EMC2301 Standard Microsystems Corp., EMC2301 Datasheet - Page 37

• Manufacturer Part Number: EMC2301
• Description: Rpm-based Pwm Fan Controller
• Manufacturer: Standard Microsystems Corp.

ADDR
FDh
ADDR
EFh
RPM-Based PWM Fan Controller
Datasheet
SMSC EMC2301
5.19
5.20
R/W
R/W
R/W
R
RPM
The Software Lock Register controls the software locking of critical registers. This register is software
locked.
Bit 0 - LOCK - this bit acts on all registers that are designated SWL. When this bit is set, the locked
registers become read only and cannot be updated.
The Product ID Register contains a unique 8-bit word that identifies the product.
Software Lock Register
Product ID Register
REGISTER
REGISTER
Product ID
Software
‘0’ (default) - all SWL registers can be updated normally.
‘1’ - all SWL registers cannot be updated and a hard-reset is required to unlock them.
=
Lock
------------------- -
(
poles
RPM
1
)
×
=
--------------------------------- -
COUNT
3,932,160 m
------------------------------------- -
B7
B7
-
0
(
COUNT
n 1
–
Table 5.29 Software Lock Register
)
×
B6
Table 5.30 Product ID Register
---- -
m
0
1
×
B6
-
×
f
TACH
DATASHEET
B5
1
×
B5
-
60
37
B4
1
B4
-
poles = number of poles of the fan
COUNT = TACH Reading Register
measurement frequency (typically
m = the multiplier defined by the
B3
n = number of edges measured
0
B3
(typically 5 for a 2 pole fan)
-
f
TACH
value (in decimal)
RANGE bits
(typically 2)
32.768kHz)
= the tachometer
B2
B2
1
-
where:
B1
B1
-
Revision 1.2 (03-22-10)
1
LOCK
B0
B0
1
[2]
[3]
DEFAULT
DEFAULT
00h
37h