From the LM5030 data sheet "output section", tr=tf=16ns, Cload=1nF, VCC=10V and your calculation of 625 mA is correct. the data sheet states 1.5A peak current but often times the peak value of the current is not aligned with the Miller Plateau. The real current we care most about is the available current at the Miller Plateau which drives the transition from LOW/HIGH and vice versa. The value of peak current depends upon many factors such as PCB layout, circuit parasitics, source/sink impedance and measurement technique. the actual waveform would be helpful here but this is not included as part of our automated test coverage.
Here is an example of the peak source/sink current for a gate driver rated at 4A. The cursor is placed near the estimated equivalent "Miller Plateau" and you can see the value of the peak current happens before the4 output voltage has a chance to rise/fall to within 10%/90% of the steady state value. When the load is a Si MOSFET which has non-linear capacitance, the effect can be so bad that the peak current value appears during the MOSFET delay time which is well before the switching transition. This is why peak current ratings should be considered with caution.
Regards,
Steve M
