RPM-Based PWM Fan Controller
Datasheet
Chapter 5 Register Set
5.1
Register Map
The following registers are accessible through the SMBus Interface. All register bits marked as ‘-’ will
always read ‘0’. A write to these bits will have no effect.
Table 5.1 EMC2301 Register Set
REGISTER
NAME
DEFAULT
VALUE
ADDR
R/W
FUNCTION
Configuration and control
LOCK
PAGE
20h
24h
25h
26h
27h
29h
2Ah
2Bh
2Dh
R/W
R-C
R-C
R-C
R-C
R/W
R/W
R/W
R/W
Configuration
Fan Status
Fan Stall Status
Fan Spin Status
Drive Fail Status
Fan Interrupt
Enable Register
PWM Polarity
Config
PWM Output
Config
PWM Base
Frequency
Configures the clocking and watchdog
functionality
Stores the status bits for the RPM-
based Fan Speed Control Algorithm
Stores status bits associated with a
stalled fan
Stores status bits associated with a
spin-up failure
Stores status bits associated with drive
failure
Controls the masking of interrupts on all
fan related channels
Configures Polarity of the PWM driver
Configures Output type of the PWM
driver
Selects the base frequency for the
PWM output
Fan Control Registers
Always displays the most recent fan
driver input setting for the Fan. If the
RPM-based Fan Speed Control
Algorithm is disabled, allows direct user
control of the fan driver.
Stores the divide ratio to set the
frequency for the Fan
Sets configuration values for the RPM-
based Fan Speed Control Algorithm for
the Fan driver
Sets additional configuration values for
the Fan driver
Holds the gain terms used by the RPM-
based Fan Speed Control Algorithm for
the Fan driver
40h
00h
00h
00h
00h
00h
00h
00h
00h
SWL
No
No
No
No
No
No
No
No
30h
R/W
Fan Setting
00h
No
31h
R/W
PWM Divide
Fan Configuration
1
Fan Configuration
2
Gain
01h
No
32h
R/W
2Bh
No
33h
R/W
28h
SWL
35h
R/W
2Ah
SWL
SMSC EMC2301
23
Revision 1.1 (10-12-09)
DATASHEET
SMSC [ SMSC CORPORATION ]
