The following formulas show how to estimate the device power dissipation under continuous conduction mode operations. These formulas must not be used if the device is working in the discontinuous conduction mode (DCM) or pulse-skipping Eco-mode.

The device power dissipation includes:

1. Conduction loss: Pcon = Iout² × R_DS(on) × V_OUT/VIN
2. Switching loss: Psw = 0.55 × 10^-9 × VIN² × I_OUT × Fsw
3. Gate charge loss: Pgc = 22.8 × 10^-9 × Fsw
4. Quiescent current loss: Pq = 0.082 × 10^-3 × VIN

Where:

• I_OUT is the output current (A).
• R_DS(on) is the on-resistance of the high-side MOSFET (Ω).
• V_OUT is the output voltage (V).
• VIN is the input voltage (V).
• Fsw is the switching frequency (Hz).

• Ptot = Pcon + Psw + Pgc + Pq
• For given T_A , T_J = T_A + Rth × Ptot.
• For given T_JMAX = 150°C, T_AMAX = T_JMAX– Rth × Ptot.

Where:

• Ptot is the total device power dissipation (W).
• T_A is the ambient temperature (°C).
• T_J is the junction temperature (°C) .
• Rth is the thermal resistance of the package (°C/W).
• T_JMAX is maximum junction temperature (°C).
• T_AMAX is maximum ambient temperature (°C).