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參數(shù)資料
| 型號： | NCP1207DR2G |
| 廠商： | ON SEMICONDUCTOR |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | PWM Current-Mode Controller for Free Running Quasi-Resonant Operation |
| 中文描述： | 0.5 A SWITCHING CONTROLLER, PDSO8 |
| 封裝： | LEAD FREE, SOIC-8 |
| 文件頁數(shù)： | 11/18頁 |
| 文件大?。?/td> | 202K |
| 代理商： | NCP1207DR2G |
NCP1207
http://onsemi.com
11
Demagnetization Detection
The core reset detection is done by monitoring the voltage
activity on the auxiliary winding. This voltage features a
FLYBACK polarity. The typical detection level is fixed at
50 mV as exemplified by Figure 21.
POSSIBLE
RESTARTS
50 mV
Figure 21. Core reset detection is done through a
dedicated auxiliary winding monitoring
7.0
5.0
3.0
1.0
1.0
0 V
D
Figure 22. Internal Pad Implementation
An internal timer prevents any restart within 8.0 s
further to the driver goinglow transition. This prevents the
switching frequency to exceed (1 / (T
ON
+ 8.0 s)) but also
avoid false leakage inductance tripping at turnoff. In some
cases, the leakage inductance kick is so energetic, that a
slight filtering is necessary.
The 1207 demagnetization detection pad features a
specific component arrangement as detailed by Figure 22. 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 R
dem
, a restart delay is created
and the possibility to switch right in the drainsource wave
exists. This guarantees QR operation with all the associated
benefits (low EMI, no turnon losses etc.). R
dem
should be
calculated to limit the maximum current flowing through
pin 1 to less than +3 mA/2 mA. If during turnon, the
auxiliary winding delivers 30 V (at the highest line level),
then the minimum R
dem
value is defined by:
(30 V + 0.7 V) / 2 mA = 14.6 k .
This value will be further increased to introduce a restart
delay and also a slight filtering in case of high leakage
energy.
Figure 23 portrays a typical V
DS
shot at nominal output
power.
TO INTERNAL
COMPARATOR
Aux
R
esd
R
dem
ESD2
ESD1
4
5
2
4
1
R
esd
+ R
int
= 28 k
R
int
3
1
Figure 23. The NCP1207 Operates in
Borderline / Critical Operation
400
300
200
100
0
D
Overvoltage Protection
The overvoltage protection works by sampling the plateau
voltage 4.5 s after the turnoff sequence. This delay
guarantees a clean plateau, providing that the leakage
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 24 shows where the sampling occurs on the auxiliary
winding.
Figure 24. A voltage sample is taken 4.5 s after
the turnoff sequence
8.0
6.0
4.0
2.0
0
SAMPLING HERE
D
4.5 s
When an OVP condition has been detected, the NCP1207
enters a latchoff phase and stops all switching operations.
The controller stays fully latched in this position and the
DSS is still active, keeping the V
CC
between 5.3 V/12 V as
in normal operations. This state lasts until the V
CC
is cycled
down 4 V, e.g. when the user unplugs the power supply from
the mains outlet.
By default, the OVP comparator is biased to a 5 V
reference level and pin 1 is routed via a divide by 1.44
network. As a result, when V
pin1
reaches 7.2 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 7.2 V level, or insert a resistor from
pin1 to ground to cope with your design requirement.
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| NCP1207P | 功能描述:IC CTRLR PWM CM OVP OCP HV 8DIP RoHS:否 類別:集成電路 (IC) >> PMIC - AC-DC 轉(zhuǎn)換器，離線開關(guān) 系列:- 標(biāo)準(zhǔn)包裝:1 系列:FPS™ 輸出隔離:隔離 頻率范圍:61kHz ~ 73kHz 輸入電壓:8 V ~ 26 V 輸出電壓:650V 功率（瓦特）:12W 工作溫度:-40°C ~ 115°C 封裝/外殼:8-DIP（0.300"，7.62mm） 供應(yīng)商設(shè)備封裝:8-MDIP 包裝:Digi-Reel® 其它名稱:FSL206MRBNFSDKR |
| NCP1207PG | 功能描述:IC CTRLR PWM CM OVP OCP HV 8DIP RoHS:是 類別:集成電路 (IC) >> PMIC - AC-DC 轉(zhuǎn)換器，離線開關(guān) 系列:- 標(biāo)準(zhǔn)包裝:1 系列:FPS™ 輸出隔離:隔離 頻率范圍:61kHz ~ 73kHz 輸入電壓:8 V ~ 26 V 輸出電壓:650V 功率（瓦特）:12W 工作溫度:-40°C ~ 115°C 封裝/外殼:8-DIP（0.300"，7.62mm） 供應(yīng)商設(shè)備封裝:8-MDIP 包裝:Digi-Reel® 其它名稱:FSL206MRBNFSDKR |
| NCP1209/D | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:PWM Voltage Mode Controller |
| NCP1212 | 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:Current Mode PWM Controller for Both Forward and Flyback Converters |
| NCP1212/D | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Current Mode PWM Controller for Both Forward and Flyback Converters |
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