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參數(shù)資料
| 型號： | NCP1205 |
| 廠商： | ON SEMICONDUCTOR |
| 英文描述： | Single Ended PWM Controller Featuring QR Operation and Soft Frequency Foldback |
| 中文描述： | 單端PWM控制器具有名冊操作和軟頻率折返 |
| 文件頁數(shù)： | 12/20頁 |
| 文件大?。?/td> | 163K |
| 代理商： | NCP1205 |
NCP1205
http://onsemi.com
12
1. In BCM, every time the 65 mV line is crossed, the
switch is immediately turned–on. By accounting for
the internal Demag pin capacitance (10–15 pF
typical), you can introduce a fixed delay, which,
combined to the propagation delay, allows to precisely
re–start in the drain–source valley (minimum voltage
to reduce capacitive losses).
2. When the IC enters VFM, the VCO delivers a pulse
which is internally latched. As soon as the
demagnetization pulse appears, the logic re–starts the
MOSFET.
3. As can be seen from Figure 13, the parasitic
oscillations on the drain are subject to a natural
damping, mainly imputed to ohmic losses. At a given
point, the demag activity on the auxiliary winding
becomes too low to be detected. To avoid any re–start
problem, the TY72001 features an internal 4.0
μ
s
timeout delay. This timeout runs after each demag
pulse. If within 4.0
μ
s further to a demag pulse no
activity is detected, an internal signal is combined
with the VCO to actually re–start the MOSFET
(synchronized with Ct).
Error Amplifier and Fault Detection
The NCP1205 features an internal error amplifier solely
used to detect an overcurrent problem. The application
assumes that all the error gain associated with the precise
reference level is located on the secondary side of the SMPS.
Various solutions can be purposely implemented such as the
TL431 or a dedicated circuit like the MC33341. In the
NCP1205, the internal OPAMP is used to create a virtual
ground permanently biased at 2.5 V (Figure 14), an internal
reference level. By monitoring this virtual ground further
called V(–), we have the possibility to confirm the good
behavior of the loop. If by any mean the loop is broken
(shorted optocoupler, open LED etc.) or the regulation
cannot be reached (true output short–circuit), the OPAMP
network is adjusted in order to no longer be able to ensure
the 2.5 V virtual point V(–). If V(–) passes down the 1.5 V
level (e.g. output shorted) for a time longer than 128 ms, then
the pulses are stopped for 8 x 128 ms. The IC enters a kind
of burst mode with bunch of pulses lasting 128 ms and
repeating every 8 x 128 ms. If the loop is restored within the
8 x 128 ms period, then the pulses are back again on the
output drive (synchronized with UVLO
H
).
Figure 14. Core Reset Detection is done through
an Auxiliary Winding Operated in Forward
2
750.0 U
754.0 U
758.0 U
762.0 U
766.0 U
I
P
= 0
Auxiliary Level
Restart when Demag is too low
65 mV
0 V
Valley
Switching
Drain Level
Possible Demag
4
μ
s
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| NCP1205/D | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Single Ended PWM Controller Featuring QR Operation and Soft Frequency Foldback |
| NCP1205_06 | 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:Single Ended PWM Controller Featuring QR Operation and Soft Frequency Foldback |
| NCP1205DR2 | 功能描述:IC CTRLR PWM CM OVP HV 16SOIC RoHS:否 類別:集成電路 (IC) >> PMIC - AC-DC 轉換器，離線開關 系列:- 標準包裝: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） 供應商設備封裝:8-MDIP 包裝:Digi-Reel® 其它名稱:FSL206MRBNFSDKR |
| NCP1205DR2G | 功能描述:電流型 PWM 控制器 Single Ended Quasi Resonant PWM 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(shù)量:1 最大工作溫度:+ 105 C 安裝風格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
| NCP1205P | 功能描述:電流型 PWM 控制器 Single Ended Quasi 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(shù)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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