LM25149-Q1: I would like to know rated current of the flywheel diode in LM25149.

yuka Ouchida

Prodigy 120 points

Part Number: LM25149-Q1
Other Parts Discussed in Thread: LM25149

Hi team,

The block diagram in LM25149 data sheet states that the flywheel diode (the diode between VCC and CBOOT) is integrated.

I would like to know the MAX value of rated current of the flywheel diode.

Please let me know for reference.

regards,

8 months ago

0 Orlando Murray 8 months ago

TI__Mastermind 22299 points

Yuka,

It should be rated for the VCC current limit, so 170mA continuous.

We don't characterize the peak currents that much.

Hope this helps,

-Orlando

0 yuka Ouchida 8 months ago in reply to Orlando Murray

Prodigy 120 points

Hi Orlando,

Thanks for the reply.
I have more question,

I think that the flywheel diode will only have current flow during the dead time. Is it right?
Even if the power supply output current is large, is it necessary to be able to flow a large amount of current from the flywheel diode?
What current load do you test at as a power supply?

regards,

0 David Baba 8 months ago in reply to yuka Ouchida

TI__Mastermind 31110 points

HEllo Yuka,

Current will flow in the boot diode during the 1-D period. high currents from the supply do not flow through the boot diode.

the Vsupply current needs to be greater than the current computed from PIN/Vinmin where PIN = POUT/Efficiency.

Hope this helps.

David.

0 yuka Ouchida 8 months ago in reply to David Baba

Prodigy 120 points

Hi Orlando,

Thanks for the reply.
I have more question,

I would like to say that there is no problem with the current that the flywheel diode can flow through is 170 mA.

Is there a numerical basis?
Please tell me if there is a calculation method.

regards,

0 Orlando Murray 8 months ago in reply to yuka Ouchida

TI__Mastermind 22299 points

Yuka,

This is not really a "flywheel" diode, but the boot diode should be able to tolerate 170mA.

There is no calculation for this, this is based on electrical specs in the EC table, mainly VCC current limit.

-Orlando

0 yuka Ouchida 8 months ago in reply to Orlando Murray

Prodigy 120 points

Hi Orlando,

Thanks for the reply.

I understood that the rated current of the boot diode was not a problem because it could withstand the constant flow of the current limit current of the VCC power supply of the internal LDO.
Is it right?
Thank you for letting me check it again and again.

regards,

+1 Orlando Murray 8 months ago in reply to yuka Ouchida

TI__Mastermind 22299 points

Yuka,

Yes that is correct.

-Orlando

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LM25149-Q1: I would like to know rated current of the flywheel diode in LM25149.