emc2101 Standard Microsystems Corp., emc2101 Datasheet - Page 43

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

SMBus Fan Control with 1°C Accurate Temperature Monitoring
Datasheet
APPLICATION NOTE: The output of the DAC driver is dependent upon the current load. With a low current load,
SMSC EMC2101
6.19
6.20
ADDR.
ADDR.
4Dh
4Eh
R/W
R/W
R/W
R/W
These values are independent of the POLARITY bit (see
the Fan Setting Register will always refer to minimum output drive while a setting of 3Fh in the Fan
Setting Register will always refer to maximum output drive.
The PWM Frequency Register determines the final PWM frequency and “effective resolution” of the
PWM driver. It has no affect on the DAC output resolution.
It is recommended that this register be set at 1Fh for maximum resolution. See
operation of the PWM_F register and its interactions with the PWM Resolution and Duty Cycle
This register holds an alternate PWM Frequency divide value that can be used instead of the CLK_SEL
bit function. This register can be written at any time, however unless the CLK_OVR bit is set to a logic
‘1’, it is not used.
When the CLK_OVR bit is set to a logic ‘1’, the PWM Frequency Divide Register is used in conjunction
with the PWM Frequency Register to determine the final PWM frequency that the load will see. When
the CLK_OVR bit is set to a logic ‘0’, the setting of this register is not changed and is not used to
determine the effective PWM frequency.
The PWM frequency when the PWM Frequency Divide Register is used is shown in
PWM Frequency Register
PWM Frequency Divide Register
PWM Frequency
PWM Frequency
the output will be from 0V to an LSB (approximately 52mV at V
a maximum of 64 linear steps.
REGISTER
REGISTER
Divide
Table 6.25 PWM Frequency Divide Register
FAN
Table 6.24 PWM Frequency Register
=
B7
B7
-
⎛
⎝
FAN_SETTING
--------------------------------------------
DATASHEET
B6
B6
-
64
43
B5
B5
-
⎞
⎠
×
PWM_D[7:0]
B4
V
DD
B4
B3
Section
B3
PWM_F[4:0]
B2
6.16). Therefore, a value of 00h in
B2
B1
DD
B1
= 3.3V) below V
Revision 2.53 (02-19-08)
B0
B0
Appendix A
Equation
DEFAULT
DEFAULT
01h
17h
DD
[5].
for full
[4]
with