Mosfet in PWM Circuit

Can i use same mosfet number for Upper and Lower side MOSFET in PWM Circuit? Because I always see different mosfet number ( for example Laptop CPU V_Core used MDU1511RH mosfet and MDV1525URH mosfet ) and why?

by cygron
February 10, 2020

2 Answers

Answer by mrobbins

Both part numbers you mentioned are n-channel MOSFETs, but if you check out the datasheets, they do have different specs.

The MDU1511RH is a beefier, heavy-duty transistor: 2.4mΩ on-resistance, 100A max current.

The MDV1525URH is weaker: 10.1mΩ on-resistance, 13.8A max current.

So why would an engineer ever pick the MDV1525URH? Two good reasons I can see at first glance:

Lower gate charge (12.6nC versus 51.8nC for the 1511). Correspondingly, the 1525 has faster turn-on and turn-off times, which is important for high switching frequencies. Higher switching frequencies lower the size and cost of capacitors and inductors in your switching power supply.
Lower unit price (about 5 cents, versus 35 cents for the 1511). Adds up when you're making things at scale!

+3 votes
by mrobbins
February 17, 2020

Answer by cygron

Thanks for your explain.

+1 vote
by cygron
March 02, 2020

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