EMC2103 Standard Microsystems Corporation, EMC2103 Datasheet - Page 20

• Manufacturer Part Number: EMC2103
• Description: Rpm-based Fan Controller with HW Thermal Shutdown
• Manufacturer: Standard Microsystems Corporation

Chapter 5 General Description
Revision 0.85 (01-29-08)
Optional anti-
parallel diode
Thermal
diode
The EMC2103 is an SMBus compliant fan controller with one external (EMC2103-2 offers up to three
external diode channels) and one internal temperature channels. The fan driver 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 of the BJT or transistor model for a CPU diode).
The EMC2103 allows the user to program temperatures generated from external sources to control
the fan speed. This functionality also supports DTS data from the CPU. By pushing DTS or standard
temperature values into dedicated registers, the external temperature readings can be used in
conjunction with the external diode(s) and internal diode to control the fan speed.
The EMC2103 also includes a hardware programmable temperature limit and dedicated system
shutdown output for thermal protection of critical circuitry.
Figure 5.1
CPU
shows a system diagram of the EMC2103.
* denotes EMC2103-2 only
Figure 5.1 System Diagram for EMC2103
1.2k
DN2 / DP3*
TRIP_SET
DP1
DN1
DP2 / DN3*
1.5V
EMC2103
DATASHEET
SYS_SHDN
SMDATA
SMCLK
GPIO1*
GPIO2*
ALERT
TACH
20
PWM
VDD VDD
RPM-Based Fan Controller with HW Thermal Shutdown
VDD
VDD
Interface
SMBus
Fan Drive
Circuitry
HOST
SMSC EMC2103
Datasheet