emc2104 Standard Microsystems Corp., emc2104 Datasheet - Page 21

• Manufacturer Part Number: emc2104
• Description: Emc2104 Dual Rpm-based Pwm Fan Controller With Hardware Thermal Shutdown
• Manufacturer: Standard Microsystems Corp.

Dual RPM-Based PWM Fan Controller with Hardware Thermal Shutdown
Datasheet
Chapter 5 Product Description
SMSC EMC2104
KBC
32.768KHz Clock
The EMC2104 is an SMBus compliant fan controller with up to five (up to 4 external and 1 internal)
temperature channels. It contains two fan drivers, both PWM outputs with programmable frequencies.
The fan drivers can be operated using two methods each with two modes. The methods include an
RPM based Fan Speed Control Algorithm and a direct PWM drive setting. The modes include manually
programming the desired settings or using the internal programmable temperature look-up table to
select the desired setting based on measured temperature.
The temperature monitors offer 1°C accuracy (for external diodes) with sophisticated features to
reduce errors introduced by series resistance and beta variation of substrate thermal diode transistors
commonly found in processors (including support for BJT or transistor model for CPU diodes).
The EMC2104 also includes a hardware programmable temperature limit and dedicated system
shutdown output for thermal protection of critical circuitry. Any of the three temperature channels can
be configured to measure a thermistor or voltage channel using a precision reference voltage for
reduced system complexity.
Figure 5.1
Thermal
Thermal
diode
diode
3.3V
CPU
GPU
shows a system diagram of the EMC2104.
Figure 5.1 System Diagram of EMC2104
TRIP_SET*
SMCLK
SMDATA
ALERT#
DP1*
DN1*
DP2*
DN2*
CLK_IN*
1.2k
EMC2104
DATASHEET
0.8V
VDD
3.3V
SYS_SHDN#
21
SHDN_SEL
DP3 / DN4*
DN3 / DP4*
TACH2*
PWM2*
TACH1
PWM1
3.3V
3.3V
3.3V
(optional)
APD
Circuit
Circuit
Drive
Drive
Revision 1.74 (05-08-08)
tachometer
tachometer