The following formulas show how to
estimate the device power dissipation under continuous conduction mode operations.
They must not be used if the device is working at light loads in the discontinuous
conduction mode.
Equation 16. Conduction loss: Pcon
= IOUT2 × RDS(on) ×
VOUT/VIN
Equation 17. Switching loss: Psw
= VIN × IOUT × 0.01
Equation 18. Quiescent current
loss: Pq = VIN × 0.01
Equation 19. Total loss: Ptot =
Pcon + Psw + Pq
Equation 20. Given TA ≥
Estimated junction temperature: TJ = TA + Rth
× Ptot
Equation 21. Given TJMAX =
125°C ≥ Estimated maximum ambient temperature: TAMAX =
TJMAX – Rth × Ptot