EMC2305_11 Datasheet, PDF (1/56 Pages) SMSC Corporation – Multiple RPM-Based PWM Fan Controller for Five Fans

EMC2305
Multiple RPM-Based PWM Fan Controller
for Five Fans
PRODUCT FEATURES
Datasheet
General Description
The EMC2305 is an SMBus compliant fan controller with
up to five independently controlled PWM fan drivers.
Each fan driver is controlled by a programmable
frequency PWM driver and Fan Speed Control algorithm
that operates in either a closed loop fashion or as a
directly PWM-controlled device.
The closed loop Fan Speed Control algorithm (FSC) has
the capability to detect aging fans and alert the system.
It will likewise detect stalled or locked fans and trigger
an interrupt.
Additionally, the EMC2305 offers a clock output so that
multiple devices may be chained and slaved to the
same clock source for optimal performance in large
distributed systems.
Applications
„ Servers
„ Projectors
„ Industrial and Networking Equipment
„ Notebook Computers
Features
„ Five Programmable Fan Control circuits (EMC2305)
— 4-wire fan compatible
— High speed PWM (26 kHz)
— Low speed PWM (9.5Hz - 2240 Hz)
— Optional detection of aging fans
— Fan Spin Up Control and Ramp Rate Control
— Alert on Fan Stall
— Up to 3 Selectable Default Fan Speeds
„ Watchdog Timer
„ RPM-based fan control algorithm
— 0.5% accuracy from 500 RPM to 16k RPM (external
crystal oscillator)
— 1% accuracy from 500 RPM to 16k RPM (internal clock)
„ SMBus 2.0 Compliant
— Up to 6 selectable SMBus addresses
— SMBus Alert compatible
„ CLK Pin can provide a clock source output
„ Available in a 16-pin 4mm x 4mm QFN Lead-free
RoHS Compliant package
Block Diagram
CLK
TACH1
TACH2
TACH3
TACH4
TACH5
PWM1
PWM2
PWM3
PWM4
PWM5
Tach
Measurement
Tachometer
Limit
Registers
PWM
Drivers
Fan Speed Control Algorithm
Fan Speed Control Algorithm
Fan Speed Control Algorithm
Fan Speed Control Algorithm
Fan Speed Control Algorithm
SMBus
Slave
Protocol
ADDR_SEL
SMCLK
SMDATA
ALERT#
SMSC EMC2305
DATASHEET
Revision 1.3 (05-18-11)