an8022l Panasonic Corporation of North America, an8022l Datasheet - Page 9

• Manufacturer Part Number: an8022l
• Description: Ac-dc Switching Power Supply Control Ic
• Manufacturer: Panasonic Corporation of North America

Voltage Regulators
[2] Operation descriptions (continued)
After AC rectification
3. Overvoltage protection circuit (OVP) (continued)
Application Notes (continued)
Triangular wave oscillation
TIM/OVP terminal voltage
GND
Internal reference voltage
in the worst case, the guaranteed breakdown voltage of the IC (35 V) can be exceeded. In order to prevent the rise
of supply voltage, the IC is provided with such characteristics as the supply current rises in the constant resistance
mode. This characteristics ensure that the OVP can not be released unless the AC input is cut, if the supply voltage
V
selection). (Refer to figure 4.)
V
Operating supply current characteristics
CC
OVP
V
OUT
While the OVP is operating, the decrease of the supply current causes the rise of the supply voltage V
CC
under OVP operation is stabilized over the OVP release supply voltage (which depends on start resistor
Start resistor
IC output
R1
0 V
0 V
0 V
0 V
Figure 2. Explanation of OVP operation
(to 7.1 V)
(to V
(to 5 V)
(to 2 V)
CC
)
Figure 3
It detects abnormal voltage applied from the outside to the
power supply output (the voltage which is higher than voltage
of the power supply output and may damage the load) by the
primary side of the bias coil and operates the OVP.
FRD
V
(to 6 V)
TH
OVP
Power supply output
Load
(IC stop
(IC stop
(IC stop
Abnormal voltage applied from outside
state)
state)
state)
AN8022L, AN8022SB
CC
Time
Time
Time
Time
, and
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