LM5122: Calculate the compensation for LM5122 when combine LMP8646 to charge the super cap.

dao hop

Part Number: LM5122
Other Parts Discussed in Thread: LMP8646

Hi,

I'm designing the charging circuit with LM5122 to have Vout 60V and combine with LMP8646 to have 1.5A for charing super cap.

In the datasheet of LM5122 has the guide for calculating to select compensation network. But when using LMP8646, I think this affects the calculation for that because LMP8648 relate Vout/Vfb.

1, So first I think about is remove the compensation network. what happens with this? and LMP8646 is able work normally?

2, If my thoughts are correct, please guide to me how calculation the compensation network

Thanks and best regards,

over 1 year ago

+1 Moritz over 1 year ago

TI__Genius 16115 points

Hello,

Thank you for using E2E.

You should not remove the compensation network. This would lead to instabilities. For the calculation of the compensation network, The LMP8648 should not influence the feedback divider, as it is connected to an external supply and only adds a voltage to FB. So you can use the value of RFBT for the calculation of Rcomp.

Best regards,

Moritz

0 dao hop over 1 year ago in reply to Moritz

Prodigy 200 points

Thank you very much.

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LM5122: Calculate the compensation for LM5122 when combine LMP8646 to charge the super cap.