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:

  1. 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.
  2. 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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