Question about AD5420 REFOUT voltage

Question

Hi, 
 The REFOUT voltage of AD5420 is rarely abnormal. The abnormal voltage values are as high as 5.05V~5.07V. 4 out of 500 units mounted have the abnormality. 
 What are the possible causes of the high REF voltage? 
 Attached is the circuit for AD5420, REFOUT voltage is used for Vref of an AD converter on the same board. AVDD is 24V and DVDD is not used. 
 When the AD5420s with high REFOUT were removed and other AD5420s were installed, REFOUT showed normal value. 
 
 PDF 
 Please support this case. 
 Regards, 
 Kazu

iandal · Accepted Answer

Hi Kazu 
 The reference architecture has a close relation to the capacitive load it could carry. At times, excessive capacitive load has a negative impact on the output response. I saw in your schematic that you are using 1uF bypass capacitor on refout. I'd recommend changing to the datasheet recommendation of 600nF. In my experience, 0.1uF is sufficient for the majority of references. 
 Best regards, 
 Ian

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Question about AD5420 REFOUT voltage

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