RPM-Based Fan Controller with Multiple Temperature Zones & Hardware Thermal Shutdown
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".
Table 7.37 Derivative Options
DER_OPT[1:0]
1
0
OPERATION
0
0
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)
0
1
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.
1
1
0
1
Both the basic derivative and the step derivative
are used effectively causing the derivative term to
have double the effect of the derivative term.
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.
Table 7.38 Error Range Options
ERR_RNG[1:0]
1
0
OPERATION
0
0
1
1
0
1
0
1
0 RPM (default)
50 RPM
100 RPM
200 RPM
The Fan Configuration 2 Register is Software Locked.
SMSC EMC2113
Revision 1.2 (10-08-09)
DATA6S1HEET
SMSC [ SMSC CORPORATION ]
