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| 型号： | NCP1377P |
| 厂商： | ON Semiconductor |
| 文件页数： | 11/17页 |
| 文件大小： | 0K |
| 描述： | IC CTRLR PWM CM OVP UVLO 8DIP |
| 产品变化通告： | LTB Notification 03/Jan/2008 |
| 标准包装： | 50 |
| 输出隔离： | 隔离 |
| 频率范围： | 100kHz |
| 输入电压： | 8.2 V ~ 18 V |
| 工作温度： | -40°C ~ 125°C |
| 封装/外壳： | 8-DIP（0.300"，7.62mm），7 引线 |
| 供应商设备封装： | 7-PDIP |
| 包装： | 管件 |
| 其它名称： | NCP1377POS |
NCP1377, NCP1377B
Thermistor
Rdem
1
2
3
4
8
7
6
5
Aux.
Winding
ON/OFF
1
2
3
4
NCP1377
8
7
6
5
Aux.
CV CC
Figure 25. A simple arrangement triggers
the latchoff as soon as the temperature
exceeds a given setpoint.
Shutting Off the NCP1377
Shutdown can easily be implemented through a simple
NPN bipolar transistor as depicted by Figure 27. When
OFF, Q1 is transparent to the operation. When forward
biased, the transistor pulls the FB pin to ground (Vcesat ≈
200 mV) and permanently disables the IC. A small time
constant on the transistor base will avoid false triggering
(Figure 27).
NCP1377
VCCcap
Figure 26. A simple transistor arrangement
triggers the latchoff as soon as the
temperature exceeds a given setpoint.
a low level, preventing a bias current to circulate in the
optocoupler LED. As a result, the auxiliary voltage also
decreases because it also operates in Flyback and thus
duplicates the output voltage, providing the leakage
inductance between windings is kept low. To account for
this situation and properly protect the power supply,
NCP1377 hosts a dedicated overload detection circuitry.
Once activated, this circuitry imposes to deliver pulses in
a burst manner with a low Duty Cycle. The system
auto ? recovers when the fault condition disappears.
ON/OFF
10 k
3
2
10 nF
Q1
1
1
2
3
4
8
7
6
5
During the startup phase, the peak current is pushed to
the maximum until the output voltage reaches its target and
the feedback loop takes over. The auxiliary voltage takes
place after a few switching cycles and self ? supplies the IC.
In presence of a short circuit on the output, the auxiliary
voltage will go down until it crosses the undervoltage
lockout level of typically 7.5 V. When this happens,
NCP1377 immediately stops the switching pulses and
unbiases all unnecessary logical blocks. The overall
Figure 27. A Simple Bipolar Transistor Totally
Disables the IC
Overload Operation
In applications where the output current is purposely not
controlled (e.g. wall adapters delivering raw DC level), it
is interesting to implement a true short ? circuit protection.
A short ? circuit actually forces the output voltage to be at
consumption drops, while keeping the gate grounded, and
the Vcc slowly falls down. As soon as Vcc reaches typically
5.6 V, the startup source turns ? on again and a new startup
sequence occurs, bringing Vcc toward 12.5 V as an attempt
to restart. If the default has gone, then the power supply
normally restarts. If not, a new protective burst is initiated,
shielding the SMPS from any runaway. Figure 28 portrays
the typical operating signals in short circuit.
http://onsemi.com
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相关代理商/技术参数 |
参数描述 |
|---|---|
| NCP1377PG | 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 |
| NCP1378 | 制造商:ONSEMI 制造商全称:ON Semiconductor 功能描述:PWM Current-Mode Controller for Free-Running Quasi-Resonant Operation |
| NCP1378/D | 制造商:未知厂家 制造商全称:未知厂家 功能描述:PWM Current-Mode Controller for Free Running Quasi-Resonant Operation |
| NCP1378_06 | 制造商:ONSEMI 制造商全称:ON Semiconductor 功能描述:PWM Current−Mode Controller for Free−Running Quasi−Resonant Operation |
| NCP1378DR2 | 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 |
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