an8029 Panasonic Corporation of North America, an8029 Datasheet - Page 5

• Manufacturer Part Number: an8029
• Description: Self-excited Rcc Pseudo-resonance Type Ac-dc Switching Power Supply Control Ic
• Manufacturer: Panasonic Corporation of North America

Voltage Regulators
[1] Operation descriptions
Pin No.
1. Start/stop circuit block
Terminal Equivalent Circuits (continued)
Application Notes
8
9
Start mechanism
ply voltage reaches the start voltage through
the current from start resistance, the IC starts
operation. Then the power MOSFET driving
starts. Thereby, bias is generated in the trans-
former and the supply voltage is given from
the bias coil to the IC. (point a in figure 1)
start voltage is reached and the voltage is gen-
erated in the bias coil to the time when the IC
is provided with a sufficient supply voltage,
the supply voltage of the IC is supplied by the
capacitor (C8) connected to V
When AC voltage is applied and the sup-
During the period from the time when the
V
CC
Equivalent circuit
Comp.
TON
5 A
7.3 V
V
CC
CC
9
8
.
TIM/OVP:
Terminal for use both OVP (overvoltage protec-
tion circuit) and timer latch.
[OVP]
When overvoltage signal of the power supply is
detected and high is inputted to the terminal, it
turns off the internal circuit. At the same time, it
holds that condition (latch). To reset the OVP latch,
the V
than the release voltage.
[Timer latch]
It detects the output voltage fall due to the
overcurrent condition of the power supply output
through the current level inputted to IFB. When
the I
value, the charge current flows in the capacitor
which is connected to this terminal. Then, when
the capacitor is charged up to the threshold volt-
age of the OVP, the OVP works so that the IC
could keep the operation stop condition.
FB:
Terminal for connecting the photocoupler for er-
ror voltage feedback of the power supply output.
It is possible to cancel about 180 mA of the dark
current of photocoupler.
Start
voltage
Stop
voltage
After AC rectification
IFB
CC
decreases under the current of certain
should be decreased to a voltage lower
GND
V
Before start
V
OUT
CC
Start resistance
Description
C8
Figure 1
R1
a
b
Start condition
Start
c
Start failure
Voltage supplied
from bias coil
AN8029
I/O
I
I
5