Gan Systems GS66504B-EVBDB GaN E-HEMT, Руководство пользователя

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GS66504B-EVBDB 650V
GaN E-HEMT Evaluation Board
User’s Guide
_____________________________________________________________________________________________________________________
GS66504B-EVBDB UG rev. 161120 © 2016 GaN Systems Inc. www.gansystems.com 5
Please refer to the Evaluation Board/Kit Important Notice on page 29
Gate drive power supply:

Bipolar gate drive bias with +6V and -3V for turning off is chosen for this design for more robust
gate drive and better noise immunity.

5V-9V isolated DC/DC converters are used for gate drive. 9V is then splited into +6V and -3V bias
by using 6V Zener diode

By default gate drive supply input VDRV is tied to VCC +5V via 0Ω jumper (FB1). Remove FB1 if
separate gate drive input voltage is to be used.
Gate driver circuit:

Silab Si8271GB-IS (6V gate drive) or Si8271AB-IS (6/-3 gate bias) isolated gate driver can be used
for this design. This driver is compatible with 6V gate drive with 4V UVLO and has CMTI dv/dt
rating up to 200V/ns. It has separated source and sink drive outputs which eliminates the need
for additional diode.

GaN E-HEMT switching speed and slew rate can be directly controlled by the gate resistor. By
default the turn-on Rgate (R6/R12) is 15Ω and turn-off gate resistor (R7/R14) is 2Ω. User can
adjust the values of gate resistors to fine tune the turn-on and off speed.

FB1/FB2 are 0603 footprints for optional ferrite beads for damping gate ringing/oscillation. By
default they are populated with 0Ω jumpers. If gate oscillation is observed, it is recommended to
replace them with ferrite bead with Z=10-20
Ω
@100MHz.
Figure 5 Gate driver circuit
RC Snubber:
RS1/CS1 and RS2/CS2 are place holders to allow user to experiement with RC snubber circuit (not
installed). At high frequency operation the power dissipation for RS1/RS2 needs to be closely watched
and CS1/CS2 should be sized correctly. It is recommended to start with 33-47pF and 10-20
Ω
.
PS2
PES1-S5-S9-M
GND
1
VIN
2
+VO
5
0V
4
NC
8
0V
VDRV
C14
4.7uF
C0805 C16
4.7uF
C0805
R9
3.3K
LED2
LED-0603
VDDL_+9V
U4
SI8271GB-IS
VI
1
VDDI
2
GNDI
3
EN
4
GNDA
5
VO-
6
VO+
7
VDD
8
PWML
JP1
CON-JMP-CSHUNT
VDDL_+6V
GNDL
C15
4.7uF
C0805
DZ2
6.2V
SOD323-AC
A
C
R16
1K C21
4.7uF
C0805
VEEL
VEEL
GNDL
C22
1uF
GNDL
FB1
0R
VDRV VCC_+5V
R10
3.3K
R11
10R
PWML_IN
PGND
Q2S
Q2
GS66504B
1
2
3
ENABLE
R13
3.3K
Q2G
FB3
0R
R12
15R
R14
2R
Q2_GOUT Q2_VO+
GNDL
Q2_VO-
C17
1uF
RS2
33R
R1206
CS2
100p 1kV
C1206
VDDL_+6V
DNP
C18
1uF
DNP
0V
VCC_+5V