EMC2103 Standard Microsystems Corporation, EMC2103 Datasheet - Page 56

• Manufacturer Part Number: EMC2103
• Description: Rpm-based Fan Controller with HW Thermal Shutdown
• Manufacturer: Standard Microsystems Corporation

ADDR
43h
Revision 0.85 (01-29-08)
6.23
0
0
1
1
1
R/W
R/W
EDGES[1:0]
2
0
0
0
0
1
1
1
1
term that is applied to the Actual RPM to achieve the Reported RPM. It should only be applied if the
number of edges measured does not match the number of edges expected based on the number of
poles of the fan (which is fixed for any given fan).
Contact SMSC for recommended settings when using fans with more or less than 2 poles.
Bit 2-0 - UPDATE - determines the base time between fan driver updates. The Update Time, along
with the Fan Step Register, is used to control the ramp rate of the drive response to provide a cleaner
transition of the actual fan operation as the desired fan speed changes. The Update Time is set as
shown in
Fan Configuration 2 Register
0
1
0
1
Configuration
REGISTER
Fan
0
2
Table
UPDATE[2:0]
6.32.
MINIMUM TACH
B7
1
0
0
1
1
0
0
1
1
Table 6.31 Minimum Edges for Fan Rotation
-
Table 6.33 Fan Configuration 2 Register
EDGES
3
5
7
9
RRC
EN_
B6
Table 6.32 Update Time
DATASHEET
GLITCH
_EN
B5
1 pole
2 poles (default)
3 poles
4 poles
NUMBER OF FAN POLES
56
0
0
1
0
1
0
1
0
1
DER_OPT [1:0]
B4
RPM-Based Fan Controller with HW Thermal Shutdown
B3
ERR_RNG:0]
B2
MULTIPLIER (BASED ON 2
400ms (default)
UPDATE TIME
B1
EFFECTIVE TACH
1200ms
1600ms
100ms
200ms
300ms
500ms
800ms
POLE FANS)
0.5
1.5
B0
1
2
-
SMSC EMC2103
Datasheet
DEFAULT
38h