HA16138PS Datasheet, PDF (15/20 Pages) Hitachi Semiconductor – AC/DC Switching Converter Controller IC With High-Voltage Power MOS FET

HA16138PS
Application Circuit Examples 1
The application circuit example shown here detects the secondary-side output voltage of a flyback power
supply. Secondary-side output voltage detection and feedback are performed by a shunt regulator and
photocoupler.
When the OVP latch function is used for secondary-side output voltage overvoltage protection, the FB pin
should be pulled up to VDD by the shunt regulator and photocoupler.
AC
INPUT
0.1µ
Line Filter
2200p
100µ
400V ₊
VR
260V
: Primary GND
: Secondary GND
Transformer
P: 90T / 1.43mH
S: 6T / 8.1µH
B: 14T / 30.8µH
OVP detection circuit (7.4V)
PS
51k
B
15µ
SBD
HRW26F
++
560µ 180µ
25V 25V
R3
330
R4
R6
1.8k 4.7k
C4
0.022µ
HA16138PS
R5
K 3.3k
A ^REF
HA17431VP
R7
2.4k
+
R8
330
R9
R11
1.8k 2.4k
C5
3.3µ DC
OUTPUT
5V/2A
R10
K 3.3k
A ^REF
HA17431VP
R12
2.4k
−
1 DRAIN SOURCE 8
OVP feedback circuit
2 DRAIN SGND 7
3 VDD
CT 6
4 FB
COMP 5
R1
120k
VR
15V
+ ^C1
47µ
20V
* The secondary-side output voltage is stabilized at a
value determined by the bleeder resistance of the
secondary-side shunt regulator.
VOUT(reg) = Vref(shunt) × ^{R11 + R12}
R12
=
2.5V
×
2.4kΩ + 2.4kΩ
2.4kΩ
= 5.0V
R2
15k
C2
2200p
C3
220p
Photo
coupler
Units R: Ω
C: F
When the OVP latch function is used, the secondary-side
voltage is detected by the shunt regulator, and feedback
to the FB pin is performed by the photocoupler. The OVP
detection level is determined by the following formula.
VOUT(ovp) = Vref(shunt) × ^{R6 + R7}
R7
=
2.5V ×
4.7kΩ + 2.4kΩ
2.4kΩ
= 7.4V
15