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LM5141-Q1: LM5141QRGERQ1

Roy Chan
Expert 4020 points
Part Number: LM5141-Q1

Hi Expert:

    Because We are testing  ISO16750-2 Car battery cold crank test , Vin will drop to 4V with 50mS power supply to LM5141-Q1, LM5141-Q1 Vout is design Vout=3.3V case

but we found Vout will suddenly drop to 1.6V with this conditions. May I know what's the max Duty cycle of the follow condition? can the following condition to stabilize Vout keep 3.3V when Vin =4V cold crank conditions after I design by Web bench calculator ? 

L>0.83uH

Output Capacitor: 440uF

Ccomp=10nF

Rcomp=22.6k.

Thank you 

  • 0
    TI__Guru 73102 points

    Hi Roy,

    The Fsw folds back in dropout so the duty cycle approaches 100%. Can you send the schematic and a completed quickstart calculator file. Enter the derated value for ceramic Cout.

    Note the VCC will be down to ~3.9V if Vin is 4V (boot rail will be slightly lower), so check the Miller plateau of the FETs. Send on the FET part numbers as well.

    Regards,

    Tim