EMC2103-2-AP-TR Standard Microsystems (SMSC), EMC2103-2-AP-TR Datasheet - Page 55

• Manufacturer Part Number: EMC2103-2-AP-TR
• Description: CLOSED LOOP RPM FAN CONTROLLER
• Manufacturer: Standard Microsystems (SMSC)

RPM-Based Fan Controller with HW Thermal Shutdown
Datasheet
SMSC EMC2103
6.20
6.21
6.22
ADDR
ADDR
ADDR
41h
42h
40h
R/W
R/W
R/W
R/W
R/W
R/W
The Fan Setting Register always displays the current setting of the Fan Driver. Reading from the
register will report the current fan speed setting of the fan driver regardless of the operating mode.
Therefore it is possible that reading from this register will not report data that was previously written
into this register.
While the RPM based Fan Speed Control Algorithm or the Look Up Table are active (or both), then
the register is read only. Writing to the register will have no affect and the data will not be stored.
If both the RPM based Fan Control Algorithm and the Look Up Table are disabled, then the register
will be set with the previous value that was used. The register is read / write and writing to this register
will affect the fan speed.
The contents of the register represent the weighting of each bit in determining the final duty cycle. The
output drive for a PWM output is given by
The PWM Divide Register determines the final frequency of the PWM driver. The driver base frequency
is divided by the value of the PWM Divide Register to determine the final frequency. The duty cycle
settings are not affected by these settings, only the final frequency of the PWM driver. A value of 00h
will be decoded as 01h.
The final PWM frequency is derived as the base frequency divided by the value of this register as
shown in
Fan Setting Registers
PWM Divide Register
Fan Configuration 1 Register
Configuration 1
REGISTER
PWM Divide
REGISTER
Equation
Fan Setting
REGISTER
Fan
[2].
f
Table 6.30 Fan Configuration 1 Register
PWM
Table 6.28 Fan Driver Setting Register
Drive
ALGO
128
EN_
B7
B7
Table 6.29 PWM Divide Register
128
B7
=
PWM base freqeuncy
-------------------------------------------------------------- -
=
PWM Divide Setting
B6
⎛
⎝
64
RANGE[1:0]
VALUE
-------------------- -
DATASHEET
B6
B6
64
255
B5
32
⎞
⎠
55
Equation
B5
B5
32
×
100%
B4
16
EDGES[1:0]
B4
B4
16
[1].
B3
B3
8
B3
8
4
B2
B2
B2
4
UPDATE[2:0]
B1
B1
B1
2
2
[1]
[2]
Revision 0.88 (06-30-08)
1
B0
B0
B0
1
DEFAULT
DEFAULT
DEFAULT
00h
2Bh
01h