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參數資料
| 型號： | NCP1217P65G |
| 廠商： | ON SEMICONDUCTOR |
| 元件分類： | 穩壓器 |
| 英文描述： | Enhanced PWM Current−Mode Controller for High−Power Universal Off−Line Supplies |
| 中文描述： | 0.5 A SWITCHING CONTROLLER, 71.5 kHz SWITCHING FREQ-MAX, PDIP8 |
| 封裝： | LEAD FREE, PLASTIC, DIP-8 |
| 文件頁數： | 9/18頁 |
| 文件大小： | 249K |
| 代理商： | NCP1217P65G |
NCP1217, NCP1217A
http://onsemi.com
9
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.
Figure 16. The Current Source Brings V
CC
Above 12.8 V and then Turns Off
+
8
6
4
6 mA or 0
CV
CC
Aux
HV
12.8 V/5.6 V
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.
Figure 17. A Typical Startup Sequence for
the NCP1217
t, TIME (sec)
3.00 M
8.00 M
13.0 M
18.0 M
23.0 M
13.5
12.5
11.5
10.5
9.5
REGULATION
12.8 V
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 shortcircuit protection. A
shortcircuit actually forces the output voltage to be at 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, NCP1217
hosts a dedicated overload detection circuitry. Once
activated, this circuitry imposes to deliver pulses in a burst
manner with a low dutycycle. The system autorecovers
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
after a few switching cycles and selfsupplies 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 turnson 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.
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相關代理商/技術參數 |
參數描述 |
|---|---|
| NCP1218 | 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:PWM Controller with Adjustable Skip Level and External Latch Input |
| NCP1218AD65R2G | 功能描述:電流型 PWM 控制器 ANA PWM CONTROLLER RoHS:否 制造商:Texas Instruments 開關頻率:27 KHz 上升時間: 下降時間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數量:1 最大工作溫度:+ 105 C 安裝風格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
| NCP1219 | 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:PWM Controller with Adjustable Skip Level and External Latch Input |
| NCP1219AD100R2G | 功能描述:電流型 PWM 控制器 ANA PWM CONTROLLER RoHS:否 制造商:Texas Instruments 開關頻率:27 KHz 上升時間: 下降時間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數量:1 最大工作溫度:+ 105 C 安裝風格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
| NCP1219AD65R2G | 功能描述:電流型 PWM 控制器 ANA PWM CONTROLLER RoHS:否 制造商:Texas Instruments 開關頻率:27 KHz 上升時間: 下降時間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數量:1 最大工作溫度:+ 105 C 安裝風格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
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