I am designing a DC solid-state relay using an FQP30N06L (a MOSFET with 32 A, 60 V, Rds(on) = 0.035 Ω @Vgs = 10 V) to control using a Raspberry Pi.
I am trying to control an electric door lock with 6-12 V 1200 mA; the nominal resistance at 12 V is 9 Ω. I have seen many articles on the Internet, but all are confusing.
So, as per my specification:
The power dissipated by the MOSFET is P = I2 X R; I is the load current of electric door = 1.2 A; R is the Rds(on) of the MOSFET = 0.035 Ω.
This gives me a power dissipation of P = 1.2 A X 1.2 A X 0.035 Ω = 0.0504 W.