tlv8312 power losses

The TLV8312 data sheet shows typical efficiency (vs PWM frequency) at 5A output current.  However this doesn't tell me the absolute power loss, and therefore the expected temperature rise without knowing how much poweris delivered to the load: is it 5A at 1V, or 5A at 50V?

I can calculate the resistive losses but not the switching losses. 

Using 5A and 160mohm on resistance, for a simplistic assumption with one high FET and one low FET conducting, both 80mohms, gives P(loss) = 5^2 x 0.08 x 2 = 4W resistive losses

Can anyone tell me the switching losses / or the total power dissipated in the device, corresponding to the efficiency plot  .