- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄377970 > ML4813 (Fairchild Semiconductor Corporation) Flyback Power Factor Controller(倒轉(zhuǎn)功率因數(shù)控制器) PDF資料下載
參數(shù)資料
| 型號(hào)： | ML4813 |
| 廠商： | Fairchild Semiconductor Corporation |
| 元件分類： | 基準(zhǔn)電壓源/電流源 |
| 英文描述： | Flyback Power Factor Controller(倒轉(zhuǎn)功率因數(shù)控制器) |
| 中文描述： | 反激式功率因數(shù)控制器（倒轉(zhuǎn)功率因數(shù)控制器） |
| 文件頁數(shù)： | 12/15頁 |
| 文件大?。?/td> | 265K |
| 代理商： | ML4813 |
ML4813
12
OFF-LINE START-UP AND BIAS SUPPLY GENERATION
A fast starting circuit is included in Figure 9. MOSFET Q2
quickly charges the ML4813 V
CC
capacitor (C8) when the
supply is initially turned on. This allows the supply to
come on less than 1 second after AC power is applied. A
simpler start-up circuit may be used which replaces the
active circuit with a 39k
W,
2W resistor but starts more
slowly (up to 15 seconds under low line conditions).
Systems which do not require quick starting can reduce
cost with the latter start-up method.
POWER FACTOR ENHANCEMENT
Some combinations of line and load may exhibit
distortion of the input current waveform. This distortion is
usually caused by the inductor "ringing" with the C
DS
of
the power MOSFET, resulting in a non-zero inductor
current at the beginning of the next cycle. This ringing
can be dampened by using R2 and D7 as shown in Figure
9. Applications which can get by with slightly worse
power factor can eliminate these components.
ADJUSTING THE OUTPUT VOLTAGE
The error amplifier creates an error voltage from the
difference between the output voltage presented at OA
OUT and the 5V internal reference. Since the output
voltage is not ground referenced, the ML4813's internal
op amp is connected as an instrumentation amplifier as
shown in Figure 11.
The output voltage is set by resistors which determine the
relationship between (V
OUT+
- V
OUT-
) and the output of
the op amp. For the following discussion, R15' = R15 +
R16 and R14' = R13 + R14. The differencing amplifier
depends on the following relationships:
R14'= R15'
R12 = R25 + (R17 || R18)
Then:
V
V
17
R
R
R
R
R
R25
+
’
R
R
OUT
=
+
+
+
5
18
18
15
15
14
12
1
’
’
(20)
Since R25 is a low value compared to R15', the second
term reduces to approximately 1. The third term is set at
approximately 200. Equation (20) can be reduced to:
V
R
R
R
OUT
@
+
1000
18
17
18
(21)
The overvoltage comparator has a threshold that is set for
1.12 x V
OUT
when OVP and OA OUT are connected
directly. Figure 12 shows the connection for setting an
OVP trip point higher than 1.12 x V
OUT
, where:
V
V
R
R
R
OVP
OUT
A
B
B
@
+
112
.
(22)
APPLICATIONS
(Continued)
OA+
OA-
OA OUT
+
–
VOUT+
VOUT-
TO
ERROR AMP
AND OVP
R14'
R15'
R17
R18
R12
R25
Figure 11. Ground Referencing the Op Amp Output
Figure 12. Setting OVP at > 1.12 x V
OUT
Figure 13. Setting OVP at < 1.12 x V
OUT
OVP
OA OUT
RA
RB
ML4813
OA OUT
R24
RD
OVP
VFB
COMP
C13
ML4813
Figure 15 shows OVP set for a voltage lower than 1.12 x
V
OUT
where:
V
V
RD
R24
RD
OVP
OUT
@
+
112
.
(23)
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| ML4819 | Power Factor and PWM Controller “Combo” |
| ML4819CP | Power Factor and PWM Controller “Combo” |
| ML4821 | Power Factor Controller |
| ML4821CP | Power Factor Controller |
| ML4821CS | Power Factor Controller |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ML4813CP | 制造商:MICRO-LINEAR 制造商全稱:MICRO-LINEAR 功能描述:Flyback Power Factor Controller |
| ML4813CS | 制造商:MICRO-LINEAR 制造商全稱:MICRO-LINEAR 功能描述:Flyback Power Factor Controller |
| ML4813IP | 制造商:MICRO-LINEAR 制造商全稱:MICRO-LINEAR 功能描述:Flyback Power Factor Controller |
| ML4813IS | 制造商:MICRO-LINEAR 制造商全稱:MICRO-LINEAR 功能描述:Flyback Power Factor Controller |
| ML4818 | 制造商:MICRO-LINEAR 制造商全稱:MICRO-LINEAR 功能描述:Phase Modulation/Soft Switching Controller |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。