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參數(shù)資料
| 型號： | NCP1205DR2 |
| 廠商： | ON SEMICONDUCTOR |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Single Ended PWM Controller Featuring QR Operation and Soft Frequency Foldback |
| 中文描述： | SWITCHING CONTROLLER, 125 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封裝： | SOIC-16 |
| 文件頁數(shù)： | 11/17頁 |
| 文件大小： | 277K |
| 代理商： | NCP1205DR2 |
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 11. 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 12. 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
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| NCP1205P | Single Ended PWM Controller Featuring QR Operation and Soft Frequency Foldback |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| 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(guān)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(fēng)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(guān)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(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
| NCP1205P2 | 功能描述:電流型 PWM 控制器 Single Ended Quasi RoHS:否 制造商:Texas Instruments 開關(guān)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(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
| NCP1205P2G | 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(guān)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(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
| NCP1205PG | 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(guān)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(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
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