emc2305 Standard Microsystems Corp., emc2305 Datasheet - Page 18

• Manufacturer Part Number: emc2305
• Description: Multiple Rpm-based Pwm Fan Controller For Five Fans
• Manufacturer: Standard Microsystems Corp.

Chapter 4 Product Description
Revision 1.2 (03-22-10)
4.1
MCU
The EMC2305 is an SMBus compliant fan controller with five programmable frequency PWM fan
drivers. The fan drivers can be operated using two modes: the RPM-based Fan Speed Control
Algorithm or the direct fan drive setting.
Figure 4.1
The EMC2305 has two modes of operation for each fan driver. Each mode of operation uses the Ramp
Rate control and Spin Up Routine.
1. Direct Setting Mode - in this mode of operation, the user directly controls the fan drive setting.
Fan Control Modes of Operation
Updating the Fan Driver Setting Register (see
Ramp Rate control is optional and enabled via the EN_RRC bits.
shows a system diagram of the EMC2305.
tachometer
tachometer
Circuit
Circuit
Drive
Drive
Figure 4.1 System Diagram of EMC2305
3.3V
SMCLK
SMDATA
ALERT#
TACH1
PWM1
TACH2
PWM2
GND
ADDR_SEL
DATASHEET
EMC2305
VDD
18
Section
Multiple RPM-Based PWM Fan Controller for Five Fans
TACH5
TACH3
TACH4
PWM5
PWM3
PWM4
CLK
5.7) will instantly update the PWM fan drive.
32.768KHz Clock
Input or Output
Circuit
Circuit
Circuit
Drive
Drive
Drive
tachometer
tachometer
tachometer
SMSC EMC2305
Datasheet