Consider the following synchronous buck converter:
where Q1 is the high-side and Q2 the low-side
When the high side Q1 device turns on, it will charge up the C_OSS of the low-side Q2 device. In the app note above, it states that this charge is usually ignored because eventually that charge on the C_OSS of Q2 will flow to the load and hence not be wasted.
However, and this is my question, when C_OSS of Q2 is being charged up in the first place (i.e. when Q1 high-side turns on), that is essentially a voltage source Vin charging a capacitor C_OSS of Q2 which is inherently a lossy operation (Is the 50% loss of energy when charging a cap from a battery a set rule in stone?) The discharging of Q2 C_OSS is loseless due to the inductor discharging it, however the charging up of Q2 C_OSS is not via the inductor, it is via the Vin and hence it should be lossy.
Why is the loss associated with the initial C_OSS charging of Q2 (low-side) when Q1 (high-side) turned on being ignored here?