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TPS65177A: TPS65177A SW Resistor

Yang Wu
Expert 3060 points
Part Number: TPS65177A

Hi Team,

I open this threat and also involve customer to discuss here. Customer will add more comments. 

Customer wants to improve the output current of VGL path and changes the SW resistor from 2.2ohm to 1ohm, but have oscillation issue. the waveforms are shown as below.

Do you know how this can happen and have to solve it?

thanks a lot.

Best regards,

yang

  • 0
    TI__Mastermind 18550 points

    Hi Yang,

    This resistor isolates the SW node from higher charge pump capacitances and smaller resistor value do have the potential for the artifacts such as the one customer is noticing. Switching at SW node has high rise/fall  time and even small capacitive paths can introduce disturbance and degrade the waveform. Customer can achieve somewhat higher load current by increasing the value of the 470nF flying capacitor to 1uF instead of lowering this resistor's value.

    Kind Regards,

    Liaqat