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| 型号： | NCP1217AD100R2 |
| 厂商： | ON Semiconductor |
| 文件页数： | 9/19页 |
| 文件大小： | 0K |
| 描述： | IC CTRLR PWM CM OVP HV 8SOIC |
| 产品变化通告： | LTB Notification 03/Jan/2008 |
| 标准包装： | 2,500 |
| 输出隔离： | 隔离 |
| 频率范围： | 90kHz ~ 110kHz |
| 输入电压： | 8.3 V ~ 16 V |
| 工作温度： | 0°C ~ 125°C |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 供应商设备封装： | 8-SOICN |
| 包装： | 带卷 (TR) |
NCP1217, NCP1217A
Startup Sequence
When the power supply is first powered from the mains
outlet, the internal current source (typically 7.0 mA) is
biased and charges up the V CC capacitor. When the voltage
on this V CC capacitor reaches the VCC ON level (typically
12.8 V), the current source turns off and no longer wastes
any power. At this time, the V CC capacitor only supplies the
controller and the auxiliary supply is supposed to take over
before V CC collapses below VCC min . Figure 16 shows the
internal arrangement of this structure.
8
HV
12.8 V/5.6 V
+
--
6 mA or 0
6
CV CC
Aux
4
Figure 16. The Current Source Brings V CC Above 12.8 V and then Turns Off
Once the power supply has started, the V CC shall be
constrained below 16 V, which is the maximum rating on
Pin 6. Figure 17 portrays a typical startup sequence with a
V CC regulated at 12.5 V.
13.5
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, NCP1217
hosts a dedicated overload detection circuitry. Once
12.5
11.5
12.8 V
REGULATION
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.
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
10.5
9.5
3.00 M 8.00 M 13.0 M 18.0 M 23.0 M
t, TIME (sec)
Figure 17. A Typical Startup Sequence for
the NCP1217
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 a low
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 7.6 V. When this happens,
NCP1217 immediately stops the switching pulses and
unbiases all unnecessary logical blocks. The overall
consumption drops, while keeping the gate grounded, and
the V CC slowly falls down. As soon as V CC reaches typically
5.6 V, the startup source turns--on again and a new startup
sequence occurs, bringing V CC toward 12.8 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 18 portrays
the typical operating signals in short circuit.
http://onsemi.com
9
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相关代理商/技术参数 |
参数描述 |
|---|---|
| NCP1217AD100R2G | 功能描述:电流型 PWM 控制器 Current Mode PWM w/50% Duty Cycle Max 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 |
| NCP1217AD133R2 | 功能描述:电流型 PWM 控制器 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 |
| NCP1217AD133R2G | 功能描述:电流型 PWM 控制器 Current Mode PWM w/50% Duty Cycle Max 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 |
| NCP1217AD65R2 | 功能描述:电流型 PWM 控制器 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 |
| NCP1217AD65R2G | 功能描述:电流型 PWM 控制器 Current Mode PWM w/50% Duty Cycle Max 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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