Question
We got another question from our customer on AD2S1210. He would like to use one AD2S1210 to control several resolvers and use MUX select thedifferent SIN/COS input pairs. Do you think if it is possible. Anything need to be paid attention to?Another question is that it seems that the resolver SIN/COS output and the RDC input can be connected directly. So in what case, we need to adddriver or filter between the resolver output to the RDC input. Is it necessary or not?
Answer
There might be one potential issue with this approach caused by phase shift difference between these resolvers. What could be potentially done isthat as soon as the MUX position is changed digital controller on the board should reset the AD2S1210 device. Hence the RDC chip may lock to the‘new’ input signals. If this isn’t done there will be a risk of getting noise/glitch/phase shift instantly appearing on the input signal, this morethan likely will result in some faults detected by the chip. Software or Hardware reset should be enough I believe.Yes, typically there is no need to use any passive components between resolver and resolver to digital converter however in some situations RCfilters, R-dividers or protection diodes are used depending on applications. For example when the resolver analog output signal (SIN/COS) is greaterthan amplitude specification of the AD2S1210 chip simply differential resistor divider could be used. Also in case of large amount of noise presenton the SIN/COS inputs some simple RC filter could be used to dampen high frequency noise. Generally when the system is operated in very noisyenvironment some level of filtering may be required.
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