RPM-Based Fan Controller with HW Thermal Shutdown
Datasheet
Chapter 5 General Description
The EMC2102 monitors three external temperature channels. Two of the external temperature
channels can employ both Beta Compensation and Resistance Error Correction for use with thermal
diodes while the third channel is hardwired to measure a discrete diode connected NPN or PNP
transistor. The temperature data is available over a standard 2-wire serial interface using SMBus read
commands. The temperature monitoring is described in more detail in Section 5.1, "Temperature
Monitoring".
The EMC2102 integrates a closed-loop RPM based Fan Control Algorithm. A host writes the desired
fan speed into a register of the EMC2102 via the SMBus and the integrated fan controller will maintain
the fan at the desired speed using fan speed feedback from the TACH output from a 3-wire fan. The
fan control algorithm controls an integrated 5V, 600mA, linear fan driver. The fan control algorithm
functionality is described in more detail in Section 5.3, "RPM based Fan Control Algorithm"
The EMC2102 provides the system with a hardware based critical/thermal shutdown function. This
critical/thermal shutdown function integrates critical signals from both the CPU and power supply and
the analog circuitry to monitor a specific temperature channel based on the system configuration. The
critical/thermal shutdown temperature threshold is configured on the PCB through a simple discrete
resistor divider. The Critical/Thermal Shutdown function is described in more detail in Section 5.7,
"Critical/Thermal Shutdown".
An example of a typical system configuration for the EMC2102 is provided in Figure 5.1.
Revision 1.95 (10-19-06)
SMSC EMC2102
DATA1S8HEET
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