1 Reply Latest reply on Dec 17, 2019 6:36 AM by VasanthR_91

    Analog ground with "CY8C5467LTI-LP003" ?


      i have connected ADC pins to the port P3_7 , P3_6, P3_0, P3_1 . i have some of my op-amp analog output to read at this ADC pins, now my question is as this cypress chip hardware design suggest to make separate GND for analog, i have separate GND for analog pins of Cypress chip, but my question is would i have to use the same analog ground for the ADC o/p op-amp circuit which generates the ADC output? or the general ground will be okay for it?? (i am aware that all ground are same and connected ultimately by using NET-Tie in pcb ). another question is that , i want to use this 4 above mentioned ADC pins to read in the resolution of 12-BIT ADC , (i am aware that at a time only 1 ADC can be read in this max resolution , and for multiple adc input reads i have to scan pins) this is possible by scanning interval right? please correct me if i am wrong anywhere. 

        • 1. Re: Analog ground with "CY8C5467LTI-LP003" ?

          Hi Jagrut,


          The analog ground (VSSA) is as important as any of the signals you are measuring. The trace between the PSoC VSSA pin and the system ground must be as short and low impedance as possible. Sharing this path with any component that uses even a few hundred micro-amperes can cause problems when measuring sub-milli-volt signals. An offset can translate into a measurement offset when using single-ended measurements. It is better to use the same analog ground for the opamp circuit. Kindly see Shared Return paths in the following document: PSoC® 3, PSoC 4, and PSoC 5LP Mixed-Signal Circuit Board Layout Considerations.


          Regarding ADC you can have multiple channels using 12 bit resolution. You can use the  Sequencing SAR component as it will take care of the switching between channels.


          Best Regards,