Application Note
7 of 23
V 1.1
2020-11-09
CoolGaN™ 600 V half-bridge evaluation platform featuring GaN
EiceDRIVER™
Circuit description
The transformer is based on a Ferroxcube EP10-3C96 ungapped core set. The matching EP10 single-section
bobbin is a part number CSHS-EP10-1S-8P-T. All 3 windings are made using 32 AWG magnet wire. The two
secondary windings are 9 turns each, and the primary is 10 turns, resulting in a magnetizing inductance of 87
µH. For full construction detail, contact your local Infineon applications support team.
3.3
Gate drive circuit
The output side of the gate driver circuit is shown in
. As explained in the GaN EiceDRIVER™ datasheet,
the gate driver contains two separate drive circuits, one (OUTG) connected to the CoolGaN™ gate, and the other
(OUTS) connected to the CoolGaN™ Kelvin source. VDDx is bypassed to VSSx with a 100 nF capacitor Cx3. The
gate RC network described in the datasheet consists of Rx4, Cx4 and Rx5. The small Schottky diode Dx5
provides a low-impedance return-path for faster gate turnoff, effectively bypassing Rx4.
Note that this circuit has an extra RC lowpass filter not shown in the datasheet, between OUTS and the Kelvin
source of the GaN. This circuit (Rx8 and Cx7) can help to provide a “cleaner” looking V
GS
gate drive voltage thus
the rise and fall time of the OUTS pin is very fast, and the added 3.3 ns time-constant provides some damping to
minimize high-frequency ringing. These components are optional, and can be effectively removed by
eliminating Cx7 and replacing Rx8 with a 0Ω jumper.
Similarly, Rx9 is an optional 1Ω damping resistor that can help to provide slightly overdamped voltage
waveforms at the gate. It can also be eliminated by replacing it with a 0Ω jumper if minimum component count
is desired. Rx7 is a standard 10 k gate pull-down resistor that helps ensure the gate-source voltage remains at
zero even when the gate driver is unpowered.
Figure 6
Gate driver output section