Dual RPM-Based PWM Fan Controller
Datasheet
Table 5.1 EMC2302 Register Set (continued)
FUNCTION
REGISTER
NAME
DEFAULT
VALUE
ADDR
R/W
LOCK
PAGE
Fan 2 Valid TACH
Count
Holds the tachometer reading that
indicates Fan 2 is spinning properly
49h
R/W
F5h
00h
00h
F8h
FFh
FFh
F8h
SWL
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Fan 2 Drive Fail
Band Low Byte
Stores the number of Tach counts used
to determine how the actual fan speed
must match the target fan speed at full
scale drive
4Ah
4Bh
4Ch
4Dh
4Eh
4Fh
R/W
R/W
R/W
R/W
R
SWL
SWL
No
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Fan 2 Drive Fail
Band High Byte
TACH 2 Target
Low Byte
Holds the target tachometer setting low
byte for Fan 2
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TACH 2 Target
High Byte
Holds the target tachometer setting high
byte for Fan 2
No
TACH 2 Reading
High Byte
Holds the tachometer reading high byte
for Fan 2
No
TACH 2 Reading
Low Byte
Holds the tachometer reading low byte
for Fan 2
R
No
Lock Register
Locks all SWL registers
Revision Registers
EF
R/W
Software Lock
00h
SWL
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FDh
FEh
FFh
R
R
R
Product ID
Manufacturer ID
Revision
Stores the unique Product ID
Stores the Manufacturer ID
Revision
36h
5Dh
80h
No
No
No
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During Power-On-Reset (POR), the default values are stored in the registers. A POR is initiated when
power is first applied to the part and the voltage on the VDD supply surpasses the POR level as
specified in the electrical characteristics. Any reads to undefined registers will return 00h. Writes to
undefined registers will not have an effect.
5.1.1
Lock Entries
The Lock Column describes the locking mechanism, if any, used for individual registers. All SWL
registers are Software Locked and therefore made read-only when the LOCK bit is set.
5.2
Configuration Register
Table 5.2 Configuration Register
ADDR
R/W
REGISTER
B7
B6
B5
B4
B3
B2
B1
B0
DEFAULT
USE_
EXT_
CLK
DR_EXT_
CLK
20h
R/W
Configuration MASK
DIS_TO WD_EN
-
-
-
40h
The Configuration Register controls the basic functionality of the EMC2302. The bits are described
below. The Configuration Register is software locked.
Bit 7 - MASK - Blocks the ALERT# pin from being asserted.
SMSC EMC2302
Revision 1.1 (10-12-09)
DATA2S5HEET
SMSC [ SMSC CORPORATION ]
