MEC1322 Datasheet, PDF (301/456 Pages) Microchip Technology – Keyboard and Embedded Controller for Notebook PC

MEC1322
TABLE 26-12: DERIVATIVE OPTIONS
DER_OPT[1:0]
1
0
Operation
NOTE
(see Section 26.9.7, "Fan Step
Register")
0
0
No derivative options used
PWM steps are limited to the maxi-
mum PWM drive step value in Fan
Step Register
0
1
Basic derivative. The derivative of the PWM steps are limited to the maxi-
error from the current drive setting and mum PWM drive step value in Fan
the target is added to the iterative PWM Step Register
drive setting (in addition to proportional
and integral terms)
1
0
Step derivative. The derivative of the PWM steps are not limited to the max-
error from the current drive setting and imum PWM drive step value in Fan
the target is added to the iterative PWM Step Register (i.e., maximum fan step
drive setting and is not capped by the setting is ignored)
maximum PWM drive step. This allows
for very fast response times
1
1
Both the basic derivative and the step PWM steps are not limited to the max-
derivative are used effectively causing imum PWM drive step value in Fan
the derivative term to have double the Step Register (i.e., maximum fan step
effect of the derivative term (default). setting is ignored)
TABLE 26-13: ERROR RANGE OPTIONS
ERR_RNGX[1:0]
1
0
Operation
0
0
0
1
1
0
1
1
0 RPM
50 RPM (default)
100 RPM
200 RPM
26.9.5 GAIN REGISTER
The Gain Register The Gain Register stores the gain terms used by the proportional and integral portions of the RPM
based Fan Control Algorithm. These terms will affect the FSC closed loop acquisition, overshoot, and settling as would
be expected in a classic PID system.
This register only applies if the Fan Speed Control Algorithm is used.
Offset ^05h
Bits
Description
7:6 RESERVED
5:4 GAIND[1:0]
The derivative gain term. See Table 26-14, "Gain Decode".
3:2 GAINI[1:0]
The integral gain term. See Table 26-14, "Gain Decode".
1:0 GAINP[1:0]
The proportional gain term. See Table 26-14, "Gain Decode".
Type
R/W
R/W
R/W
R/W
Default
00h
10h
10h
10h
Reset
Event
-
VCC1_R
ESET
VCC1_R
ESET
VCC1_R
ESET
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DS00001719D-page 301