This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

AMC7834EVM: AMC7834 Electrical connection method of the Pin REF_CMP

Part Number: AMC7834EVM
Other Parts Discussed in Thread: AMC7834


  I have a few questions about ref_cmp.


 .in datasheet,the Pin REF_CMP connect a 4.7uf capacity to GND4


In AMC7834EVM user's guide(slau608b), The pin REF_CMP connect a 4.7uf capacity to GND4, and The pin REF_CMP connect to the adc reference voltage!!


3.In the actual debugging process

    in the case of case1,  Adc sampled values are error prone or sampled values cannot be read back ;

     in the case of case2, Adc sampled values are right.

4.My question 

  1.In actual design, We choose case1 or case2?

  2.case1 and case2 ,What's the essential difference? 

   Look forward to your reply ,thank your!!

  • Hi Sea Zhang,

    We recommend an 10nF cap on the REF_IN/REF_OUT connection.  A 4.7uF cap is recommended for the REF_CMP pin.  

    The AMC7834 has an internal 2.5V reference.  This can be used for the ADC by enabled the ADC reference buffer.  The internal reference can be used for the DACs by connecting the REF_OUT pin to the REF_IN pin, and by enabling the DAC Reference buffer.

    If you would like to use an external reference for the ADC, then the reference buffer should be disabled and an external reference should be connected to the REF_CMP pin.  This can be done on the EVM by shorting jumper JP6.  

    If you would like to use an external reference for the DACs, then the jumper JP10 should have pins 1 and 2 shorted.  If you want to use the internal reference for the DACs on the EVM, then short jumper 2 and 3.

    So, to use the EVM in internal reference mode, leave JP6 open, short JP10 pins 2-3, then power on the device by writing 0x02 to the e Device Configuration Register (address 0x02).  You can do this on the block diagram page by selecting the 3rd option on the power down mode field.