emc2105 Standard Microsystems Corp., emc2105 Datasheet - Page 61

• Manufacturer Part Number: emc2105
• Description: Emc2105 Rpm-based High Side Fan Controller With Hardware Thermal Shutdown
• Manufacturer: Standard Microsystems Corp.

ADDR
RPM-Based High Side Fan Controller with Hardware Thermal Shutdown
Datasheet
45h
SMSC EMC2105
6.21
R/W
R/W
Bit 2 - 1 - ERR_RNG[1:0] - Control some of the advanced options that affect the error window. When
the measured fan speed is within the programmed error window around the target speed, then the fan
drive setting is not updated. The algorithm will continue to monitor the fan speed and calculate
necessary drive setting changes based on the error, however these changes are ignored.
The Gain Register stores the gain terms used by the proportional and integral portions of each of the
RPM based Fan Speed Control Algorithms. These gain terms are used as the KD, KI, and KP gain
terms in a classic PID control solution.
Gain Register
1
0
0
1
1
1
0
0
1
1
Gain Register
REGISTER
ERR_RNG[1:0]
DER_OPT[1:0]
B7
-
Table 6.30 Error Range Options
Table 6.29 Derivative Options
Table 6.31 Gain Register
0
0
1
0
1
0
0
1
0
1
B6
DATASHEET
-
61
B5
GAIND[1:0]
are used effectively causing the derivative term to
Basic derivative. The derivative of the error from
to the iterative Fan Drive Register setting and is
Both the basic derivative and the step derivative
B4
the current drive setting and the target is added
the current drive setting and the target is added
Step derivative. The derivative of the error from
to the iterative Fan Drive Register setting (in
have double the effect of the derivative term
addition to proportional and integral terms)
not capped by the Fan Step Register.
B3
GAINI[1:0]
No derivative options used
0 RPM (default)
B2
OPERATION
OPERATION
100 RPM
200 RPM
(default).
50 RPM
B1
GAINP[1:0]
Revision 1.74 (05-08-08)
B0
DEFAULT
2Ah