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TPS92690-Q1: TPS92690PWPR/NOPB IS pin has Ringingeffect

LeoChen
Intellectual 560 points
Part Number: TPS92690-Q1
Other Parts Discussed in Thread: TPS92690

Hi, 

We find TPS92690PWPR/NOPB PIN has Ringingeffect, want to reduce it.

And want to know what cause it?

 

Design feature:

Vin 16.8v

Vout 40v

F=402Khz

Rt=105k

PWM=3Khz

  • 0
    TI__Mastermind 18890 points

    Hello,

    There is NOPB pin on the TPS92690.  I assume it's the IS pin on the part which is the switch node for the Boost configuration.  What you are seeing is the regulator is operating in discontinuous mode.  This when the FET is on the current will charge in the inductor and when the FET turns off then the switch node goes high until the diode conduct and discharge the current to the output.  When the current reaches zero then you will see this ringing.  This is normal for the boost switch node to do this in discontinuous mode operation.  The ringing is related to the inductor and parasitic capacitance at the switch node and if it does not cause a problem then you don't do anything about it.

    Thanks Tuan