TPS54302: can smaller inductor be used?

Given Ding

Part Number: TPS54302

Hi Team,

can smaller inductor such as 1uH/1.5uH be used?

I see it is peak current mode, inductor should not affect the loop, so loop compensation should not be the problem. Then is there other limit on reducing inductor if current ripple can be accepted?

Also, the cap should be limited due to loop, right? but if inductor is smaller, we may use larger Cout to reduce Vout ripple, how to choose the Cout ? maybe I need to know the position of internal zero. Thanks.

BRs

Given

over 3 years ago

0 Young Zhao over 3 years ago

TI__Genius 11040 points

Hi Given,

1. Normally we would set the inductor current ripple K between 0.2~0.6, to limit the inductor selection

2. Cap is related with output voltage ripple and loop , cap selection is a trade off decision. You can check below app notes for reference.

Stability Analysis & Design of Internally-Compensated Peak Current Mode: Part I Stability Analysis & Design of Internally-Compensated Peak Current Mode: Part II

BRs,

Young

0 Given Ding over 3 years ago in reply to Young Zhao

TI__Genius 10465 points

Hi Young,

Thanks for your reply.

1. if we can accept large ripple, then can we just use small inductor which provide >0.6 K? Thanks.

BRs

Given

+1 Young Zhao over 3 years ago in reply to Given Ding

TI__Genius 11040 points

Hi Given,

Not suggest to do like this, as it would affect the inductor performance, like inductor derating at Ipeak current. It would also more easily to trigger OC/NOC protection.

Or you need to select a much higher Idc and Isat inductor and additional output cap, while also pls not to trigger OCP during operation .

BRs,

Young

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TPS54302: can smaller inductor be used?