**Part Number:**UCC5350-Q1

Hi Team,

My customer Preh has a question about the UCC5350-Q1:

How to calculate the RMS current for gate drivers.

4x Gate Driver UCC5530 for H-bridge control are in use and a Gate Driver will each drive an IGBT, which each IGBT 650nC gate charge has.

The switching frequency with approx. 50% duty cycle is f_sw=60kHz.

The 15V_supply supplies VCC2 at the gate driver. A transformer inductance must be dimensioned at the input of the 15V_supply and for this I need the RMS current.

1) is the RMS current calculated like this?

t_on=1/(f_sw/2)=8,3µs

I_RMS_per_driver= Q/t_on =650nC*8,3µs=78mA

I_RMS_total:= I_RMS_per_driver*2 = 156mA (2x gate drivers activated simultaneously)

2) or so?

Charge is converted as a capacitor.

C=Q/V=650nC/15V=43,3nF

Calculate Tau:

=1.365ohm+3.75ohm+2.5ohm=7.6ohm

Tau_on_nom=Ron_total_nom*C=310,2ns

The current curve during capacitor charging:

Peak current I_OH_nom is calculated as in the data sheet=15V/7.6ohm=1.97Ampere

Then the RMS current is calculated for the t_on duration:

I_RMS_total=IG_on_nom_RMS*2 = 537mA (2x gate drivers activated simultaneously)

Thanks and best regards

David