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TPS55340: Separate “VIN” and " regulation voltage(VREG)"

Guru 21045 points
Part Number: TPS55340
Other Parts Discussed in Thread: TPS61200

Hi Team,

 

Our customer would like to use the following conditions(separate “VIN” and " regulation voltage(VREG)").

Because, minimum VREG is 0.5V so this voltage is lower than the recommended operating conditions of VIN.

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

 

[Conditions]

-VIN=3.0V

-VREG=0.5V to 6.2V

-IOUT=TBD

-VOUT=around 6.5V


 

Regards,

Kanemaru

  • Hello Kanemaru,

    Is there a way of supply Vin with a voltage that is higher than 3V? This is so close to the minimum voltage there could be issues in the TPS55340 operation is there is any fluctuation.

    That said I have worked on designs with parts like this where the VIN is sourced from another supply or where VIN is diode OR'd with Vreg and Vout. This should work in most cases but it would be better if VIN could be raised to a higher voltage or if it could possibly be diode OR'd with Vout to give the TPS55340 a much higher internal voltage (This will also boost your efficiency since the internal FET will have much lower Rdson). This is one area of operation that will have some issues even with VIN sourced separately from VREG.

    What will be a bigger issue is the Duty Cycle limit of the TPS55340 which is 90%. This means you will lose 6.5V regulation any time your Vreg is below 700-800mV.


    On a different note. How likely is 6.2V on the input and how critical is 6.5V on the output? The reason I ask is if these peak values could are unlikely or if the input could be clamped it would be interesting to have you look at the TPS61200 since it supports input voltages all the way down to 300mV. This is also dependent on the current requirements that you have in this application.
  • Hi Ryan-san,

     

    Thank you for the information and advice.

    I will suggest TPS61200.

     

    Regards,

    Kanemaru