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AD5932 wrong output frequency

Question asked by guru on May 16, 2013
Latest reply on May 24, 2013 by guru

Hi,

 

I am using AD5932 as single frequency output, with output updated by control pin.

I am using port pin of microcontroller as SPI engine by bit banging. My earlier SPI driver was working perfectly with evaluation board, however on my actual hardware board  the same driver is not working properly. I am setting output frequency of 1 KHz, however output at AD5932 is 10 KHz.

The difference in my old hardware and new hardware is as below

 

1) In old hardware the 5V VDD is given as supply to AD5932 and all digital inputs (SDATA, CLK,FSYNC and CONTROL) are 5V level.

In new hardware  the 5V VDD is given as supply to AD5932 however all digital inputs (SDATA, CLK,FSYNC and CONTROL) are 3.5V level.

 

Will this be issue? Ideally it should work because as per datasheet, for 5V DVDD supply voltage the threshold level for digital input is 2.8V.

 

The reason for not wroking my code is related to supply voltage or is it due to timing issues? Because control word in old FW driver and new driver are same.

 

It will be great if someone can help me in finding issue

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