I am designing an SMPS with MP2451 and there is a problem. These are my design rules.
Vin = 5V - 30V
Vout = 3V
Iout = 0.25A
MP2451 datasheet states that “Minimum switch time = 100ns”
So For 2Mhz constant switching frequency, period is 500nS and if we assume %100 efficiency maksimum Vin cannot higher than 3*5=15V.
Online design tool also approve that. It doesnt allow me to change Vin higher than 15V.
I assume MP2451 will use pulse skipping mode and switching frequency going down but it will work. It doesnt matter for me switching frequency lower but I am not sure it will work.
However there is V-I-efficiency graph in datasheet and it shows Vin=36V, Vout=5V.
Am I correct?
Can I design this SMPS with design rules which I stated it upside?