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參數(shù)資料
| 型號： | AN8021NS |
| 廠商： | PANASONIC CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | External excitation flyback AC-DC switching power supply control IC |
| 中文描述： | 1 A SWITCHING CONTROLLER, 700 kHz SWITCHING FREQ-MAX, PDSO8 |
| 封裝： | 0.225 INCH, PLASTIC, SOP-8 |
| 文件頁數(shù)： | 9/16頁 |
| 文件大?。?/td> | 141K |
| 代理商： | AN8021NS |
9
Voltage Regulators
AN8021L, AN8021SB
I
Application Notes (continued)
[2] Operation descriptions (continued)
3. Overvoltage protection circuit (OVP)
OVP is an abbreviation of Over Voltage Protection. It refers to a self-diagnosis function, which stops the power
supply to protect the load when the power supply output generates abnormal voltage higher than the normal
output voltage due to failure of the control system or an abnormal voltage applied from the outside (figure 2 and
figure 3).
Basically, it is set to monitor the voltage of supply voltage V
CC
terminal of the IC. Normally, the V
CC
voltage
is supplied from the transformer drive coil. Since this voltage is proportional to the secondary side output voltage,
it still operates even when the secondary side output has overvoltage.
1) When the voltage input to the OVP terminal exceeds the threshold voltage (6.0 V typical) as the result of power
supply output abnormality, the protective circuit shuts down the internal reference voltage of the IC to stop all
of the controls and keeps this stop condition.
2) The OVP is released (reset) under the following conditions:
Decreasing the supply voltage (V
CC
<
8.4 V typical: OVP release supply voltage)
The discharge circuit is incorporated so that the electric charge which is charged in the capacitor
connected to the OVP terminal can be discharged with the constant current of 5
μ
A (typical) for the next re-start.
Secondary side output voltage under normal operation V
OUT
×
V
7
V
CC
terminal voltage under normal operation
V
7
=
V
th(OVP)
+
V
Z
V
th(OUT)
: Secondary side output overvoltage threshold
V
th(OVP)
: OVP operation threshold
V
Z
: Zener voltage (external parts of OVP terminal)
V
th(OUT)
=
(to V
CC
)
0 V
IC output
(to 5 V)
0 V
Triangular wave oscillation
(to 7.1 V)
(IC stop state)
(IC stop state)
(IC stop state)
0 V
Internal reference voltage
(to 6 V)
0 V
TIM/OVP terminal voltage
Time
Time
Time
Time
(to 2 V)
V
TH
OVP
Figure
2. Explanation of OVP operation
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| AN8021L | AC-DC switching power supply control IC |
| AN8022L | AC-DC switching power supply control IC |
| AN8022SB | AC-DC switching power supply control IC |
| AN8026 | Self-excited RCC pseudo-resonance type AC-DC switching power supply control IC |
| AN8027 | AC-DC switching power supply control IC with standby mode |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| AN8021SB | 制造商:PANASONIC 制造商全稱:Panasonic Semiconductor 功能描述:AC-DC switching power supply control IC |
| AN8022 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述: |
| AN8022L | 制造商:PANASONIC 制造商全稱:Panasonic Semiconductor 功能描述:AC-DC switching power supply control IC |
| AN8022SB | 制造商:PANASONIC 制造商全稱:Panasonic Semiconductor 功能描述:AC-DC switching power supply control IC |
| AN-8023 | 制造商:FAIRCHILD 制造商全稱:Fairchild Semiconductor 功能描述:Negative Voltage Management |
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