Electronic – Why 2 diodes in parallel buck converter design

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I have been looking up dc-dc buck converter designs and have question regarding the diodes.

  1. It says "5A High current Schottky diode" is it common in buck converter design to parallel diodes and I would guess this is two 2.5A diodes?

  2. I understand that connecting them in parallel will share the load and result in a higher forward current but wont one diode try to carry a larger current due a potential for a lower forward voltage. Resulting in one diode overheating?

  3. I know to remedy this is to add a series resistor with the diode to have a equal current drop across each resistor resulting in a almost equal current share between each diode. However this will result in a overall higher power loss due to the parallel branch and due to the large current drop in the resistor. Wouldn't you just be better paying a little more for a single diode that can meet the current requirement for your buck converter?

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I would apprecitae your feedback.

Thanks,

Best Answer

Paralleling the two diodes reduces the forward drop and increases the efficiency, as well as doubling the power dissipation. The I-V curves are soft enough that they will carry roughly equal current. Although the forward drop does go down on heating, you'd need to get almost to thermal runaway conditions before that would result in a large imbalance.

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