EMC2301_11 Datasheet, PDF (25/43 Pages) SMSC Corporation – RPM-Based PWM Fan Controller

RPM-Based PWM Fan Controller
Datasheet
5.2
Configuration Register
ADDR R/W
REGISTER
B7
Table 5.2 Configuration Register
B6
B5
B4
B3
20h
R/W Configuration MASK DIS_TO WD_EN
-
-
B2
B1
B0
DEFAULT
-
DR_EXT_
CLK
USE_
EXT_
CLK
40h
5.3
The Configuration Register controls the basic functionality of the EMC2301. The bits are described
below. The Configuration Register is software locked.
Bit 7 - MASK - Blocks the ALERT# pin from being asserted.
„ ‘0’ (default) - The ALERT# pin is unmasked. If any bit in the status registers is set, the ALERT#
pin will be asserted (unless individually masked via the Fan Interrupt Enable Register).
„ ‘1’ - The ALERT# pin is masked and will not be asserted.
Bit 6 - DIS_TO - Disables the SMBus timeout function for the SMBus client (if enabled).
„ ‘0’ - The SMBus timeout function is enabled.
„ ‘1’ (default) - The SMBus timeout function is disabled allowing the device to be fully I²C compliant.
Bit 5 - WD_EN - Enables the Watchdog timer (see Section 4.8) to operate in Continuous Mode.
„ ‘0’ (default) - The Watchdog timer does not operate continuously. It will function upon power up and
at no other time (see Section 4.8.1).
„ ‘1’ - The Watchdog timer operates continuously as described in Section 4.8.2.
Bit 1 - DR_EXT_CLK - Enables the internal tachometer clock to be driven out on the CLK pin so that
multiple devices can be synced to the same source.
„ ‘0’ (default) - The CLK pin acts as a clock input.
„ ‘1’ - The CLK pin acts as a clock output and is a push-pull driver.
Bit 0 - USE_EXT_CLK - Enables the EMC2301 to use a clock present on the CLK pin as the
tachometer clock. If the DR_EXT_CLK bit is set, then this bit is ignored and the device will use the
internal oscillator.
„ ‘0’ (default) - The EMC2301 will use its internal oscillator for all Tachometer measurements.
„ ‘1’ - The EMC2301 will use the oscillator presented on the CLK pin for all Tachometer
measurements.
Fan Status Registers
ADDR R/W REGISTER
B7
24h
R-C
Fan Status WATCH
25h
R-C
Fan Stall
Status
-
Table 5.3 Fan Status Registers
B6
B5
B4
B3
-
-
-
-
-
-
-
-
B2
DRIVE_
FAIL
-
B1
FAN_
SPIN
-
B0
FAN_
STALL
FAN_
STALL
DEFAULT
00h
00h
SMSC EMC2301
25
DATASHEET
Revision 1.3 (05-18-11)