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Input Resistance of AD7656A-1

Question asked by zeclayte on Apr 21, 2014
Latest reply on Apr 21, 2014 by harryh

Dear ADI Technical Support,

 

We are designing a buffer to drive the analog inputs of AD7656A-1 (250ksps, 6-channel, simultaneous sampling, bipolar, 16-bit ADC). And we have following questions regarding its analog inputs.

 

1. What's the input resistance of the analog input? (The spec only specifies the input capacitance to be 14pA and input leakage current to be +-1uA.)

2. In the 'Analog Input' section of 'Converter Details', it's mentioned that the sampling capacitance is 10 pF and the pin capacitance is roughly 4pF. Does this mean the input cap of the ADC is 14pF during tracking mode and 4pF during hold mode?

 

We look forward to hearing from you. Thank you very much!

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