RPM-Based Fan Controller with HW Thermal Shutdown
Datasheet
Table 6.49 Look Up Table Registers (continued)
RPM /
PWM
ADDR
R/W
REGISTER
B7
B6
B5
B4
B3
B2
B1
B0
DEFAULT
LUT Temp 4
Setting 8
7Fh
(127°C)
78h
R/W
X
X
-
64
32
16
8
4
2
1
LUT Temp
Hysteresis
79h
R/W
-
-
-
16
8
4
2
1
0Ah
The Look Up Table Registers hold the 40 entries of the Look Up Table that controls the drive of the
PWM. As the temperature channels are updated, the measured value for each channel is compared
against the respective entries in the Look Up Table and the associated drive setting is loaded into an
internal shadow register and stored.
The bit weighting for temperature inputs represents °C and is compared against the measured data.
Note that the LUT entry does not include a sign bit. The Look Up Table does not support negative
temperature values and the MSBit should not be set for a temperature input.
Each temperature channel threshold shares the same hysteresis value. When the measured
temperature for any of the channels meets or exceeds the programmed threshold, the drive setting
associated with that threshold is used. The temperature must drop below the threshold minus the
hysteresis value before the drive setting will be set to the previous value.
If the RPM based Fan Speed Control Algorithm is used, the TACH Target is updated after every
conversion. It is always set to the minimum TACH Target that is stored by the Look Up Table. The
PWM duty cycle is updated based on the RPM based Fan Speed Control Algorithm configuration
settings.
If the RPM based Fan Speed Control Algorithm is not used, then the PWM duty cycle is updated after
every conversion. It is set to the maximum duty cycle that is stored by the Look Up Table.
6.34
GPIO Direction Register (EMC2103-2 Only)
Table 6.50 GPIO Direction Register
ADDR
R/W
REGISTER
B7
B6
B5
B4
B3
B2
B1
B0
DEFAULT
GPIO
Direction 1
-
-
GPIO
GPIO
00h
E1h
R/W
2_DIR 1_DIR
The GPIO Direction Register controls the direction of GPIOs 1 and 2.
Bit 1 - GPIO2_DIR - Determines the direction of GPIO2.
‘0’ (default) - GPIO2 is configured as an input.
‘1’ - GPIO1 is configured as an output.
Bit 0 - GPIO2_DIR - Determines the direction of GPIO1.
‘0’ (default) - GPIO1 is configured as an input.
‘1’ - GPIO1 is configured as an output.
SMSC EMC2103
Revision 0.85 (01-29-08)
DATA6S5HEET
SMSC [ SMSC CORPORATION ]
