LM5085EVAL: Selection of diode current ratings

OverAgent712

Part Number: LM5085EVAL
Other Parts Discussed in Thread: LM5148, LM5085, LM5149

Tool/software:

Hello,

In the EVM the output current is 5A, whereas the diode used is rated for 20A. What was the reason behind it ?

What was the worst case current and how was it found ?

over 1 year ago

0 EricLee over 1 year ago

TI__Guru 59261 points

Hello

It is not recommended to use LM5085 to handle 10A. Please consider to use synchronous buck controllers like as LM5148 or LM5149.

Non-synchronous buck converter is usually used to handle up to 5A due to the thermal limitation of the components.

-EL

0 OverAgent712 over 1 year ago in reply to EricLee

Intellectual 470 points

Hello,

Okay, but that was not my question. I need to know the reason why the diode with that current ratings was selected for the 5A output.

0 EricLee over 1 year ago in reply to OverAgent712

TI__Guru 59261 points

Hello

That's a headroom. Conservative engineers want to have enough margin. Aggressive engineers want to have minimum headroom.

-EL

0 OverAgent712 over 1 year ago in reply to EricLee

Intellectual 470 points

Hello,

Okay, what should the minimum rating be for it, Lets say for 10A output what should the headroom be for the diode ratings?

0 EricLee over 1 year ago in reply to OverAgent712

TI__Guru 59261 points

Hello

10A is the average buck converter output current ? peak diode current ? RMS diode current ?

The example abs max specification is here

-EL

Power management

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LM5085EVAL: Selection of diode current ratings