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LM53600N-Q1(Vout=3.3V, Spread Spectrum is Yes ) - About behavior at the temporary blackout of input voltage

Guru 21045 points

Hi Team,

 

Our customer would like to know about behavior at the temporary blackout of input voltage.

I understand that if the input voltage changes from 14V to 0V(temporary blackout), this device is disabled (HS & LS MOSFET is OFF).

At this time, does the regenerative energy (current) of the output capacitor flow into the input side?

I guess that if high side MOSFET have the body diode, this current flow into the input side.

And, could you please let us know if you have any concern?



 

Regards,

Kanemaru

  • Hello Kanemaru,

    Your description of current flow while input is less than output is accurate. Current will pass from the output capacitor through the high side FET’s body diode to the input even if the part is off.  As long as current levels remain reasonable, less than 2 A, the part should remain undamaged.  Freewheeling through the high side device’s body diode is also seen in FPWM mode while the part is subject to large load transients, also without damage.  The key to figuring out if this is OK is knowing the di/dt at the input node and the size of the output capacitor.  If you would like to share customer information so that I can check further in the lab, either email me directly at robert.blattner@ti.com or use the internal E2E. 

    Regards, Robert

  • Hi Robert-san,

     

    Thank you for the information and your kind support!

    Our customer have not been fixed the specifications yet.

    Therefore, I will contact you when I get new information.

     

    Regards,

    Kanemaru