PSOC4 Analog Ground

[joli_601446]

Hello, I am using the CY8C4244PVI-442 PSOC MCU 28SSOP and I don't see in the Datasheet where there is a connection to Digital Ground. I have decided to power the MCU using a 5V supply that I use for other 5V digital devices.

Is it okay for me to tie VSS to a Digital Ground?

If I tie VSS to Analog Ground should I use a Digital Ground for the VDD bypass caps?

If you have any comments on how I am powering the MCU please let me know.

Thank you

Joe

[BragadeeshV]

Hi joli_601446​,

Please note that the PSoC 4 parts that are available in the 28-pin SSOP package have the VSSD and VSSA supply pins combined into a single VSS pin to save pins. Also, the VDDA and VDDD pins are combined into a single VDD pin. This 28-pin SSOP package should be avoided when the maximum analog performance is required when several GPIO pins are used to drive fast low-impedance loads.

The VDD decoupling capacitors should be connected between the VDD and VSS pins only. It is better if you connect your digital ground to this VSS pin.

Please refer app note PSoC® 3, PSoC 4, and PSoC 5LP Mixed-Signal Circuit Board Layout Considerations that provides sample layout examples for PSoC 4 SSOP packages.

https://www.cypress.com/file/136286/download

Regards,

Bragadeesh

[joli_601446]

Hello, thank you for responding to my message. I tied the Analog Ground with the Digital Ground at the Power Input connector. With that being said is it okay to tie VDDQ to Digital Ground as shown in my attached graphic? Is it okay to tie VSS to Digital Ground as shown in the above graphic? I am not driving any analog loads only digital loads. I'm controlling the enable pin on some switching power supplies and also interfacing with a buffer driver to turn on some LEDS. Basically I use the PSOC4 to sequence the power rails for an FPGA.

Thank you

[BragadeeshV · Accepted solution]

Hi joli_601446​

Since you are using PSoC 4 only for digital purpose it is better to connect the PSoC 4 VSS pin to the digital ground itself.

Regards,

Bragadeesh

[joli_601446]

Thank you very much.

Joe