EVB-EMC2104/05 User Manual
SMSC EMC2104/05
Revision 1.0 (08-21-07)
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3 Hardware Description
3.1
Introduction
The EMC2104/05 EVB provides the means to demonstrate EMC2104/05 features and to view and
modify registers. LEDs indicate status information and test points are included to monitor system
voltages with a user provided voltmeter or oscilliscope.
3.2
EMC2104/05
The EMC2104/05 is an SMBus temperature sensor with 1 internal and 4 external sensor in an 28 pin
QFN package. Communications with the EMC2104/05 sensor is via the SMBus.
3.3
USB to SMBus Bridge
The USB to SMBus bridge is based on an 8051 microcontroller with integrated USB and SMBus
interfaces as well as internal flash and RAM. During EVB manufacture, firmware is loaded into the
bridge that provides the interface between the USB and the SMBus. Power is sourced to the
microcontroller from the USB interface for device power and communication.
3.3.1
Direct SMBus Connect Option
It is also possible to connect an external SMBus master to the EMC2104/05 EVB. A few jumper
settings are all that is required to drive the EMC2104/05 :
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Simply remove the jumpers on JP13 and connect the SMBus master to the SDA, SCL, and ALERT
pins (pins 3, 5, and 7 respectively), as well as an external supply for +3.3V (pin 1).
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The +3.3V can be supplied by the SMBus bridge by leaving the +3.3V jumper in place and retaining
the USB connection.
3.4
Connecting to Remote Diodes
This EVB is populated with jumpers (JP5, JP6, and JP8) to connect to an external diode or CPU/GPU.
If connecting to a CPU’s thermal diode, it is necessary to provide a common ground. Also, it is usually
necessary to bias the appropriate CPU Vcc plane above this common ground to avoid forward-biasing
the ESD diodes with the temperature sensor signals. Test point TP1, TP2, TP3, or TP4 can provide a
ground connection. Consult the CPU manufacturer’s datasheet for guidance on interfacing and biasing
the thermal diode. Refer to the schematic SCH-7106.pdf for details on the EVB header connections.
3.5
Resistance Error Correction (REC)
External diode 3 DN signal path has a 100 ohm series resistor to demonstrate the EMC2104/05 ’s
REC feature. The resistor may be effectively removed from the circuit by installing a jumper on JP9.
See
for details on the REC jumper settings.
3.6
Power Source
This EVB simply requires a single USB cable to operate. The USB-SMBus bridge regulates the +5V
USB power to +3.3V used by the EMC2104/05 and other EVB circuitry. If a user-provided high current
fan (>0.5A) is connected to the EVB, the user may connect a +5V power supply to terminal P3 and
move jumper JP15 to position 2-3.
3.7
Test Points
Test points are provided for the following signals and voltages:
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Power: +3.3, +5V, and Ground
