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參數(shù)資料
| 型號： | SP4428 |
| 英文描述： | Electroluminescent Lamp Driver High Drive Capability for Low Voltage Applications |
| 中文描述： | 電致發(fā)光燈驅(qū)動器驅(qū)動能力高低壓應(yīng)用 |
| 文件頁數(shù)： | 4/11頁 |
| 文件大?。?/td> | 107K |
| 代理商： | SP4428 |
SP4428DS/16
SP4428 Electroluminescent Lamp Driver
4
Copyright 2000 Sipex Corporation
energy produced by the coil V
should
represent the largest voltage in the system (up to
the maximum tolerance of the coil) and the coil
should have low resistance; V
= 1.5 VDC
with a 470
μ
H/4.9
coil are typical. The majority
of the current goes through the coil and typically
less than 1mA is required for V
of the
SP4428
.
V
can range from 1.5V to 1.7V; it is not necessary
that V
=V
. Coils are also a function of the
core material and winding used -- performance
variances may be noticeable from different coil
suppliers. The Sipex
SP4428
is final tested using
a 470
μ
H/4.9
coil from Sumida. 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 90% duty cycle signal switching
at the oscillator frequency. During the time when
the f
COIL
signal is high, the coil is connected from
V
to ground and a charged magnetic field is
created in the coil. During the low part of f
, the
ground connection is switched open, the field
collapses and the energy in the inductor is forced
to flow toward the lamp. f
will send 32 of these
charge pulses every half cycle (see
figure 2
on
page 7
) to the lamp, 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 7
).
The H-bridge consists of two SCR structures that
act as high voltage switches. These two switches
control the polarity of how the lamp is charged.
The SCR switches are controlled by the f
signal which is the oscillator frequency divided by
64. For a 20kHz oscillator, f
LAMP
=300Hz.
C
Optional
1800pF CAP
LAMP
1
Pager
Application
C
OSC
V
SS
Coil
D1
HON
V
DD
EL1
EL2
0.1
μ
F
5 FtL
1.5 SQ. IN.
Fast
470
H
4.9 Ohms
+
-
1.5 Volt
Battery
180pF
Typical SP4428 Application Circuit
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 voltage step
from ground to 80V (typical) on pins 5 and 6 which
are 180 degrees out of phase with each other
(see
figure 3
on
page 7
). A differential view of the
outputs is shown in
figure 4
on
page 7
. If Line
Noise is of concern it is advisable to add a
decoupling cap at V
DD
.
Electroluminescent Technology
What is electroluminescence
An EL lamp is basically a strip of plastic that is
coated with a phosphorous material which emits
light (fluoresces) when a high voltage (>40V)
which was first applied across it, is removed or
reversed. Long periods of DC voltages applied to
the material tend to breakdown the material and
reduce its lifetime. With these considerations in
mind, the ideal signal to drive an EL lamp is a high
voltage sine wave. Traditional approaches to
achieving this type of waveform included discrete
circuits incorporating a transformer, transistors,
and several resistors and capacitors. This approach
is large and bulky, and cannot be implemented in
most hand held equipment.
Sipex
now offers low
power single chip driver circuits specifically
designed to drive small to medium sized
electroluminescent panels if all that is required is
one external inductor fast recovery diode and two
capacitors.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| SP4428CN | Electroluminescent Lamp Driver High Drive Capability for Low Voltage Applications |
| SP4428NEB | Electroluminescent Lamp Driver High Drive Capability for Low Voltage Applications |
| SP4438UEB | RECTIFIER BRIDGE 25A 100V 300A-ifsm 1.1V-vf 5uA-ir GBPCW 100/TRAY |
| SP4438 | Ultra-Quiet Electroluminescent Lamp Driver For Cellular Phone Applications |
| SP4438EU | Ultra-Quiet Electroluminescent Lamp Driver For Cellular Phone Applications |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SP4428CN | 制造商:Exar Corporation 功能描述:BALLAST/BACKLIGHT CONTROLLER/DRIVER, 8 Pin, Plastic, SOP |
| SP4428NEB | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Electroluminescent Lamp Driver High Drive Capability for Low Voltage Applications |
| SP4438 | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Ultra-Quiet Electroluminescent Lamp Driver For Cellular Phone Applications |
| SP4438EU | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Ultra-Quiet Electroluminescent Lamp Driver For Cellular Phone Applications |
| SP4438UEB | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Ultra-Quiet Electroluminescent Lamp Driver For Cellular Phone Applications |
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