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參數(shù)資料
| 型號： | NCP1212 |
| 廠商： | ON SEMICONDUCTOR |
| 英文描述： | Current Mode PWM Controller for Both Forward and Flyback Converters |
| 中文描述： | 電流模式PWM控制器正向和反激式轉(zhuǎn)換器 |
| 文件頁數(shù)： | 17/22頁 |
| 文件大?。?/td> | 200K |
| 代理商： | NCP1212 |
NCP1212
http://onsemi.com
17
I
SD
I
SS
is the internal current source for C
SS
discharging,
20 A typical.
The discharging time for 0.22 F SoftStart capacitor is:
0.22 F
(5.0 V
20 A
TDIS
0.6 V
0.5 V)
42.9 ms
The discharging waveform on SS/DMAX pin is shown in
Figure 41. The discharging time from 4.0 V to 0.6 V is
measured as 36 ms from Figure 41. By interpolation,
discharging time can be estimated as about 41.3 ms when
output is overload which agreed with the calculated result.
Figure 41. SS/DMAX Pin Discharging Waveform
36 ms
3.4 V
2. Determine the PWM Switching Frequency
The switching waveform is generated by the action
of charging and discharging by internal current
sources to a capacitor connected at C
T
, pin 4. The
relationship of the switching frequency and the value
of C
T
is governed by the equation below:
FSW
Ichg
D
CT
(Vth
1)
where:
I
chg
is the charging current to C
T
, 278 A typical;
D is the selected Maximum Duty Cycle, 48% or
82%;
C
T
is the capacitor connected to C
T
pin;
V
th
is the threshold voltage for different Maximum
Duty Cycle selection, 2.5 V for 48% Maximum
Duty Cycle and 3.8 V for 82% Maximum Duty
Cycle.
The Switching Frequency against C
T
is shown in
Figure 31 to help the designers to determine the capacitance
for their selected switching frequency.
3. Determine the BOK Thresholds
Brownout detect thresholds are determined by a
resistors network that monitors part of the bulk
capacitor voltage at BOK pin. Equations below
illustrate the calculation of the resistors value for the
network.
RUpper
RLower
(VBulk_H
VBulk_L)
45 A
RLower
[1.21 V(VBulk_H
(45 A
VBulk_L)]
VBulk_H)
Where V
Bulk_H
and V
Bulk_L
are the desired upper
and lower bulk capacitor voltage for brownout
detection.
Assume V
Bulk_H
= 212 Vdc and V
Bulk_L
= 186 Vdc,
select 3.3 k for R
Lower
then R
Upper
can be
calculated to be 576 k .
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PDF描述 |
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| NCP1212PG | Current Mode PWM Controller for Both Forward and Flyback Converters |
| NCP1212DR2 | Current Mode PWM Controller for Both Forward and Flyback Converters |
| NCP1212P | Current Mode PWM Controller for Both Forward and Flyback Converters |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| NCP1212/D | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Current Mode PWM Controller for Both Forward and Flyback Converters |
| NCP1212_05 | 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:Current Mode PWM Controller for Both Forward and Flyback Converters |
| NCP1212DR2 | 功能描述:電流型 PWM 控制器 High Performance 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 |
| NCP1212DR2G | 功能描述:電流型 PWM 控制器 High Performance Current Mode 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 |
| NCP1212P | 功能描述:交流/直流開關(guān)轉(zhuǎn)換器 High Performance RoHS:否 制造商:STMicroelectronics 輸出電壓:800 V 輸入/電源電壓（最大值）:23.5 V 輸入/電源電壓（最小值）:11.5 V 開關(guān)頻率:115 kHz 電源電流:1.6 mA 工作溫度范圍:- 40 C to + 150 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SSO-10 封裝:Reel |
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