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TPS56C215: The minimum acceptable value of the bypass cap on the VREG

Shinya Sawamoto

Expert 5285 points

Part Number: TPS56C215

Hello application team,

Could you advice about the minimum acceptable value of the bypass cap on the VREG?
The reason why I ask it is to consider DC bias effect on ceramic caps. (e.g. the effective capacitance of 4.7uF reduces about 2uF at 4.7V bias condition)
This information is important to select a proper bypass cap.

Thanks in advance.
Shinya Sawamoto
TI Japan East area FAE

over 7 years ago

0 Edwin Zang over 7 years ago

TI__Expert 6425 points

Hello Shinya,

The VREG5 pin needs to be bypassed with a 4.7uF cap at least.

Best regards.

Edwin.

0 Shinya Sawamoto over 7 years ago in reply to Edwin Zang

TI__Expert 5285 points

Thanks, Edwin.

To be opposite, is there any maximum limitation value?
If not, I'd like to recommend 10uF bypass(with Ceff>4.7uF) to the customer instead of 4.7uF.

Regards,
Shinya Sawamoto

0 Edwin Zang over 7 years ago in reply to Shinya Sawamoto

TI__Expert 6425 points

Hello Shinya,

10uF cap is enough for VREG.

there isn't accurate maximum limitation value. If the bypass cap is too much large, the time is longer from EN ramp up to Vout ramp up.

best regards ,

edwin.