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參數(shù)資料
| 型號： | SP4424CN |
| 英文描述： | Electroluminescent Lamp Driver Dual Oscillators |
| 中文描述： | 電致發(fā)光燈驅(qū)動器雙振蕩器 |
| 文件頁數(shù)： | 4/12頁 |
| 文件大?。?/td> | 119K |
| 代理商： | SP4424CN |
SP4424DS/16
SP4424 Electroluminescent Lamp Driver
4
Copyright 2000 Sipex Corporation
linear rate. As the current in the inductor builds up,
the voltage across the inductor will decrease due to
the resistance of the coil and the "ON" resistance
of the switch: V
=V
-IR
-V
. Since the
voltage across the inductor is decreasing, the current
ramp-rate also decreases which reduces the current
in the coil at the end of t
the energy stored in the
inductor per coil cycle and therefore the light
output. The other important issue is that maximum
current (saturation current) in the coil is set by the
design and manufacturer of the coil. If the
parameters of the application such as V
, L,
RL or ton cause the current in the coil to increase
beyond its rated I
, excessive heat will be
generated and the power efficiency will decrease
with no additional light output. The majority of the
current goes through the coil and typically less
than 3 mA is required for V
of the
SP4424
. V
can range from 2.2V to 5V; it is not necessary that
V
=V
. For example, an unregulated voltage
source (3.3V) can be directly connected to the coil,
while a regulated voltage source (2.85V) can be
connected to the IC V
DD
pin.
Coil performance is also a function of the core
material and wire used -- performance variances
may be noticeable from different coil suppliers.
The Sipex
SP4424
is tested using a 5mH/18
coil
from Hitachi Metals. For suggested coil sources
see
page 9.
The f
signal controls a switch that connects
the end of the coil at pin 3 to ground or to open
circuit. The f
signal is a 75% duty cycle signal.
During the time when the f
COIL
signal is high, the
coil is connected from V
BATTERY
to ground and a
magnetic field is generated in the coil. During
the low part of f
, the ground connection is
switched open, the field collapses and the voltage
generated in the inductor is directed to the high
voltage H-bridge switches. f
will send as many
charge pulses as possible in 1 Lamp Cycle.{Number of
Coil pulses in 1 lamp cycle =}
(see
figure 2
on
page 6
). Each pulse increases the
voltage drop across the lamp in discrete steps. As
the voltage potential approaches its maximum, the
steps become smaller (see
figure 1
on
page 6
).
The H-bridge consists of two SCR structures that
act as high voltage switches. These two switches
control the polarity of the lamp (capacitor) as it is
charged. The SCR switches are controlled by the
f
signal which is the oscillator frequency
divided by 2.
When the energy from the coil is released, a high
voltage spike is created triggering the SCR
switches. The direction of current flow is
determined by which SCR is enabled. One full
cycle of the H-bridge will create a number of
voltage steps from ground to 65V (typical) on pins
4 and 5 which are 180 degrees out of phase (see
figure 3
on
page 6
). A differential view of the
outputs is shown in
figure 4
on
page 6
.
SP4424 Test Circuit
=ON
HON=0V=OFF
0.1
μ
F Low ESR
Decoupling
Capacitor
C
LAMP
HON
V
DD
EL2
C
COIL
V
SS
Coil
EL1
220pF
SP4424
V
IN
=3V
5
+
–
1500pF
55nF
100
Coil Freq.
x
2
}
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| SP4424CU | Electroluminescent Lamp Driver Dual Oscillators |
| SP4424CX | Electroluminescent Lamp Driver Dual Oscillators |
| SP4424NEB | Electroluminescent Lamp Driver Dual Oscillators |
| SP4424UEB | Electroluminescent Lamp Driver Dual Oscillators |
| SP4425Q | Electroluminescent Lamp Driver for Low Noise Applications |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SP4424CU | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Electroluminescent Lamp Driver Dual Oscillators |
| SP4424CX | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Electroluminescent Lamp Driver Dual Oscillators |
| SP4424NEB | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Electroluminescent Lamp Driver Dual Oscillators |
| SP4424UEB | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Electroluminescent Lamp Driver Dual Oscillators |
| SP4425 | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Electroluminescent Lamp Driver Low Voltage Applications |
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