Can MP2451 use Vin higher than 15V when Vout=3V

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?


you can use the MP2451 above its minimum on time limit and it will skip cycles and lower the switching frequency. However I would use a lower frequency part like a MP4420 etc. for those high Vin/Vout voltage differentials, because AC switching losses increase by the square of the switched voltage and are proportional to the switching frequency. So the benefit of the lower possible inductor for high frequency operation is eaten up quick by more losses.

Thank you for your reply. I know there are lots of ac loses but it will be budget friendly solution and 0.25A is not much. I predict it will achive %75 efficiency and it is enough for me now. I want to use MP2451 because it is in basic part list in JLCPCB, also MP4420 cost much more. Thank you again.

Checked the JCB parts list. They have a MP2459 which is a 60V abs. max. 0.5A buck in TOT23-6 with 480kHz. It is pin for pin of the MP2451.


Thanks you for your help…