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Original question:

TPS65218: Issue with DCDC4 startup

TPS65218: Issue with DCDC4 startup

John11513
Expert 5720 points
Part Number: TPS65218


Hi,

My customer reported similar problem with DCDC4. We tried to connect a 220pF cap from L4A pin to ground. However it cannot always help. Some device can work with this work around while some others cannot. One of device can start up but automatically shutdown-and-startup again repeatedly each several seconds.

Attached is customer's schematic and PCB file. What should we do with this problem?

Thank you,

JohnTPS65218Design.pdfMASTERMODULE_TI.brd

  • 0
    TI__Mastermind 30310 points

    This issue was resolved by Nick Jakse in multiple way:

    "Our recommended work around is to either place a shottky diode or a 100pf-300pF capacitor from ground to the L4A pin. A better ground connection to the DCDC4 output cap with multiple vias connecting to the powerpad, and putting the output cap close to the PMIC on the same side of the board can also help."

    1. 100-300pF capacitor, or
    2. Schottky diode, AND
    3. improved layout at the DCDC4 output cap (multiple vias & optimal component placement)

    Did you and your customer try all of these solutions or only solution #1 using a 200pF capacitor? 

    Did you trying increasing this capacitance to 300pF?

    Please try all suggestions made by Nick in the previously answered e2e question.