EVB-EMC1002/EMC1033 User Manual

Note: Asserting the Addr/Therm output low will also turn on the ARA LED on this EVB. This is because the fan driver circuit will pull down the Alert/Therm2 output when Addr/Therm is low. The SMBus ARA Protocol will not function in this case.

4.4Fan Driver

The fan driver utilizes the Alert/Therm2 and Addr/Therm outputs to drive a +5V fan to 3 different fan speeds. See the Circuit Description above for information about the fan driver. Normally, the fan driver is OFF. To turn the fan ON at low speed, the Alert/Therm2 output must be asserted low. This can be caused by dragging the High Temp Limit line below the current temperature on the Zone Temperature History graph, using the Register Manager to set the High Temp Limit value lower than the current temperature or heating the temp sensor to exceed the limit.

To turn the fan ON to high speed, the Addr/Therm output must be asserted low. This will occur when the current temperature exceeds the associated THERM limit.

Note: When Alert/Therm2 is configured as a Therm2 output, temperatures exceeding the High Temp Limit will cause it to assert, however the Low Temp Limit is ignored.

4.5SMBus Alert Protocol (ARA) Support

When the Alert/Therm2 output is asserted an SMBus Alert interrupt is generated and an indicator light will turn RED on the Register Manager panel. Press the Response button to cause RegMan to send the SMBus Alert Address to the EMC1002/1033. The EMC1002/1033 will respond with it’s SMBus address which is displayed in a text box next to the Response button on the RegMan interface. If the temperature is still above the limit, the indicator will remain lit and the Alert/Therm2 output will stay asserted. If the temperature is below the limit the indicator will turn OFF and the Alert/Therm2 output will de-assert.

4.6Resistance Error Correction (R.E.C.)

R.E.C. is normally enabled in the EMC1002/1033, however, for demonstration purposes this evaluation board uses a special test mode to disable R.E.C. To show the R.E.C. feature, remove the jumper on JP1 pins 1-2. This will insert a 100 ohm series resistor into the circuit and cause a temperature reading error of approximately 60oC. Replace the jumper and the temperature will return to its correct reading. Now enable R.E.C. by entering the value 0x0c into R.E.C. configuration register 0x53. With R.E.C. enabled, the temperature will not change when the jumper is removed.

4.7Ideality Factor Correction

The Ideality Factor can be adjusted in Ideality Factor Registers 0x27 and 0x28 (EMC1033 only). These registers will normally hold the default value which is correct for the diodes installed on the EVB. Increasing or decreasing the value will cause a corresponding change in the temperature reading.

4.8Anti-Parallel Diode (EMC1033 only)

The EMC1033 supports an Anti-Parallel Diode (APD) configuration, where 2 diodes share the same DP and DN lines but are in opposite polarity to each other. The Remote2 diode can be disconnected from the circuit by removing one or both jumpers on JP1 pins 3-4 and 5-6. The APD function is normally enabled on device power-up; the function can be disabled by writing a “1” to Configuration Register 0x09, bit 0.

Revision 1.1 (12-14-06)

SMSC EMC1002/EMC1033

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