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參數(shù)資料
| 型號(hào)： | SP4403 |
| 英文描述： | Low Voltage Electroluminescent Lamp Driver |
| 中文描述： | 低電壓電致發(fā)光燈驅(qū)動(dòng)器 |
| 文件頁(yè)數(shù)： | 5/14頁(yè) |
| 文件大?。?/td> | 131K |
| 代理商： | SP4403 |
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5
SP4403DS/05 SP4403 Electroluminescent Lamp Driver
Copyright 2000 Sipex Corporation
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.
All that is required for the EL driver circuitry is
an external inductor and an external capacitor.
Market Applications
Electroluminescent backlighting is ideal when
used with LCD displays, keypads, or other backlit
readouts. Its main use is to illuminate displays in
dim to dark conditions for momentary periods
of time. EL lamps typically consume less power
than LEDs or incandescent bulbs making them
ideal for battery powered products. Also, EL
lamps are able to evenly light an area without
creating any undesirable "hot spots" in the
display.
THEORY OF OPERATION
The
SP4403
is a DC-AC inverter made up of:
1. The Oscillator/Frequency Divider, 2. The
Coil, and 3. The Switched H-bridge Network.
Further details of each element follow.
The Oscillator/Frequency Divider
The oscillator provides the
SP4403
with an
on-chip clock used to control the coil switch
(f
) and the H-bridge network (f
and f
).
Although the oscillator frequency can be varied
to optimize the lamp output, the ratio of f
COIL
/
f
LAMP
will always equal 128.
Figure 1
shows the oscillator output driving the
coil and the output of the oscillator with 7 flip
flops driving the lamp. The suggested oscillator
frequency is 50kHz (R
= 450k
) for f
.
The oscillator output is internally divided down
by 7 flip flops to create a second internal control
signal at 390Hz for f
LAMP
.
The Coil
The supply V
can range from +2.2V to
+4.5V. V
should not exceed the maximum
coil current specification. The majority of the
current goes through the coil and is typically
much greater than I
DD
.
The coil is an external component connected
from V
to pin 3 of the
SP4403
. Energy is
stored in the coil according to the equation
E
=1/2LI
is the product I
= (tON)(VBATT - V
)/L),
where t
is the time it takes for the coil to reach
its peak current, V
is the voltage drop across
the internal NPN switch transistor, and L is the
inductance of the coil. When the NPN transistor
switch is off, the energy is forced through an
internal diode which drives the switched H-
bridge network. This energy recovery is directly
related to the brightness of the EL lamp output.
There are many variations among coils; magnetic
material differences, winding differences and
parasitic capacitances. For suggested coil
suppliers, refer to
Page 7
.
2
where I
, to the first approximation,
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,
50kHz. 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. When the f
signal is LOW, the ground
connection is switched open, the field collapses,
and the energy in the inductor is forced to flow
toward the high voltage H-bridge switches.
f
will send an array of charge pulses (see
Figure 4
) 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 3
).
Figure 2. Typical Application Circuit for the SP4403, Set
for a Square Wave Output with C
INT
= 0.1
μ
F
R
OSC
V
SS
COIL
C
INT
SP4403
V
BATT
C1
0.1
μ
F
OSC
R
L1
470
μ
H
3
6
8
1
7
2
ELEN
1D1
INT
1C
optional device
V
DD
EL2
EL1
EL Lamp
5
4
1C2
*
*
*
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| SP4403EU | Low Voltage Electroluminescent Lamp Driver |
| SP4405UEB | Low Voltage Electroluminescent Lamp Driver with Regulated Output Voltage |
| SP4405 | Low Voltage Electroluminescent Lamp Driver with Regulated Output Voltage |
| SP4405EN | Low Voltage Electroluminescent Lamp Driver with Regulated Output Voltage |
| SP4405EU | Low Voltage Electroluminescent Lamp Driver with Regulated Output Voltage |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SP4403EU | 制造商:SIPEX 制造商全稱(chēng):Sipex Corporation 功能描述:Low Voltage Electroluminescent Lamp Driver |
| SP4403UEB | 制造商:SIPEX 制造商全稱(chēng):Sipex Corporation 功能描述:Low Voltage Electroluminescent Lamp Driver |
| SP4405 | 制造商:SIPEX 制造商全稱(chēng):Sipex Corporation 功能描述:Low Voltage Electroluminescent Lamp Driver with Regulated Output Voltage |
| SP4405EN | 制造商:SIPEX 制造商全稱(chēng):Sipex Corporation 功能描述:Low Voltage Electroluminescent Lamp Driver with Regulated Output Voltage |
| SP4405EU | 制造商:SIPEX 制造商全稱(chēng):Sipex Corporation 功能描述:Low Voltage Electroluminescent Lamp Driver with Regulated Output Voltage |
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