AD2S1210: Input connection filtering and shielding

Document created by analog-archivist Employee on Feb 23, 2016
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My AD2S1210 customer always get Sin/Cos inputs clipping error even after
lowering the gain of the EXC's buffer circuit.
He also sees noise on Sin/Cos input and he would like to add a differential
amplifier before the Sin/Cos input to reduce the noise.
Also the SINLO and COSLO will be connected to GND. Is it workable for such a
solution on noise issues?

 

Most of our customers doesn’t use active components between Resolver outputs
and RDC inputs. Noise is typically reduced by simple RC filter with cut of
frequency set around 500 kHz or even lower. You are allowed to operate the
AD2S1210 in single ended mode however you cannot connect SinLO and CosLO
terminals to GND as you definitely get clipping on the inputs. I advice to pull
up SinLO and CosLO to 2.5 V instead of GND so that the clipping issue should
not occur(i.e. through 10 kOhm resistors).

To  investigate the noise issue, ask your customer to send us the scope plots
of Sin, SinLO, Cos, CosLO, Exc and /Exc signals ? If possible please also plot
Sine and Cosine inputs differentially, all plots should be gathered at 0 and 90
degrees.

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