Question: We are seeing strange data values when we measure signals at a high acquisition rate (500 KHz) with our DT9834 module.  It looks like the board is "loading" down the signal.

 

Answer: Seeing the signal degrade at higher sampling rates may be related to the source impedance of the device.   The DT9834 has 100 MOhm & 100pF of impedance.   Therefore, if you connect a source device that has a 10 KOhm impedance, then the maximum allowable sample rate is approximately 110 KHz.   If however the source device has an impedance of only 500 Ohms, then the maximum potential sample rate would go to 2.2 MHz.   NOTE:   the A/D on the DT9834 can only sample at 500 KHz maximum.   
If this is a concern, then consider the DT9836 which does not have a multiplexer nor this issue.  *Created: 08/03/06