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| 型号： | NCP1378DR2 |
| 厂商： | ON Semiconductor |
| 文件页数： | 10/15页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR FLYBACK PWM 8-SOIC |
| 产品变化通告： | LTB Notification 03/Jan/2008 |
| 标准包装： | 2,500 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 100kHz |
| 电源电压： | 8.2 V ~ 18 V |
| 降压： | 无 |
| 升压： | 无 |
| 回扫： | 是 |
| 反相： | 无 |
| 倍增器： | 无 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 无 |
| 工作温度： | 0°C ~ 125°C |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 包装： | 带卷 (TR) |
| 其它名称： | NCP1378DR2OS |
NCP1378
An internal timer prevents any restart within 8.0 m s
further to the driver going-- low transition. This prevents the
switching frequency to exceed (1.0/T ON + 8.0 m s) but also
avoid false leakage inductance tripping at turn-- off. In some
cases, the leakage inductance kick is so energetic, that a
slight filtering is necessary.
inductance ringing has been fully damped. If this would not
be the case, the designer should install a small RC damper
across the transformer primary inductance connections.
Figure 23 shows where the sampling occurs on the
auxiliary winding.
The NCP1378 demagnetization detection pad features a
specific component arrangement as detailed by Figure 21.
In this picture, the zener diodes network protect the IC
against any potential ESD discharge that could appear on
the pins. The first ESD diode connected to the pad, exhibits
a parasitic capacitance. When this parasitic capacitance
(10 pF typically) is combined with Rdem, a restart delay is
created and the possibility to switch right in the
drain-- source wave exists. This guarantees QR operation
with all the associated benefits (low EMI, no turn-- on losses
etc.). Rdem should be calculated to limit the maximum
current flowing through pin 1 to less than
+3.0 mA/-- 2.0 mA: If during turn-- on, the auxiliary
8.0
6.0
4.0
2.0
0
4.5 m s
SAMPLING HERE
winding delivers 30 V (at the highest line level), then the
minimum Rdem value is defined by: 30 + 0.7/3.0 mA =
10.2 k Ω . This value will be further increased e.g. to
introduce a restart delay and also a slight filtering in case
of high leakage energy.
Figure 22 portrays a typical V DS shot at nominal output
power.
400
300
200
100
0
Figure 22. The NCP1378 Operates in
Borderline/Critical Operation
Overvoltage Protection
The overvoltage protection works by sampling the
plateau voltage 4.5 m s after the turn-- off sequence. This
delay guarantees a clean plateau, providing that the leakage
Figure 23. A Voltage Sample is Taken 4.5 m s
After the Turn--Off Sequence
When an OVP condition has been detected, the
NCP1378 enters a latchoff phase and stops all switching
operations. The controller stays fully latched in this
position and the startup source being still active, it keeps
the V CC going up and down between 8.4 V and 5.5 V. This
state lasts until the V CC is cycled down to 4.0 V, e.g. when
the user unplugs the power supply from the mains outlet.
By default, the OVP comparator is biased to a 5.2 V
reference level and pin1 is directly routed to the
comparator. As a result, when Vpin1 reaches 5.2 V, the
OVP comparator is triggered. The threshold can thus be
adjusted by either modifying the power winding to
auxiliary winding turn ratios to match this 5.2 V level or
insert a resistor from pin1 to ground to cope with your
design requirement.
Latching Off the NCP1378
In certain cases, it can be very convenient to externally
shut down permanently the NCP1378 via a dedicated
signal, e.g. coming from a temperature sensor (Figure 24).
The reset occurs when the user unplugs the power supply
from the mains outlet. To trigger the latchoff by an external
signal, a simple PNP transistor can do the work, as
Figure 25 shows.
http://onsemi.com
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相关代理商/技术参数 |
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| NCP1378DR2G | 功能描述:电流型 PWM 控制器 Quasi Resonant Current Mode PWM RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| NCP1378P | 功能描述:电流型 PWM 控制器 Quasi Resonant RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| NCP1378PG | 功能描述:电流型 PWM 控制器 Quasi Resonant Current Mode PWM RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| NCP1379 | 制造商:ONSEMI 制造商全称:ON Semiconductor 功能描述:Quasi-Resonant Current-Mode Controller for High-Power Universal Off-line Supplies |
| NCP1379_11 | 制造商:ONSEMI 制造商全称:ON Semiconductor 功能描述:Quasi-Resonant Current-Mode Controller for High-Power Universal Off-line Supplies |
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