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PSoC™ 4 Forum Discussions

NaMo_1534561
Level 5
Level 5
100 replies posted 100 sign-ins 50 replies posted

Hello,

Customers are trying to place ferrite beads in the VDD and GND wiring as a noise countermeasure on the power supply line where switching power supplies are generated.

A bypass capacitor is already placed in the circuit. (0.1uF and 1uF for Vdd, 0.1uF for Vccd)

Are there any cautions on the circuit layout regarding the placement of bypass capacitors and ferrite beads?

MPN : CY8C4014SXI-420

Best Regards,

Naoaki Morimoto

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1 Solution

Yes, you should place Filter Capacitor to Controller closer as possible.

There is no spec about the actual value which is better to be close from Controller.

Aiko Ohtaka
Infineon Technologies

View solution in original post

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5 Replies
TakashiM_61
Moderator
Moderator
Moderator
1000 replies posted 500 solutions authored 750 replies posted

Have you checked PSoC hardware related application notes?

AN88619 - PSoC 4 Hardware Design Considerations

https://japan.cypress.com/documentation/application-notes/an88619-psoc-4-hardware-design-considerati...

AN80994 - Design Considerations for Electrical Fast Transient (EFT) Immunity

https://japan.cypress.com/documentation/application-notes/an80994-design-considerations-electrical-f...

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Hello TakashiM_61-san,

Yes, I referred to "AN85951 PSoC4 and PSoC6 MCU CapSense Design Guide" and "AN80994 Design Considerations for Electrical Fast Transient (EFT) Immunity".

I can refer to "Figure 15. Filters Near the Supply Pins of a Controller" of AN80994.

Should the Bypass Capacitor be placed closest to VDD / VSS, with L1, L2 and C1, C2 placed next?

How far do these components need to fit from the IC?

PSoC4000 Datasheet - Bypass Cap example.PNGFilter on Supply Pins.PNG

Best Regards,

Naoaki Morimoto

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Hello,

If there are no rules regarding the layout of bypass capacitors and ferrite beads, I will tell the customer the following:

-Place the bypass capacitor within 10 mm from the VDD / VSS pin of PSoC.

-Next, insert the ferrite beads into the VDD / VSS line.

If you are satisfied with this content, please close this case.

Best Regards,

Naoaki Morimoto

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Yes, you should place Filter Capacitor to Controller closer as possible.

There is no spec about the actual value which is better to be close from Controller.

Aiko Ohtaka
Infineon Technologies
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Hello AikoO_51-san,

Thank you for your reply.

Please close this case.

Best Regards,

Naoaki Morimoto

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