LM5141-Q1: LM5141-Q1 EVM, how to select D1 and D2

Hi Eric,

D2 only conducts during the deadtime (the current commutation from the low-side FET's body diode to the antiparallel Schottky is highly dependent on inductive parasitics, so most of the current doesn't commutate if the deadtime is < 20ns). I think D1 is not required given the short deadtime of the LM5141-Q1, particularly if the low-side FET's body diode has a reasonable Qrr. Note also that D2 adds SW node parasitic capacitance, so it can reduce light-load efficiency when operating in CCM.

D1 is the boot diode that charges the boot cap - it should be rated for greater than the input voltage and typically more than 100mA. Usually, it's a Schottky diode to achieve low forward voltage drop, but also beware of possibly high reverse leakage current at high temperatures. A small SOD523 or SOD 323 package is adequate.

Regards,
Tim

Dear Tim:

    Thanks very much!

Regards!

Eric Shen