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TPS55340: Output over voltage concern

Kazuki Itoh
Genius 9175 points
Part Number: TPS55340

Hello team,

My customer is trying to use TPS55340 for 12V-to-24V conversion with very small Io=73mA.

He concerns about the output overvoltage risk when the top resistor of the output resistor divider is open.

Do you think additional component such as Schottky diode at FP pin should be usually considered to support this type of overvoltage situation?

Also, I found that overshoot can be seen when input voltage SR is high and no output load  from this thread.

Is it better to tell my customer to take care about the input voltage in advance?

Regards,

Itoh 

  • 0
    TI__Guru 68765 points

    Hi Itoh-san,

    Thank you for posting.  You can add a Zener of the voltage equal to the max allowable Vout minus the TPS55340 FB reference voltage, which is 1.229V, and place the Zener in parallel with the high side feedback resistor, to catch the over-voltage event even if the high side resistor is open.  During normal operation, the Zener can be considered open.

    In the thread that you referred to, the application of your input voltage may cause resonant between the inductor and output capacitor, which may produce an over voltage even when the IC is not switching.  In this case, you need to slow down your input voltage application, or add an input inrush limit like a hot swap device, to prevent such resonance at input application.

    Thanks,

    Youhao Xi, Applications Engineering