Hi,
If you look at the L298N datasheet.
It will tell you that a TOTAL of 4Amps.
BUT that comes with a fact that 2 amps per driver, and when conducting there is a typical 2V drop.
So 4W is being dissipated in HEAT in the chip, so it should have a heatsink on it.
The current that will be drawn through the IC will depend on the MOTORs you use, not the current rating of the power supply.
Tom... 