EMC2102-DZK-TR SMSC, EMC2102-DZK-TR Datasheet - Page 21

• Manufacturer Part Number: EMC2102-DZK-TR
• Description: Industrial Temperature Sensors RPM Fan Contrllr
• Manufacturer: SMSC

Specifications of EMC2102-DZK-TR

• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

RPM-Based Fan Controller with HW Thermal Shutdown
Datasheet
SMSC EMC2102
5.2
5.3
Fan Driver Setting (read / write)
EDGES[1:0]
-
-
-
-
-
Valid TACH Count
-
TACH Reading
The EMC2102 has two modes of operation for the High Side Fan Driver. They are:
1. Manual Mode - in this mode of operation, the user directly controls the fan drive setting. Updating
2. Using RPM based Fan Control Algorithm - in this mode of operation, the user determines a target
The EMC2102 includes a RPM based Fan Control Algorithm that controls an integrated linear High
Side Fan Driver. This fan control algorithm automatically approaches and maintains the system’s
desired fan speed to an accuracy directly proportional to the accuracy of the clock source. Figure 5.2,
"RPM based Fan Control Algorithm" shows a simple flow diagram of the RPM based Fan Control
Algorithm operation.
The desired TACH count is set by the user inputting the desired number of 32.768KHz cycles that
occur per fan revolution. The user may change the target count at any time. The user may also set
the target count to FFh in order to disable the fan driver for lower current operation.
For example, if a desired RPM rate for a 2-pole fan is 3000RPMs, then the user would input the
hexidecimal equivalent of 655 (29h in the TACH Target Register). This number represents the number
of 32.768KHz cycles that would occur during the time it takes the fan to complete a single revolution
when it is spinning at 3000RPMs (see
Fan Control Modes of Operation
RPM based Fan Control Algorithm
The Manual Mode is enabled by clearing the EN bit in the Fan Configuration Register (see
Section
Whenever the Manual Mode is enabled the current drive will be changed to what was last written
into the Fan Driver Setting Register.
Setting the drive value to 00h will disable the High Side Fan Driver for lower power operation.
the Fan Driver Setting Register (see
TACH count and the drive setting is automatically updated to achieve this target speed. The
algorithm uses the Spin Up Routine and has user definable ramp rate controls.
MANUAL MODE
6.13).
Table 5.1 Fan Controls Active for Operating Mode
DATASHEET
Equation [4]
Section
21
Fan Driver Setting (read only)
EDGES[1:0]
(Fan Configuration)
UPDATE[2:0]
(Fan Configuration)
LEVEL
(Spin Up Configuration)
SPINUP_TIME[1:0]
(Spin Up Configuration)
Fan Step
Fan Minimum Drive
Valid TACH Count
TACH Target
TACH Reading
6.12) will instantly update the fan drive.
in
Section
6.19).
ALGORITHM
Revision 2.02 (05-17-07)