參數(shù)資料
型號(hào)： NCP1217AP65G
廠商： ON SEMICONDUCTOR
元件分類： 穩(wěn)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(yè)數(shù)： 13/18頁(yè)
文件大?。?/td> 249K
代理商： NCP1217AP65G
NCP1217, NCP1217A
http://onsemi.com
13
In normal operation, the Adj pin level is kept at a fixed
level, the default one or lower. As soon as some external
signal pulls this Adj pin level above 3.1 V typical, the output
pulses are permanently disabled. Care must be taken to limit
the injected current into pin 1 to less than 2.0 mA, e.g.
through a series resistor of 5.6 k with a 10 V V
CC
. The
startup switch is activated every time V
CC
reaches 5.6 V and
maintains a V
CC
voltage ramping up and down between
5.6 V and 12.8 V. Reset occurs when V
CC
falls below 5.6 V,
e.g. when the user cycle the SMPS down. Figure 25
illustrates the operation. Adding a zener diode from Q1 base
to ground makes a cheap OVP, protecting the supply from
any lethal openloop operation. If a thermistor (NTC) is
added in parallel with the Zenerdiode, overtemperature
protection is also ensured.
Figure 25. A Thermistor and a Zener Diode Offer
Both OVP and Overtemperature LatchedOff
Protection
Laux
8
7
6
5
1
2
3
4
Vaux
CV
CC
16 V
OVP
T
Nonlatching Shutdown
In some cases, it might be desirable to shut off the part
temporarily and authorize its restart once the default has
disappeared. This option can easily be accomplished
through a single NPN bipolar transistor wired between FB
and ground. By pulling FB below the Adj Pin 1 level, the
output pulses are disabled as long as FB is pulled below
Pin 1. As soon as FB is relaxed, the IC resumes its operation.
Figure 26
depicts the application example.
Figure 26. Another Way of Shutting Down the IC
Without a Definitive Latchoff State
8
7
6
5
1
2
3
4
Q1
ON/OFF
Protecting the Controller Against Negative Spikes
As with any controller built upon a CMOS technology, it
is the designer’s duty to avoid the presence of negative
spikes on sensitive pins. Negative signals have the bad habit
to forward bias the controller substrate and induce erratic
behaviors. Sometimes, the injection can be so strong that
internal parasitic SCRs are triggered, engendering
irremediable damages to the IC if a low impedance path is
offered between V
CC
and GND. If the current sense pin is
often the seat of such spurious signals, the highvoltage pin
can also be the source of problems in certain circumstances.
During the turnoff sequence, e.g. when the user unplugs the
power supply, the controller is still fed by its V
CC
capacitor
and keeps activating the MOSFET ON and OFF with a peak
current limited by Rsense. Unfortunately, if the quality
coefficient Q of the resonating network formed by Lp and
Cbulk is low (e.g. the MOSFET Rdson + Rsense are small),
conditions are met to make the circuit resonate and thus
negatively bias the controller. Since we are talking about ms
pulses, the amount of injected charge (Q = I * t) immediately
latches the controller that brutally discharges its V
CC
capacitor. If this V
CC
capacitor is of sufficient value, its
stored energy damages the controller. Figure 27 depicts a
typical negative shot occurring on the HV pin where the
brutal V
CC
discharge testifies for latchup.
相關(guān)PDF資料
PDF描述
NCP1217D100R2G Enhanced PWM Current−Mode Controller for High−Power Universal Off−Line Supplies
NCP1217P100G Enhanced PWM Current−Mode Controller for High−Power Universal Off−Line Supplies
NCP1217P133G Enhanced PWM Current−Mode Controller for High−Power Universal Off−Line Supplies
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
NCP1217D100R2 功能描述:電流型 PWM 控制器 Enhanced Current RoHS:否 制造商:Texas Instruments 開(kāi)關(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)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(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14
NCP1217D100R2G 功能描述:電流型 PWM 控制器 Enhanced Current Mode PWM RoHS:否 制造商:Texas Instruments 開(kāi)關(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)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(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14
NCP1217D100R2G 制造商:ON Semiconductor 功能描述:Pulse Width Modulation (PWM) Controller
NCP1217D133R2 功能描述:電流型 PWM 控制器 Enhanced Current RoHS:否 制造商:Texas Instruments 開(kāi)關(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)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(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14
NCP1217D133R2G 功能描述:電流型 PWM 控制器 Enhanced Current Mode PWM RoHS:否 制造商:Texas Instruments 開(kāi)關(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)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(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14
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