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TPS63060 / Swhiching behavior

Ryuji
Guru 20090 points
Other Parts Discussed in Thread: TPS63060
Hello,
 
I have the quesiton about switching behavior of TPS63060 L1, L2 pins.
Please see the attached file as my waveform of TPS63060 L1, L2 pins.
 
 
Page1 :Vin=4.1V, Vout=4.5V, Iout=300mA, L=1.0uH, PSmode
       This is Boost mode. Thus L1 pin is permanently High.
 
Page2 :Vin=5.3V, Vout=4.5V, Iout=300mA, L=1.0uH, PSmode
       This is Buch mode. But L2 pin has Low period.
       I think that L2 pin should be permanently high for the Buck mode.
       Could you please let me know this operation reason ?
 
Best Regards,
Ryuji Asaka
  • 0
    TI__Expert 7110 points

    Ryuji-san,

    the TPS63060 features a seamless transition between the modes and provides an accurate output voltage even when  VIN is close to VOUT. Therefore in this region both stages switches.

    How did you measure your voltages? Checking the waveforms you sent, it looks for me as if the input voltage is more like 4.6V to 4.7V and the output voltage approx. 4.2V?


    Regards,

    Florian

  • 0 in reply to Florian Feckl
    Guru 20090 points
    Hello Florian san,
     
    Thank you for the reply.
    Input Voltage is setting value of DC Power Supply.
    Concerning output, voltage is about 4.37V (R1=774kohms, R2=100kohms).
     
    I understood that we need voltage difference and Iout for Buck  or Boost  swiching only operation.
    In my measurement by TPS63060EVM (Vout=5V setting) , these values are following.
    Buck Mode : difference voltage is about 0.6V, Iout =300mA
    Boost Mode : difference voltage is about 1V , Iout=200mA
     
    Best Regards,
    Ryuji Asaka
     
  • 0 in reply to Ryuji
    TI__Expert 7110 points

    Ryuji-san,

    Exactly, your understanding is right. There is a certain voltage window around the VIN / VOUT transition point.

    But it is just a few 100mV. To get fair numbers, please make sure to measure the voltages applied to the device. This means, there will be drop from your power supply to the device. You can figure out the voltages e.g  by the scope curves you took.

    Regards,
    Florian

  • 0 in reply to Florian Feckl
    Guru 20090 points
    Hello Florian san,
     
    Thank you for the reply.
    I understood that certain voltage window is around 100mV.
    I will check again by EVM.
     
    Best Regards,
    Ryuji Asaka