EMC2303-1-KP-TR Standard Microsystems (SMSC), EMC2303-1-KP-TR Datasheet - Page 18

• Manufacturer Part Number: EMC2303-1-KP-TR
• Manufacturer: Standard Microsystems (SMSC)

Specifications of EMC2303-1-KP-TR

• Operating Supply Voltage (typ): 3.3V
• Operating Supply Voltage (min): 3V
• Operating Supply Voltage (max): 3.6V
• Operating Temp Range: -40C to 125C
• Operating Temperature Classification: Automotive
• Mounting: Surface Mount
• Pin Count: 12
• Lead Free Status / RoHS Status: Compliant

Revision 1.2 (03-22-10)
4.2
4.3
Fan Driver Setting (read / write)
EDGES[1:0]
-
UPDATE[2:0]
(Fan Configuration)
LEVEL
(Spin Up Configuration)
SPINUP_TIME[1:0]
(Spin Up Configuration)
Fan Step
-
Valid TACH Count
-
TACH Reading
-
The EMC2303 supports 3 PWM output drivers. Each output driver can be configured to operate as an
open-drain (default) or push-pull driver and each driver can be configured with normal or inverse
polarity. Additionally, the PWM frequencies are independently programmable with ranges from 9.5Hz
to 26kHz in four programmable frequency bands.
The EMC2303 includes 3 RPM-based Fan Speed Control Algorithms. Each algorithm operates
independently and controls a separate fan driver. Each algorithm is controlled manually (by setting the
target fan speed).
This fan control algorithm uses Proportional, Integral, and Derivative terms to automatically approach
and maintain the system’s desired fan speed to an accuracy directly proportional to the accuracy of
the clock source.
The desired tachometer count is set by the user inputting the desired number of 32.768kHz cycles that
occur per fan revolution. This is done by manually setting the TACH Target Register. 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 3000 RPMs, then the user would input the
hexidecimal equivalent of 1296 (51h 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.
PWM Fan Driver
RPM-based Fan Speed Control Algorithm (FSC)
DIRECT SETTING MODE
Table 4.1 Fan Controls Active for Operating Mode
DATASHEET
18
Fan Driver Setting (read only)
EDGES[1:0]
(Fan Configuration)
RANGE[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 (read / write)
TACH Reading
DRIVE_FAIL_CNT[1:0] and Drive Band Fail Registers
Multiple RPM-Based PWM Fan Controller for Three Fans
FSC MODE
SMSC EMC2303
Datasheet