:0] - Determines the basic operation of the tachometer input as shown in
Table
Fan Configuration Register
REGISTER
Fan Config
‘0’ (default) - the External Diode Force Register is not used. The measured External Diode
temperature is used to determine the position in the Fan Control Look-Up Table.
‘1’ - the External Temperature Force Register is used. When determining the position in the Fan
Control Look-Up Table, the contents of the External Temperature Force Register will be used
instead of the measured External Diode temperature. All limits will be checked against the
measured External Diode temperature as normal.
‘0’ - the Fan Setting Register and Fan Control Look-Up Table Registers are read-only and the Fan
Control Look-Up Table Registers will be used.
‘1’ (default) - the Fan Setting Register and Fan Control Look-Up Table Registers can be written.
The value written into the Fan Setting Register will be instantly applied to the fan driver and the
Fan Control Look-Up Table will not be used.
‘0’ (default - EMC2101) - The polarity of the Fan output driver is non-inverted. A ‘00h’ setting will
correspond to a 0% duty cycle or minimum DAC output voltage.
‘1’ - The polarity of the Fan output driver is inverted. A ‘00h’ setting will correspond to a 100% duty
cycle or maximum DAC output voltage.
‘0’ (default) - The base clock that is used to determine the PWM frequency is 360kHz.
‘1’ - The base clock that is used to determine the PWM frequency is 1.4kHz.
‘0’ (default) - The base clock frequency for the PWM is determined by the CLK_SEL bit.
‘1’ (recommended) - The base clock that is used to determine the PWM frequency is set by the
Frequency Divide Register
6.19.
B7
-
Table 6.18 Fan Configuration Register
FORCE
B6
DATASHEET
PROG
B5
40
POLARITY
SMBus Fan Control with 1°C Accurate Temperature Monitoring
B4
CLK_
SEL
B3
CLK_
OVR
B2
TACH_M[1:0]
B1
Table
B0
SMSC EMC2101
5.1). When the
DEFAULT
Datasheet
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