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TPS62090-Q1: VBIAS input current

Henry Kang
Intellectual 1080 points
Part Number: TPS62090-Q1

Hi Team,

May i have your help to get the VBIAS input current at normal operation(5VIN/1.8VOUT/750kHz) condition?

  • 0
    TI__Expert 3465 points
    Hello Henry,

    what do you mean by VBIAS?
    This device does not have a pin named VBIAS, did you maybe mean IBIAS (since you mention input current)?
    If so, in our datasheet there is no so called parameter, so please elaborate a bit on the current you want to know and in which condition.
    If you simply need the total input current you need to calculate it with the formula:
    Iin=Vout*Iout/(efficiency*Vin)
    where the efficiency comes from the curve in the datasheet.
  • 0 in reply to Emmanuel Granatello
    TI__Intellectual 1080 points
    Hi Emmanuel,
    yes, what i want to know is IBIAS(device bias input current), the condition is 5VIN/1.8VOUT/750kHz.
  • 0 in reply to Henry Kang
    TI__Expert 5425 points

    Hi Henry,

    at no load you can use the quiescent current specified in the datasheet, in case you have load current I suggest the method Emmanuel explained already above.

    The TPS62090-Q1 can only be configured to 1.4MHz or 2.8MHz switching frequency. 750kHz is not an option. Please keep that in mind as well.

    For more details on how to understand quiescent current I suggest to read this application note.

  • 0 in reply to Juergen
    TI__Intellectual 1080 points
    Hi Juergen,
    Thanks for your information.
    The TPS62090-Q1 datasheet only shows quiescent current at non-switching, can we have the quiescent current at Vout=1.8V?
    Or can i use quiescent current at non-switching to replace the quiescent current at Vout=1.8V? i think they should be really similar.
  • 0 in reply to Henry Kang
    TI__Expert 5425 points
    Did you read the application note I mentioned above? I think it describes the analysis you plan to do in very detail. So I would expect that you find all answers to your questions there.
    Non switching is not related to the output voltage. It basically defines that there is no output current which means that there is no need to transfer power from the input to the output.
  • 0 in reply to Juergen
    TI__Intellectual 1080 points

    i did read the application note. and i totally understand the iq is not input current and it's defined at non switching condition.

    but the application note shows a datasheet which has quiescent current data at both non-switching/switching. so that's why i ask the iq again to see if we have iq  at switching condition or not. 

  • 0 in reply to Henry Kang
    TI__Expert 5425 points
    The second spec line for the quiescent current in the example shown above is including the current through the feedback divider on the output. From a device point of view this is a very low output current and requires switching at a very low frequency. You would find that information in the application note as well.
    Anyway, I assume you are trying to assess the losses in your circuit design. For that you can use WEBENCH as well. It can help you to calculate the losses in different parts of your DCDC converter application design in very detail.