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Do you really need that capacitor ? | Cypress Semiconductor

Do you really need that capacitor ?

Summary: 1 Reply, Latest post by U2 on 08 Jun 2011 02:48 AM PDT
Verified Answers: 0
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Rocketmagnet's picture
131 posts

Hi all,

I'm laying out a very space constrained PCB with a CY8C3446LTI-073. It's a 15mm diameter disc, which leaves very little room for other components. One thing I have noticed is that the device requires many capacitors (9). On such a tiny board, these start to become a real problem.

Are all of those capacitors really necessary? Can I get away without some of them? Especially considering that the board is so small, and none of the pins are far from the linear regulator's output capacitor.

For example, if I'm not using any of P0 for digital IO, can I drop the capacitor on the VDDIO0 pin?


Many thank

Hugo Elias


uday's picture
Cypress Employee
569 posts

For any PSoC3 chip it is always recommended to have Bypass Capacitors are at VDDIO0,VDDIO1,VDDIO2,VDDIO3,VDDA,VDDD and Storage capacitors at VDDD,VDDA. Capacitors are also necessary to be present at VCCA and VCCD to stabilise core voltages. You can avoid using the Bypass capacitors on VDDIOs,VDDD and VDDA as long as the voltage that is appearing at these terminals is guaranteed to be stable. However the bulk capacitors on VDDA,VDDD, VCCA and VCCD may be necessary. 

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