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TPS61022: Is the input current related to the output current?

Wai Ian Lee
Prodigy 10 points
Part Number: TPS61022

Hi,

I'm wondering whether the output current for the TPS61022 will always be at 3A so long as the input voltage is anywhere between 2.7V - 4.35V as per the TPS61022's datasheet.

Does the input current not matter here or must it be more than 3A for the output current to be 3A?

Also, let's say my input voltage range is 0.7V - 5V. What would the output current in this case be?

Any form of guidance would be much appreciated.

Thank you in advance!

  • 0
    TI__Genius 12465 points

    Hi Lee,

    TPS61022 limits the inductor current (typ 8A, min 6.7A, which you can find in d/s), for Boost converter, the inductor current equals to input current. So it means the input current has a maximum limit for TPS61022.

    If you know the input voltage range, the output voltage, then you can know what the maximum output current is. For example, VIN=0.7V, Vout = 5V, the max output current is about 0.7*8/5 = 1.12A. This is a preliminary estimation because you don't consider the efficiency, the variation of input current limit...

    Or you can use the Webench design tool below to simulate the max current. Let me know if you have more questions

    webench.ti.com/.../ 

    Regards,

    Nathan

  • 0 in reply to Nathan Ding
    Prodigy 10 points

    Hi Nathan, 

    Thanks for your reply. 

    Please correct me if I'm wrong in my understanding. Assuming we go with the recommend specs from the application section in the d/s whereby we have an input voltage of 2.7-4.35V, does this mean that the single-cell Li-ion battery used here needs to have a minimum discharge current of at least 6.7A?

    Or does the TPS61022 regulate the current across the inductor which is usually 8A no matter what the discharge current of the battery/input is?

  • 0 in reply to Wai Ian Lee
    TI__Genius 12465 points

    Hi Lee,

    No. The 8A is current limit, it means when the inductor valley current is higher than 8A, TPS61022 will limit the current at 8A to protection the inductor and itself.

    The real inductor depends on your operation conditions, for example, if the battery voltage is 3.6V, output voltage is 5V, and the output current is 2A, the average inductor current is about 5V*2A/3.6V=2.7A, not 8A. But there is a very heavy load or the output is short to ground, the inductor current is possible higher than 8A, in these cases, TPS61022 will limit the inductor current.

    Regards,

    Nathan