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參數(shù)資料
| 型號： | NCP1239 |
| 廠商： | ON SEMICONDUCTOR |
| 英文描述： | Low−Standby High Performance PWM Controller |
| 文件頁數(shù)： | 31/38頁 |
| 文件大?。?/td> | 1145K |
| 代理商： | NCP1239 |
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NCP1239
http://onsemi.com
31
SoftStart
The NCP1239 features an internal softstart activated
during the Power On sequence (PON). As soon as V
CC
reaches 16.4 V, the current setpoint is gradually increased
from nearly zero up to the maximum clamping level (e.g.
0.9 V/Rsense). This situation lasts a programmable time that
is adjusted by the Pin 6 capacitor (7.5 ms typically with
C
pin6
= 390 nF). Further to that time period, the current
setpoint is blocked to 0.9 V/Rsense until the supply enters
regulation. The softstart is also activated at each start of the
active phase of fault burst operation. Every restart attempt
is followed by a softstart activation.
Generally speaking, the softstart will be activated when
V
CC
ramps up either from zero (fresh poweron sequence)
or 6.9 V, the latchoff threshold after an overload detection
(OVL) for instance. Figure 51 shows the softstart behavior.
The time scales are purposely shifted to offer a better zoom
portion.
Figure 51.
Softstart is activated during a startup sequence or an OVL condition
16.4V
6.9V
Internal Ramp Compensation
Ramp compensation is a known mean to cure
subharmonic oscillations. These oscillations take place at
half the switching frequency and occur only during
Continuous Conduction Mode (CCM) with a dutycycle
greater than 50%. To lower the current loop gain, one usually
injects between 50 and 100% of the inductor downslope.
Figure 52 depicts how internally the ramp is generated:
Figure 52.
Inserting a resistor in series with the current sense
information brings ramp compensation
+
CS
LEB
32k
Rramp
Rsense
from
setpoint
3.2V
0V
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| NCP1239FDR2 | Low−Standby High Performance PWM Controller |
| NCP1239FDR2G | Low−Standby High Performance PWM Controller |
| NCP1239VDR2 | Low−Standby High Performance PWM Controller |
| NCP1239VDR2G | Low−Standby High Performance PWM Controller |
| NCP1271 | Soft−Skip Mode Standby PWM Controller with Adjustable Skip Level and External Latch |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| NCP1239D | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Low-Standby High Performance PWM Controller |
| NCP1239F | 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:AC-DC Offline Switching Controllers/Regulators |
| NCP1239FDR2 | 功能描述:電流型 PWM 控制器 Low Standby Power 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 安裝風格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
| NCP1239FDR2G | 功能描述:電流型 PWM 控制器 Low Standby Power High Performance 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 安裝風格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
| NCP1239V | 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:AC-DC Offline Switching Controllers/Regulators |
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