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參數(shù)資料
| 型號： | NCP1200D |
| 廠商： | ON SEMICONDUCTOR |
| 英文描述： | PWM Current-Mode Controller for Universal Off-Line Supplies Featuring Low Standby Power |
| 中文描述： | PWM電流模式控制器的通用離線用品，具有低待機功耗 |
| 文件頁數(shù)： | 8/16頁 |
| 文件大?。?/td> | 136K |
| 代理商： | NCP1200D |
NCP1200A
http://onsemi.com
8
Figure 16. A simple diode naturally reduces the average voltage on pin 8
8
7
6
5
1
2
3
4
mains
Cbulk
HV
Skipping Cycle Mode
The NCP1200A automatically skips switching cycles
when the output power demand drops below a given level.
This is accomplished by monitoring the FB pin. In normal
operation, pin 2 imposes a peak current accordingly to the
load value. If the load demand decreases, the internal loop
asks for less peak current. When this setpoint reaches a
determined level, the IC prevents the current from
decreasing further down and starts to blank the output
pulses: the IC enters the socalled skip cycle mode, also
named controlled burst operation. The power transfer now
depends upon the width of the pulse bunches (Figure 18).
Suppose we have the following component values:
Lp, primary inductance = 1 mH
F
SW
, switching frequency = 61 kHz
Ip skip = 200 mA (or 333 mV/R
SENSE
)
The theoretical power transfer is therefore:
1
2
If this IC enters skip cycle mode with a bunch length of
20 ms over a recurrent period of 100 ms, then the total
power transfer is: 1.2
.
0.2 = 240 mW.
Lp
Ip
2
FSW
1.2 W
To better understand how this skip cycle mode takes place,
a look at the operation mode versus the FB level
immediately gives the necessary insight:
Figure 17.
SKIP CYCLE OPERATION
I
P(min)
= 333 mV/R
SENSE
NORMAL CURRENT
MODE OPERATION
FB
1 V
4.2 V, FB Pin Open
3.2 V, Upper
Dynamic Range
When FB is above the skip cycle threshold (1 V by
default), the peak current cannot exceed 1 V/R
SENSE
. When
the IC enters the skip cycle mode, the peak current cannot go
below Vpin1 / 3.3. The user still has the flexibility to alter
this 1 V by either shunting pin 1 to ground through a resistor
or raising it through a resistor up to the desired level.
Grounding pin 1 permanently invalidates the skip cycle
operation.
Power P1
Power P2
Power P3
Figure 18. Output Pulses at Various Power Levels (X = 5.0 s/div) P1
P2
P3
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| NCP1200AD100R2 | PWM Current-Mode Controller for Universal Off-Line Supplies Featuring Low Standby Power |
| NCP1200AD100R2G | PWM Current-Mode Controller for Universal Off-Line Supplies Featuring Low Standby Power |
| NCP1200AD40R2 | PWM Current-Mode Controller for Universal Off-Line Supplies Featuring Low Standby Power |
| NCP1200 | PWM Current-Mode Controller for Low-Power Universal Off-Line Supplies |
| NCP1200D100R2 | PWM Current-Mode Controller for Low-Power Universal Off-Line Supplies |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| NCP1200D100R | 制造商:Rochester Electronics LLC 功能描述: 制造商:ON Semiconductor 功能描述: |
| NCP1200D100R2 | 功能描述:電流型 PWM 控制器 100KHz Current Mode 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 |
| NCP1200D100R2G | 功能描述:電流型 PWM 控制器 100KHz Current Mode SMPS 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 |
| NCP1200D100R2G | 制造商:ON Semiconductor 功能描述:Pulse Width Modulation (PWM) Controller |
| NCP1200D40R2 | 功能描述:電流型 PWM 控制器 40KHz Current Mode 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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