1 Reply Latest reply on Jun 4, 2019 1:09 AM by XiaoweiZ_71

    Difference between CSD types



          From <<Cypress’ CapSense Sigma-Delta Algorithm>>,we know CY8C21x34 has a special CSD structure with a bleed resistor. and it works very interesting

      as the document says.

           Now according to AN64846, PSOC 4S series has a fouth-generation capsense. it is called CSD_V2,isn't it?  there is no bleed resistor. i don't know how it works . who can tell something about it?

          And is capsense in CY8C21x34 the third generation capsense, with the CSD_V1 structure?



        • 1. Re: Difference between CSD types

          CapSense in CY8C21X34 is the 1st generation CSD structure (with a bleed resistor) , this structure is great invention, it provides good noise rejection performance, high SNR, and high stability.  The disadvantage of this structure is you have to change the Rbleed value to tune the sensor rawdata level, but when sensor's parasitic capacitance(CP) is very different, the Rbleed resister is hard to choose. So in next generation structure, Rbleed is replaced by IDACs, so we can tune each sensor independently.


          You can read PSoC4 CapSense Design Guide to know how the new structure works.