EMC2113 datasheet(61/85 Pages) SMSC

61 / 85 page

RPM-Based Fan Controller with Multiple Temperature Zones & Hardware Thermal Shutdown

Datasheet

SMSC EMC2113

Revision 1.2 (10-08-09)

DATASHEET

Bit 5 - GLITCH_EN - Disables the low pass glitch filter that removes high frequency noise injected on

the TACH pin.

‘0’ - The glitch filter is disabled.

‘1’ (default) - The glitch filter is enabled.

Bits 4 - 3 - DER_OPT[1:0] - Control some of the advanced options that affect the derivative portion of

the RPM-based Fan Speed Control Algorithm as shown in Table 7.37, "Derivative Options".

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 Fan Configuration 2 Register is Software Locked.

Table 7.37 Derivative Options

DER_OPT[1:0]

OPERATION

No derivative terms used

Basic derivative. The derivative of the error from

the current drive setting and the target is added

to the iterative Fan Drive setting (in addition to

proportional and integral terms - default)

Step derivative. The derivative of the error from

the current drive setting and the target is added

to the iterative Fan Drive setting and is not

capped by the maximum Fan Step Register

setting.

Both the basic derivative and the step derivative

are used effectively causing the derivative term to

have double the effect of the derivative term.

Table 7.38 Error Range Options

ERR_RNG[1:0]

OPERATION

0 RPM (default)

50 RPM

100 RPM

200 RPM

EMC2113 Datasheet(PDF) 61 Page - SMSC Corporation