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參數資料
| 型號： | NCP1381 |
| 廠商： | ON SEMICONDUCTOR |
| 英文描述： | Low−Standby High Performance PWM Controller |
| 文件頁數： | 15/26頁 |
| 文件大小： | 559K |
| 代理商： | NCP1381 |
NCP1381
http://onsemi.com
15
As one can observe, the output power runs out of the initial
100 W specification when we enter the high line region. To
cope with this problem, we need to compensate the
controller in such a way that its peak capability gets reduced
at higher input voltages. How much do we need to
compensate the peak excursion We can find the answer by
calculating I
P
= I
PLL
I
PHL
, with V
inLL
= 200 V and V
inHL
= 400 V. With our previous numbers, I
P
= 588 mA. We
therefore need to instruct the controller to reduce its peak
excursion by 588 mA at high line. Otherwise speaking, if we
think in voltages, the CS pin excursion shall drop from 0.8 V
(at low line, the maximum peak is 0.8 / R
S
) to (3.2 0.588).
0.25 = 653 mV at high line. Figure 19 shows the situation at
both line levels. A possible solution lies in offsetting the
current floor by the necessary value, which is, in our case,
0.8 0.653 = 147 mV. The traditional way of doing this goes
through the wiring of a high value resistor to the bulk
capacitor. This unfortunately dissipates heat. The NCP1381
offers a more elegant option since it transforms the voltage
available from the Brownout pin into a fixed current,
routed to the CS pin. That way, we can calculate a resistor
value which, once inserted in series with current sense
voltage image, will create our necessary offset. Figure 20
shows this internal connection:
Figure 20. A Transconductance Amplifiers
Transforms the BO Voltage into a Current
Figure 21. The Compensated Converter Output
Power Response to Input Variations
105
100
95
90
200
250
300
350
400
V
in
, VOLTAGE (V)
P
O
+
V
bulk
G1
80 S
To BO
Comp.
BO
CS
R
sense
To CS Comp.
R
offset
We can now calculate our R
offset
resistor to generate the
necessary static voltage. Suppose that the BO network
divides the bulk voltage by 400 (V
BO
= . V
in
= 0.0025 x
V
in
). Therefore, in presence of a 400 V input voltage, we will
have 1 V on the BO pin. due to the transconductance
amplifier of a 80 S gm, it will turn into a 80 A offset
current. To get our 147 mV, we just divide it by 80 A:
R
offset
= V
offset
/ V
inHL
x . g
m
= 1.8 k .
We can now update Equation 4 with Equation 5, where
the peak current is affected by the variable offset:
PO(Vin) :
0.8
RS
Vin
LP
tP
Vin
gm
Roffset
2
(
(Vin(Vout
VF)))
Vout
VF
Vin
N
(eq. 5)
If we now plot the compensated curve, we obtain
Figure 21 graph. The output power is slightly above what we
were originally shooting for and the total power excursion
is now kept within 15 W.
Overvoltage Protection
The NCP1381 features an overvoltage protection made by
sensing the plateau voltage at the switch turnoff. However,
a sampling delay is introduced to avoid considering the
leakage inductance. When the demagnetization pin goes
above V
demlatch
, the comparator goes high. If this condition
is maintained when the sampling pulse arrives, then a fault
is latched. Figure 22 shows the arrangement and Figure 23
portrays a typical waveform. Once latched, the controller
stops all driving pulses and V
CC
is clamped to 6 V. Reset
occurs when the user unplugs the converter from the mains
and V
CC
reduces below 4 V.
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相關代理商/技術參數 |
參數描述 |
|---|---|
| NCP1381 AM90 WAF | 制造商:ON Semiconductor 功能描述: |
| NCP1381ADAPEVB | 功能描述:BOARD EVAL NCP1381 RoHS:是 類別:編程器，開發系統 >> 評估演示板和套件 系列:* 標準包裝:1 系列:PCI Express® (PCIe) 主要目的:接口，收發器，PCI Express 嵌入式:- 已用 IC / 零件:DS80PCI800 主要屬性:- 次要屬性:- 已供物品:板 |
| NCP1381DR2G | 功能描述:電流型 PWM 控制器 ANA PWM CONTROLLER RoHS:否 制造商:Texas Instruments 開關頻率: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 輸出端數量:1 最大工作溫度:+ 105 C 安裝風格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
| NCP1382DR2G | 功能描述:電流型 PWM 控制器 L-STNDBY PWM CNTRLR RoHS:否 制造商:Texas Instruments 開關頻率: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 輸出端數量:1 最大工作溫度:+ 105 C 安裝風格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
| NCP1392B | 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:High-Voltage Half-Bridge Driver with Inbuilt Oscillator |
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