MEC1322 datasheet(301/456 Pages) MICROCHIP

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DS00001719D-page 301

MEC1322

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.

TABLE 26-12: DERIVATIVE OPTIONS

DER_OPT[1:0]

Operation

NOTE

(see

Section 26.9.7, "Fan Step

No derivative options used

PWM steps are limited to the maxi-

mum PWM drive step value in Fan

Step Register

Basic derivative. The derivative of the

error from the current drive setting and

the target is added to the iterative PWM

drive setting (in addition to proportional

and integral terms)

PWM steps are limited to the maxi-

mum PWM drive step value in Fan

Step Register

Step derivative. The derivative of the

error from the current drive setting and

the target is added to the iterative PWM

drive setting and is not capped by the

maximum PWM drive step. This allows

for very fast response times

PWM steps are not limited to the max-

imum PWM drive step value in Fan

Step Register (i.e., maximum fan step

setting is ignored)

Both the basic derivative and the step

derivative are used effectively causing

the derivative term to have double the

effect of the derivative term (default).

PWM steps are not limited to the max-

imum PWM drive step value in Fan

Step Register (i.e., maximum fan step

setting is ignored)

TABLE 26-13: ERROR RANGE OPTIONS

ERR_RNGX[1:0]

Operation

0 RPM

50 RPM (default)

100 RPM

200 RPM

Offset

05h

Bits

Description

Type

Default

Reset

Event

7:6 RESERVED

R/W

00h

5:4 GAIND[1:0]

The derivative gain term. See Table 26-14, "Gain Decode".

R/W

10h

VCC1_R

ESET

3:2 GAINI[1:0]

The integral gain term. See Table 26-14, "Gain Decode".

R/W

10h

VCC1_R

ESET

1:0 GAINP[1:0]

The proportional gain term. See Table 26-14, "Gain Decode".

R/W

10h

VCC1_R

ESET

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