- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄363216 > NCP1205 (ON SEMICONDUCTOR) Single Ended PWM Controller Featuring QR Operation and Soft Frequency Foldback PDF資料下載
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)： | 11/20頁 |
| 文件大?。?/td> | 163K |
| 代理商： | NCP1205 |
NCP1205
http://onsemi.com
11
If we now enter this formula into a spreadsheet, we can easily plot the switching frequency versus the output power demand:
Figure 12. A Typical Behavior of Free Running Systems
with a Smooth Frequency Foldback with the NCP1205
150000
0
250000
50000
100000
200000
0
15
10
5
S
Transition
BCM to VFM
OUTPUT POWER (W)
20
Fmax
Fmax
V
CO
Action
The typical above diagram shows how the frequency
moves with the output power demand. The components used
for the simulation were: Vin = 300 V, Lp = 6.5 mH,
Vout = 10 V, Np/Ns = 12.
The red line indicates where the maximum frequency is
clamped. At this time, the VCO takes over and decreases the
switching frequency to the minimum value.
VCO Operation
The VCO is controlled from the Verr voltage. For Verr
levels
above
1.0 V, the VCO frequency remains unchanged
at 125 kHz. As soon as Verr starts to decrease below 1.0 V,
the VCO frequency decreases with a typical
small–signal
slope of –175 kHz/mV @ Verr = 500 mV down to
zero (typically at FB
≈
3.3 V). The demagnetization
synchronization is however kept when the Toff expands.
The maximum switching frequency can be altered by
adjusting the Ct capacitor on pin 5. The 125 kHz maximum
operation ensures that the fundamental component stays
external
from
the
international
specification beginning.
The following drawing explains the philosophy behind
the idea:
EMI
CISPR–22
Figure 13. When the Power Demand goes Low, the Peak Current is Frozen and the Frequency Decreases
3 V
1 V
0.75 V
Peak Current is Fixed
Peak current
can change
V
CO
Frequency
is Fixed at 130 kHz
V
CO
Frequency
can Decrease
Internal V
err
BCM Mode
Zero Crossing Detector
To detect the zero primary current, we make use of an
auxiliary winding. By coupling this winding to the primary,
we have a voltage image of the flux activity in the core.
Figure 13 details the shape of the signal in BCM.
The auxiliary winding for demagnetization needs to
be wired in Forward mode. However, the application
note describes an alternative solution showing how to wire
the winding in Flyback as well. As Figure 13 depicts, when
the MOSFET closes, the auxiliary winding delivers
(Naux/Np
.
Vin). At the switch opening, we couple the
auxiliary winding to the main output power winding and
thus deliver: (–Naux/Ns
.
Vout). When DCM occurs, the
ringing also takes place on the auxiliary winding. As soon
as the level crosses–up the internal reference level
(65 mV), a signal is internally sent to re–start the MOSFET.
Three different conditions can occur:
相關PDF資料 |
PDF描述 |
|---|---|
| NCP1207APG | PWM Current−Mode Controller for Free Running Quasi−Resonant Operation |
| NCP1207AP | PWM Current-Mode Controller for Free Running Quasi-Resonant Operation |
| NCP1207ADR2 | PWM Current-Mode Controller for Free Running Quasi-Resonant Operation |
| NCP1207ADR2G | PWM Current-Mode Controller for Free Running Quasi-Resonant Operation |
| NCP1207A | PWM Current Mode Controller for Free Running Quasi Resonant Operation(電流模式控制的PWM控制器，用于自由振蕩的“準諧振”操作) |
相關代理商/技術(shù)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(zhuǎn)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 |
發(fā)布緊急采購，3分鐘左右您將得到回復。