- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄363216 > NCP1212 (ON SEMICONDUCTOR) Current Mode PWM Controller for Both Forward and Flyback Converters PDF資料下載
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)： | 12/22頁 |
| 文件大?。?/td> | 200K |
| 代理商： | NCP1212 |
NCP1212
http://onsemi.com
12
Current Sense Section
The current sense pin, CS detects the voltage drop across
a current sensing resistor, R
sense
connected in between the
power MOSFET and Ground. In most cases, a narrow spike
on the leading edge of the current waveform can be observed
and may cause the power supply to exhibit an instability
when the output is lightly loaded. The spike is due to the
power transformer interwinding capacitance and output
rectifier recovery time which are unavoidable. NCP1212
provides a 300 ns Leading Edge Blanking block to shield off
the spike. With the Leading Edge Blanking function, the CS
pin is not sensitive to the power switch turnon noise and
spikes, practically in most applications, no filtering network
is required.
In normal operation, voltage developed at the current
sense input is compared with the level shifted control input
voltage and an internal Current Limit Threshold, V
CS
. In
case the CS input exceeds the Current Limit Threshold,
which is 1.0 V (typ.) in NCP1212, the gate driver output will
be forced to turn off immediately.
Thus the maximum allowable peak current is given by the
following equation:
Ipk(max)
1 V
Rsense
SoftStart and Maximum Duty Selection
NCP1212 includes an internal SoftStart function to
simplify designer’s job hence make this device easy to use.
During the startup phase, a constant current source of 8.0 A
flows out of the SS/DMAX pin once V
CC
attains the
minimum startup voltage. The capacitor connected at
SS/DMAX pin is slowly charged up and the voltage
developed plus one diode drop, V
SST
is compared with the
sawtooth waveform, C
T
from the internal oscillator as
shown in Figure 34. Whenever C
T
voltage is higher than
V
SST
, gate driver output will be turned off. Since V
SST
rises
slowly and it controls the output duty gradually increases as
shown in Figure 35. The minimum C
T
voltage is at 1.0 V,
hence there is no output before SS/DMAX pin attains about
0.4 V (1.0 V–1 diode drop). SoftStart block will have no
effect to the PWM operation once V
SST
reaches 3.2 V.
Figure 34. SoftStart Operation
S
Q
Q
+
F/F
Overload
Enable
Reset
+
3.2 V
From C
T
Vsst
+5 V
8
A
Shutdown
SS/DMAX
NCP1212
Duty Cycle Control
C
SS
Figure 35. Output Pulse Duty Cycle Depends on the SS/DMAX Pin Voltage
V
SST
V
DRV
C
T
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| 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 |
| NCP1215(中文) | Low Cost Variable OFF Time Switched Mode Power Supply Controller(低成本可變關(guān)閉時間開關(guān)模式電源控制器) |
| NCP1215ADR2 | Low Cost Variable OFF Time Switched Mode Power Supply Controller |
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 |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。