Dear TI Team
I have a question about the efficiency of the LMR33620.
When the input voltage is changed from 8V to 36V with the output voltage fixed as shown in the figure below, the efficiency is poor for all load currents. What is the reason?
I don't know the cause of the above phenomenon in the synchronous rectification type DCDC like LMR33620, so please let me know.
Best Regards,
Y.Ottey
Hi,
Do you mean that while other conditions are all the same, why does lower input voltage have higher efficiency?
If so,
1. Conduction loss: Higher Vin will lead to larger current ripple, which leads to higher mosfet conduction loss.
2. Switching loss: Higher Vin will lead to higher mosfet switching loss and diode reverse recovery loss
3. Besides, higher input will lead to higher copper loss(because of higher current ripple), input& output capacitor loss(because of higher current ripple), mosfet parasitic capacitance loss and IC loss.
Therefore, while other conditions are all the same, lower input voltage have higher efficiency.
Best regards,
Wendy
