HA16138PS Hitachi Semiconductor (acquired by Renesas), HA16138PS Datasheet - Page 16

• Manufacturer Part Number: HA16138PS
• Description: Ac/dc Switching Converter Controller ic With High-voltage Power MOSFET
• Manufacturer: Hitachi Semiconductor (acquired by Renesas)

HA16138PS
Application Circuit Examples 2
The application circuit example shown here detects the primary-side back-up output voltage of a flyback
power supply. As the back-up output voltage, VDD is resistance-divided and feedback is performed to the
FB pin. The back-up output voltage and secondary-side output voltage are proportional to the ratio of
transformer windings. Using this characteristic enables the system to be configured with simple circuitry
as shown in the figure below.
The VDD-to-FB feedback resistance can also be used as the back-up output voltage OVP detection
resistance.
16
* If feedback resistance R1 = 240 k
AC
INPUT
feedback is performed so that the FB pin voltage is
non-inverting input voltage V
is stabilized.
VDD(reg) = V
0.1
: Primary GND
: Secondary GND
Line Filter
= 3.8V
= 11.4V
(+)EA
240k + 120k
R1 + R2
400V
100
R1
240k
R2
120k
R2
120k
2200p
+
(+)EA
VR
15V
VR
260V
, and the VDD voltage
+
C1
47
20V
and R2 = 120 k ,
51k
Transformer
P: 90T / 1.43mH
S: 6T / 8.1 H
B: 14T / 30.8 H
1
2
3
4
P
B
DRAIN
DRAIN
VDD
FB
HA16138PS
S
SOURCE
SBD
HRW26F
C2 0.1
COMP
SGND
R3 1M
CT
When the FB pin voltage reaches OVP latch set
voltage Vovp, the OVP latch circuit operates, shutting
down the IC. The VDD voltage in this case is given
by the following formula.
VDD(ovp) = Vovp
560
25V
8
7
6
5
+
15
= 5.0V
= 15V
180
R4
15k
25V
+
C3
2200p
240k + 120k
R1 + R2
Units R:
DC
OUTPUT
5V/1A
R2
120k
C4
220p
C: F
+