AN8022L 查看數據表（PDF） - Panasonic Corporation
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AN8022L Datasheet PDF : 16 Pages
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Voltage Regulators
s Application Notes (continued)
[2] Operation descriptions (continued)
3. Overvoltage protection circuit (OVP) (continued)
TIM/OVP terminal voltage
VTH OVP
(to 6 V)
0V
AN8022L, AN8022SB
Time
Internal reference voltage
0V
(to 7.1 V)
(to 5 V)
(IC stop state)
Time
Triangular wave oscillation
0V
IC output
0V
(to 2 V)
(to VCC)
(IC stop state)
(IC stop state)
Figure 2. Explanation of OVP operation
Time
Time
After AC rectification
Start resistor
R1
VCC
Power supply output
Abnormal voltage applied from outside
FRD
OVP
VOUT
GND
Load
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.
Figure 3
• Operating supply current characteristics
While the OVP is operating, the decrease of the supply current causes the rise of the supply voltage VCC , and
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
VCC under OVP operation is stabilized over the OVP release supply voltage (which depends on start resistor
selection). (Refer to figure 4.)
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