EMC2103-2-AP-TR Standard Microsystems (SMSC), EMC2103-2-AP-TR Datasheet - Page 63

• Manufacturer Part Number: EMC2103-2-AP-TR
• Description: CLOSED LOOP RPM FAN CONTROLLER
• Manufacturer: Standard Microsystems (SMSC)

ADDR
50h
RPM-Based Fan Controller with HW Thermal Shutdown
Datasheet
SMSC EMC2103
6.31
6.32
ADDR
4Eh
4Fh
R/W
R/W
RPM
R/W
If the algorithm is enabled then setting the TACH Target Register to FFh will disable the fan driver (set
the PWM duty cycle to 0%). Setting the TACH Target to any other value (from a setting of FFh) will
cause the algorithm to invoke the Spin Up Routine after which it will function normally.
The TACH Reading Register contents describe the current tachometer reading for the fan. By default,
the data represents the fan speed as the number of 32kHz clock periods that occur for a single
revolution of the fan.
Equation [3]
[4]
measuring 5 edges, with a frequency of 32.768kHz.
See
The Look Up Table Configuration Register controls the setup information for the temperature to fan
drive look up table.
Bit 7 - USE_DTS_F1 - This bit determines whether the Pushed Temperature 1 Register is using DTS
data.
TACH Reading Register
Look Up Table Configuration Register
Configuration
R
R
REGISTER
shows the simplified translation of TACH Reading Register count to RPM assuming a 2-pole fan,
‘0’ (default) - The Pushed Temperature 1 Register is not using DTS data. The contents of the
Pushed Temperature 1 registers is standard temperature data.
=
Appendix B
LUT
------------------- -
(
poles
RPM
REGISTER
1
Fan TACH
Fan TACH
Low Byte
shows the detailed conversion from TACH measurement (COUNT) to RPM while
)
=
×
for a table enumerating the RPM to TACH conversion for the default settings.
--------------------------------- -
COUNT
3,932,160 m
------------------------------------- -
USE_D
Table 6.49 Look Up Table Configuration Register
TS_F1
B7
(
COUNT
n 1
–
Table 6.48 TACH Reading Register
4096
)
×
B7
16
---- -
m
×
1
USE_D
TS_F2
×
B6
1,966,080
2048
B6
DATASHEET
8
LUT_L
OCK
1024
B5
B5
63
4
512
RPM /
B4
PWM
2
B4
poles = number of poles of the fan
COUNT = TACH Reading Register
256
m = the multiplier defined by the
B3
n = number of edges measured
1
B3
-
value (in decimal)
128
TEMP3
_CFG
B2
-
RANGE bits
B2
(typically 2)
(typically 5)
where:
B1
64
-
B1
-
Revision 0.88 (06-30-08)
B0
32
-
TEMP4
_CFG
B0
DEFAULT
FFh
F8h
Equation
DEFAULT
[3]
[4]
00h