Following is the MOSFET I am using in my power supply ( Topology - forward converter): PSMN1R8-40YLC Estimated power dissipated in the MOSFET (including the switch losses) is 4 W
My intention to calculate the temperature rise in the MOSFET due to the power dissipation in the MOSFET.
Basic understanding, Tj = Ta + RΘja * Pd -------------- Eqn (1)
Tj = Junction temperature
Ta = Ambient temperature (Taking as 25 °C)
RΘja = Junction to ambient thermal resistance
Pd = Power dissipated in the MOSFET
Following are the only thermal information available in the datasheet,
Information available is thermal resistance from junction to mounting base.
Q1) Can I calculate the junction temperature (using Eq(1)) using thermal resistance from junction to mounting base?
Q2) I understood that thermal resistance from junction to ambient is more related to PCB area and other factors, But still can we calculate the thermal resistance from junction ambient using thermal resistance from junction mounting base?