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TLV62130: SW voltage waveform behavior

Stephane breysse
Prodigy 30 points
Part Number: TLV62130

Hello,

I a design, a TLV62130 is used to create a 3.2V voltage supply.

Probing the SW pins I see the waveform below during operation.

I am wondering why there is this sine waveform before the square pulse. 

Any idea ? 

Best regards,

Stéphane

  • 0
    TI__Intellectual 1610 points

    Stephan,

    It appears to me that your design is running in "Power Save Mode"  (Discontinuous mode) and the sine wave you are seeing on the SW pin above is the expected behavior as the internal low side FET is disabled when the inductor current drops to zero.

    You can see this same behavior illustrated in figure 35 in the datasheet, although the duty cycle is less than in your design.

    Sincerely,

    -Matt

  • 0 in reply to Matthew Murdock
    Prodigy 30 points

    Hello Mat,

    Thank you for your answer Matt.

    I will add a load to try moving out of power save mode.

    Regards,

    Stéphane

  • 0 in reply to Stephane breysse
    TI__Intellectual 1610 points

    Stephane,

    Please be aware that there are traditionally no problems with having the DC/C regulator run in discontinuous mode.  The device is specifically design to run in this mode to maximize the efficiency at light loads.  Although, there are some applications that may have a problem with the change in frequency that corresponds with the Power Save mode.

    Thus, if you do need to keep the device out of discontinuous operation, you may also try increasing the inductor value since the transition to Power Save mode occurs when the output load current drop below 1/2 the inductor ripple current.

    Sincerely,

    -Matt