參數(shù)資料
型號(hào)： NCP1207ADR2
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： SOIC-8
文件頁(yè)數(shù)： 10/16頁(yè)
文件大小： 197K
代理商： NCP1207ADR2
NCP1207A
http://onsemi.com
10
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 17.
POSSIBLE
RESTARTS
50 mV
Figure 17. 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 18. Internal Pad Implementation
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
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 18. 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 19 portrays a typical V
DS
shot at nominal output
power.
Figure 19. The NCP1207A 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 20 shows where the sampling occurs on the auxiliary
winding.
Figure 20. 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
NCP1207A 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 pin1 is routed via a divide by 1.44
network. As a result, when Vpin 1 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
Pin 1 to ground to cope with your design requirement.
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
NCP1207ADR2G 功能描述:電流型 PWM 控制器 Quasi Resonant Current Mode PWM RoHS:否 制造商:Texas Instruments 開關(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
NCP1207AP 功能描述:電流型 PWM 控制器 Quasi Resonant RoHS:否 制造商:Texas Instruments 開關(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
NCP1207APG 功能描述:電流型 PWM 控制器 Quasi Resonant Current Mode PWM RoHS:否 制造商:Texas Instruments 開關(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
NCP1207B 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:PWM Current-Mode Controller for Free Running Quasi-Resonant Operation
NCP1207BDR2G 功能描述:電流型 PWM 控制器 ANA QUASI RESNT SMPS RoHS:否 制造商:Texas Instruments 開關(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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