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TPS62261-Q1: DC-DC converter, TPS62261-Q1

sundararao yanamala
Intellectual 260 points
Part Number: TPS62261-Q1
Other Parts Discussed in Thread: TPS62261, TPS62293-Q1,

Hello TI,

Justify decision on whether the TPS62251 is capable of supporting the circuit requirements, if the worse case calculated peak current is 700mA.

Our understating:

The 600mA is an average output current of the TPS62261 power supply circuit, but it is not the actual limitation.  The average output current of a SWPS is depended upon the selection of the discrete components (particularly the buck inductor) that make up the power supply in addition to the controller selection.  The actual limitation of the power supply controller is the peak current limit of the component(internal FETs), which for the TPS62261 is 1.0A typical (0.8A to 1.2A min/max) cycle-by-cycle current limit of the current mode switching power supply as per its datasheet.  

  • 0
    TI__Guru*** 142750 points
    Yes, this is correct, but why not use the pin to pin, 1A TPS62293-Q1?
  • 0 in reply to Chris Glaser
    Intellectual 260 points

    Hello Chris, Thanks for your reply,

    Due to digital circuit change, the previous worse case load current 600mA has been raised to 700mA. So thinking that this current change will not impact on power supply (TPS62261-Q1). That's only the reason behind it. we will think of use TPS62293-Q1.

    Thanks,

    Sundar Y

  • 0 in reply to sundararao yanamala
    Intellectual 260 points
    Hello Chris,

    One correction in previous question. So, requesting answer for below New Question on TPS62261-Q1.

    Previous Question: Justify decision on whether the TPS62251 is capable of supporting the circuit requirements, if the worse case calculated PEAK current is 700mA?

    New Question: Justify decision on whether the TPS62251 is capable of supporting the circuit requirements, if the worse case calculated MAXIMUM current is 700mA?
  • 0 in reply to sundararao yanamala
    Intellectual 260 points

    Hello Chris,

    One correction in previous question. So, requesting answer for below New Question on TPS62261-Q1.

    Previous Question: Justify decision on whether the TPS62261 is capable of supporting the circuit requirements, if the worse case calculated PEAK current is 700mA?

    New Question: Justify decision on whether the TPS62261 is capable of supporting the circuit requirements, if the worse case calculated MAXIMUM current is 700mA?

  • 0 in reply to sundararao yanamala
    TI__Guru*** 142750 points
    If you click on 'more', you can edit your post rather than post a new post.

    I don't understand your question. The devices are pin to pin, so it is safest to just use an IC which is rated to supply the current that you need.

    Assuming you have 5Vin, the peak inductor current exceeds the 0.8A spec I believe (from equation 1 and 2). So, drawing 700 mA would not be operating within the spec and might be limited by the current limit.
  • 0 in reply to Chris Glaser
    Intellectual 260 points

    Hello Chris,

    Thanks for advise and sorry for repeating question again,

    For your information,  Vin = 3V3, output voltage = 1V8, maximum load current requirement = 700mA, Calculated peak inductor current = 823mA.

    Considering above conditions, is TPS62261 device capable to support maximum load current of 700mA?

    Please provide your final answer.

     Thanks

  • 0 in reply to sundararao yanamala
    TI__Guru*** 142750 points
    Since your peak current calculated is above the minimum level of the current limit, that output current cannot be reliably supported. If the current limit occurs at the lower level, the IC will enter current limit operation and prevent the inductor current from increasing further, before your load reaches 700 mA.