- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄364677 > AN-995A Electronic Ballasts Using the Cost-Saving IR215X Drivers(153.99 k) PDF資料下載
參數(shù)資料
| 型號(hào)： | AN-995A |
| 英文描述： | Electronic Ballasts Using the Cost-Saving IR215X Drivers(153.99 k) |
| 中文描述： | 使用電子鎮(zhèn)流器的成本節(jié)約IR215X驅(qū)動(dòng)器（153.99十一） |
| 文件頁數(shù)： | 4/10頁 |
| 文件大?。?/td> | 153K |
| 代理商： | AN-995A |
Application
Notes
C-62
C
ONTROL
I
NTEGRATED
C
IRCUIT
D
ESIGNERS’
M
ANUAL
from the fast wave fronts, a 0.5W snubber of 10
and
0.001 μF is used to reduce the switch times to approxi-
mately 0.5 μs. Note that there is a built-in dead time of
1.2 μs in the IR2151 driver to prevent shoot-through cur-
rents in the half-bridge.
The fluorescent lamps are operated in parallel, each
with its own L-C resonant circuit. Up to four tube cir-
cuits can be driven from a single pair of MOSFETs sized
to suit the power level.
The reactance values for the lamp circuit are selected
from L-C reactance tables or from the equation for series
resonance:
f =
1
2
LC
π
(4)
The Q of the lamp circuits is rather low because of the
need for operation from a fixed frequency which, of
course, can vary because of R
and C
tolerances. Fluo-
rescent lamps do not normally require very high striking
voltages so a Q of 2 or 3 is sufficient. ‘Flat Q’ curves
tend to result from larger inductors and small capacitor
ratios where:
Q =
2 fL
R
(5)
and R tends to be larger as more turns are used.
Soft-starting with tube filament pre-heating can be
cheaply incorporated by using P.T.C. thermistors across
each lamp. In this way, the voltage across the lamp
gradually increases as the P.T.C. self-heats until finally
the striking voltage with hot filaments is reached and the
lamp strikes.
High Power Factor
The circuit shown in figure 4 is a passive power factor
improvement (no active boost circuit) and is applicable
to low power ballasts such as compact fluorescent. It
suffers from the disadvantage of low DC rectified output
voltage and results in a crest factor of about 2.
Note that a crest factor standard not exceeding 1.7 is
recommended by fluorescent lamp manufacturers to re-
alize the maximum life projections of 20,000 hours for
these lamps.
Crest Factor =
Peak Current
RMS Current
If the ballast delivers a pure sine wave of voltage and
current to the lamp, the crest factor would be
2
. In an
electronic ballast, a DC bus voltage is derived from a
mains frequency rectifier and is filtered by means of an
electrolytic capacitor. The 2x line frequency ripple volt-
age on the DC bus gives rise to additional ripple currents
in the lamp. Even if the lamp current is sinusoidal (crest
factor 1.414) the mains-related ripple adds to the peak
current value and causes the crest factor to increase. Re-
ferring to the waveforms of figure 5, it is clear that the
ripple voltage amplitude is V
P
/2 which results in a crest
factor of approximately 2.
What is needed, therefore, is a power factor correction
using active control to minimize current ripple and stabi-
lize the DC bus voltage. Boost regulator correction cir-
0.22
μ
F
250 VAC
P.F. > 0.96 LAG
10
μ
F
200v
1N4007
47
1W
1N
4007
Note: The addition of 47
improves P.F. from0.94 to 0.96
resistor
4 x 1N4007
230 VAC
0.22
μ
F
250 VAC
10
μ
F
200v
40W Output
+
-
1N4007
Figure 4.
Passive high power factor rectifier/filter
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| AN0416NA | TRANSISTOR | MOSFET | ARRAY | N-CHANNEL | 160V V(BR)DSS | 30MA I(D) | DIP |
| AN0416ND | TRANSISTOR | MOSFET | ARRAY | N-CHANNEL | 160V V(BR)DSS | 25MA I(D) | CHIP |
| AN0416WG | TRANSISTOR | MOSFET | ARRAY | N-CHANNEL | 160V V(BR)DSS | 30MA I(D) | SO |
| AN0420NA | TRANSISTOR | MOSFET | ARRAY | N-CHANNEL | 200V V(BR)DSS | 30MA I(D) | DIP |
| AN0420ND | TRANSISTOR | MOSFET | ARRAY | N-CHANNEL | 200V V(BR)DSS | 25MA I(D) | CHIP |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| AN-996 | 制造商:FAIRCHILD 制造商全稱:Fairchild Semiconductor 功能描述:Using the Fairchild FST Bus Switch as a 5V to 3V Translator |
| AN9C10A | 制造商: 功能描述: 制造商:undefined 功能描述: |
| AN9D | 制造商:PANASONIC 制造商全稱:Panasonic Semiconductor 功能描述:Analog master slice IC series |
| AN9DA00 | 制造商:PANASONIC 制造商全稱:Panasonic Semiconductor 功能描述:Analog master slice IC series |
| AN9DB00 | 制造商:PANASONIC 制造商全稱:Panasonic Semiconductor 功能描述:Analog master slice IC series |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。