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TPS62080A: About output short mode(abnormal condition)

Hide
Guru 21045 points
Part Number: TPS62080A

Hi Team,

 

Our customer would like to use TPS62080A at the following conditions.

Then, "VOUT1=3.3V" and "VOUT2=1.2V" may short-circuit.


 

I guess that each devices are not failed by this output short.

What I thought is as follows.

Is my understanding correct?

 

[My guess]

-At the first, the current flows from “TPS62080A_1” through the output capacitor of "TPS62080A_2" if each output voltage is shorted.

-After that, "VOUT1" and "VOUT2" become the same output voltage(1.2V).

-Then, the current limit of TPS62080A_1 works and TPS62080A_2 stops the switching(so low side FET is ON).

 

On the other hand, we worry whether “TPS62080A_2 side” does not fail because this device doesn't have the protection function for this phenomenon…

Could you please let us know if you have any concern and advice?

 

If you contact to below my e-mail address or let me know your e-mail address,

I can send the customer information.

I’m looking forward to hearing from you.

 

[my e-mail address]

Kanemaru-h@clv.macnica.co.jp

 

I’d greatly appreciate your verification.

 

Regards,

Kanemaru

  • 0
    TI__Guru*** 145580 points
    This is ok since the voltages are within the device's ratings and the device does not ever sink current. When a voltage is applied on the output (see point #6 in this app note on the product page: www.ti.com/.../slyt689.pdf), the IC will just enter PFM mode and stop switching.
  • 0 in reply to Chris Glaser
    Guru 21045 points

    Hi Chris-san,

     

    Thank you for the information.

    I confirmed the application note.


     

     

    And, I understood it as follows.

    Is my understanding correct?

     

    [My understanding]

    "VOUT1" and "VOUT2" become the same output voltage(3.3V) if each output voltage is shorted.

    Then, TPS62080A_1 is stable operation(so the current limit doesn't work) and TPS62080A_2 stops switching(so High and Low side MOSFET is OFF).


     

    Regards,

    Kanemaru

  • 0 in reply to Hide
    TI__Guru*** 145580 points
    Yes, TPS62080A_1 is operating normally. Its current limit still works.

    I don't know what you mean by reverse current. That node with the blue x is shorted to 3.3V. So, these are the same node in the circuit.
  • 0 in reply to Chris Glaser
    Guru 21045 points

    Hi Chris-san,

     

    Thank you for your response.

    And, I am sorry for confusing you.

    I understand that TPS62080A_2 stops the switching so the device does not sink current(Low side MOSFET is OFF).

    So, I wanted to show this understanding in a figure.

     

    Regards,

    Kanemaru

  • 0 in reply to Hide
    Guru 21045 points

    Hi Chris-san,

    Thank you very much for your help.

    Regards,

    Kanemaru