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AD9826 - Single Channel SHA-Mode.

Question asked by mrohit2011 on Nov 16, 2017
Latest reply on Nov 26, 2017 by mrohit2011

We have interfaced AD9826 with microcontroller for DC test Voltage measurement. ADC Clock is 1Mhz and timing's for ADCCLK and CDS2 clock is provided into the attachment. The ADC processor is configured into SHA Mode to read the dc voltage from voltage source.

To test, Analog input (0-3V) is provied to VINR using potentiometer.

 

Settings for registers are as follows,

Configuration Register -->

Input Range : 4V,

Internal Vref : Disabled(Also tried by Enabling this),

3CH Mode : Off,

SHA Mode Enabled,

Input Clamp Bias : 3V,

 

Mux Configuration Register -->

Only Red Channel selected.(Analog Input is given to this pin).

 

ADC Clock and CDS Clock timings waveforms are generated as below,

Problem : 

Data read from data lines is not as per the voltage applied to VINR input. 

Since applied input varies from 0 to 2V, the data output should vary from 0x0000 to 0xffff respectively. But the output is read as 0x0000,  0xff00, 0x0A0A or some random values.

So is it due to improper timings , wrong settings or any other reason.

Please help us with this issue.

 

Thanks and Best Regards,.

Rohit M.

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