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LM25118 using parallel diodes for recovery and output diodes...

Eclipze
Intellectual 641 points
Other Parts Discussed in Thread: LM5118, LM25118

I am interested to understand the reason for the webench simulations, evaluation kit and datasheet example all using parallel Schottky diodes for the recovery and output diode.

My design requirements are Vin 6 to 36V, Vout 12V@2A.  Although even at 0.25A, the webench generated circuit still has two sets of parallel diodes.

  • 0
    TI__Genius 16025 points

    Hi Eclipze,

    It looks like you've been looking at schematics of LM5118 or LM25118. We agree this is interesting behavior for the simulator. We will mention it to the local WeBench team. It looks like that this particular simulator uses a generic template for the diode selection. Most implementations of this device are for higher currents, where parallel diodes are usually necessary. For lower current cases, the application can reduce diode count by making sure that the single diode can easily handle the sum of the two individual diode currents. Be aware that the single inductor non inverting buck boost topology (aka Single inductor four switch flyback) has considerable switch and inductor currents which don't seem obvious given even moderate load currents. The reason is that the energy storage in the inductor is substantial.

    Thanks,

    Anston

  • 0 in reply to Anston Lobo
    Intellectual 641 points

    Thankyou Anston.  Your answer supports my understanding.