K70 bypass capacitors for DDR_VDD

[isaotakashima]

Our customer make the K70 board refer schematics of the TWR-K70F120M.

They believe that the following bypass capacitors of the K70's DDR_VDD and DDR2 Memory's VDD, VDDQ are listed in page 10 of the TWR-K70F120M schematics. And these bypass capacitors located between K70 and DDR2 memory.

- 0.1uF x 16pcs

- 47uF x 1pc.

Are they correct?

Should they add more bypass capacitors?

Please advise as soon as possible.

Best regards,

Takashima

[Kan_Li]

Hi Isao Takashima,

Those are the bypass caps for the 1.8V DDR supply. Some of them are placed near the processor and some near the memory. Bypass caps should be should be placed as close as possible to the components that are using the power supplies.

The bypass caps serve two purposes--meeting instantaneous current demands and reducing high frequency noise. The exact bypass needed is really dependent on the specifics of the board design. The customer can follow what we've done as a general guideline, but really they need to evaluate their own design to determine if additional or maybe less bypass is needed.

Hope that helps,

Have a great day,
Kan

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