LM5149-Q1: Input Cap ESR rating

Scarlett Cao

Part Number: LM5149-Q1

Hi team,

My customer is using reverse protection diode before the Vin_emi pin, and has input cap before the diode. Does it also require this cap to have >100mohm ESR?

Thank you

Scarlett

over 1 year ago

0 Orlando Murray over 1 year ago

TI__Mastermind 22299 points

Scarlett,

Yes I think so, in normal conditions the diode current will be positive so it will effective be a short to the capacitance.

AEF may go unstable with purely capacitive impedance on that node.

Maybe you can place a placeholder ESR 0Ω and then increase as necessary.

Hope this helps,

-Orlando

0 Cheng Hui 11 months ago in reply to Orlando Murray

Prodigy 30 points

Since that node can't be purely capacitive,if a series resistor with value≥100mΩ also works？（too many input capacitor before diode for different ICs）

0 Orlando Murray 11 months ago in reply to Cheng Hui

TI__Mastermind 22299 points

Scarlett,

Yes, a spot for a series resistor for your CIN (in red) should work.

-Orlando

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LM5149-Q1: Input Cap ESR rating