AN2842

Approach to the study

Doc ID 15110 Rev 1

11/22

2.2

Gate circuitry

Another reason for unbalanced current in a parallel topology is the gate circuitry. If a

common voltage source is used, the primary factor contributing to imbalance is mismatch

between decoupling resistors (if they are used). Normally, in order to reduce the impact of

the gate resistance, one can use different resistance for the drive gate circuit. In fact, if a

during the conduction operation. If we look at the previous paragraph, we can note that the

current imbalance is mainly present during the commutation and precisely during the

plateau zone. In order to reduce the current imbalance, it is necessary to decrease the

the commutation and oscillations.

2.3

Influence of the boost diode in the current imbalance

Among the key factors that influence current imbalances is the boost diode. In fact, the

performance of this component are determinant during the turn-on operation of devices in a

parallel configuration. The most important of the diode's characteristics for this topology is

current that was flowing to the boost diode has to flow through the device. The current value

is made up of three components; the first is the current coming from the inductor, the second

is the current coming from the recovery of the diode, while the last is the current from the

output capacitances of the devices.

Figure 13. Contribution of the current spike value during the turn-on phase

So, the contribution to the current spike value during the turn-on phase is due also to the

values are used, during turn-on operation a bigger difference in the current value of the peak

is present if an ultra fast diode and a fast diode are used. In

Figure 14 and Figure 15, details

during turn-on are shown.