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AD2S90 RDC: Unstable output on A,B encoder output pins

Question asked by engeric on Jun 14, 2012
Latest reply on Jun 29, 2012 by ShaneO

Hi Everyone.

I'm currently experimenting with an AD2S90 for resolver-digital-conversion, to provide position feedback for a motor controller. However, the A, B encoder emulation outputs are unstable and keep changing, even when the motor is not moving. Below is the screenshot of the A(ch1) and B(ch2) outputs when the resolver is stationary:

F0001TEK.JPG

 

I've connected all the pins following the example configuration in the datasheet for this device, including using an AD2S99 oscillator as the reference signal source. The resolver feedback signals appear to be correct. Below I have shown the COS-COSLO and SIN-SINLO signals.

 

TEK0000.JPG

I've also attached the schematic in PDF.

If anyone can provide some answers or has seen this problem before, I would really appreciate some comments!

 

Thanks.

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