GS65011-EVBEZ
EZDrive
TM
Open Loop Boost Evaluation Board
User’s Guide
_____________________________________________________________________________________________________________________
GSWPT-EVBEZ Rev190621
© 2019 GaN Systems Inc.
www.gansystems.com 8
Please refer to the Evaluation Board/Kit Important Notice on page 15
A Boost converter’s output voltage is higher than the input voltage, V
IN.
Under high duty
cycle and low load/no load operating conditions, the output voltage will rise and
potentially damage the GaN device. To avoid an overvoltage on the GaN device, two
actions are recommended. First, always apply a load at the output voltage, V
OUT
.
Secondly, pre-set the PWM signal before applying power to V
IN
.
Figure 4
shows the block
diagram of PWM signal generation inside the TL1454ACNSR.
PWM output
Duty Cycle Control
Freq control input
RT=120pF;
RT=R3+RT2=25k
Ω
;
Fsw=200kHz
Vpk=1.8V
Vvalley=1.2V
000 ohm)
Figure 4 •
GS65011-EVBEZ PWM signal adjustment diagram
The PWM signal is adjusted by tuning the controller’s peripheral resistors, R11 and R3. Use the
Table 1
to set the duty cycle with R11. Use
Table 2
to set the switching frequency with R3.
Select the appropriate values according to your own specifications and requirements. For a
safe start up, 10% duty cycle and frequency 250kHz is recommended.
Table 1
•
PWM Duty Cycle Setting up table
R11 (
Ω
)
IN1+ (V)
Duty Cycle
Case 1
1000
1.83
0 %
Case 2
850
1.74
10 %
Case 3
500
1.52
47 %
Case 4
0
1.15
100 %
Table 2
•
PWM Frequency Setting up table
f
SW_MIN
f
SW
f
SW_MAX
R3 (k
Ω
)
20
5
0
CT (pF)
120
120
120
f
SW
(kHz)
200
500
900
