EMC2103 Standard Microsystems Corporation, EMC2103 Datasheet - Page 54

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

Revision 0.85 (01-29-08)
6.20
6.21
ADDR
ADDR
ADDR
3Ah **
39h **
41h
40h
3Ch
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
The EMC2103 contains high limits for all temperature channels. If any measurement meets or exceeds
the high limit then the appropriate status bit is set and the ALERT pin is asserted (if enabled).
Additionally, the EMC2103 contains low limits for all temperature channels. If the temperature channel
drops below the low limit, then the appropriate status bit is set and the ALERT pin is asserted (if
enabled).
All Limit Registers are Software Locked.
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
Fan Setting Registers
PWM Divide Register
External Diode
External Diode
2 Low Limit **
3 Low Limit **
Internal Diode
PWM Divide
REGISTER
REGISTER
Low Limit
Fan Setting
REGISTER
Table 6.26 Limit Registers (continued)
Table 6.27 Fan Driver Setting Register
Drive
128
B7
Sign
Sign
Sign
B7
Table 6.28 PWM Divide Register
128
B7
=
B6
⎛
⎝
64
B6
VALUE
-------------------- -
64
64
64
DATASHEET
B6
64
255
B5
32
⎞
⎠
54
B5
32
32
32
Equation
B5
32
×
100%
B4
16
B4
B4
16
16
16
16
[1].
RPM-Based Fan Controller with HW Thermal Shutdown
B3
8
B3
B3
8
8
8
8
4
B2
B2
B2
4
4
4
4
B1
B1
B1
2
2
2
2
2
[1]
1
B0
B0
B0
1
1
1
1
SMSC EMC2103
DEFAULT
DEFAULT
DEFAULT
(0°C)
(0°C)
(0°C)
Datasheet
00h
00h
00h
00h
01h