Avago Technologies ACPL-224-500E - Manual (Page 65)

AV02-4387EN 62 Avago Technologies
Description
The above figure shows a push-pull
switching power supply that uti-
lizes the HCPL-2200 optocoupler
to drive switching transistors. The
above circuit uses a silicon unilateral
switch (SUS) to bootstrap start the
power supply when power is first
applied. The inhibit function in the
HCPL-2200 optocoupler has been
used to good advantage to provide
a common-mode conduc tion inter-
lock function that will not allow both
the switching transistors to turn on
at the same time.
Performance of Optocoupler
• Maximum propagation delay: 300
ns
• Input turn­on current: 1.6 mA
• Common­mode transient rejec-
tion: 1000 V/µs
Benefits
• The power switches are protected
from common-mode conduction
failures caused by EMI
• Regulation range is increased
since no deadtime is required
• Design is tolerant to propaga tion
delay changes due to lot-to-lot
component variations
References
HCPL-2200 High CMR Optocoupler
Technical Data
Alternative Avago Parts
1) HCPL-2219 Very High CMR Opto-
coupler
2) HCNW2601/11 Widebody High
CMR Optocoupler
AC
POWER
PWM CHIP
L
N
5 V
+
HCPL-2200
5 V
+
HCPL-2200
+
ISOLATED
DC
OUTPUT
SUS*
CATHODE
ANODE
* SUS = SILICON UNILATERAL SWITCH
D1 R3
C1 R4
R1
C2
R2
R7
R9
D2
C3
C4
D3
R5
R6
R8
R11
R12
R10
C8
C6 C7
L1
D5
D4
R13
Optical Isolation in a Switching Power Supply - Circuit No. 2
Power Supply Applications