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參數(shù)資料
| 型號： | SP4405 |
| 英文描述： | Low Voltage Electroluminescent Lamp Driver with Regulated Output Voltage |
| 中文描述： | 低電壓電致發(fā)光燈驅動器，輸出電壓 |
| 文件頁數(shù)： | 5/20頁 |
| 文件大?。?/td> | 158K |
| 代理商： | SP4405 |
SP4405DS/18
SP4405 Low Voltage Electroluminescent Lamp Driver
5
Copyright 2000 Sipex Corporation
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 can be
difficult to implement in some smaller hand
held equipment.
Sipex
now offers low power
single chip driver circuits specifically
designed to drive small to medium sized
electroluminescent panels.
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
SP4405
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
SP4405
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 48.6kHz (R
= 450k
) for f
.
The oscillator output is internally divided down
by 7 flip flops to create a second internal control
signal at 380Hz for f
LAMP
.
The Coil
The supply V
BATTERY
can range from +2.2V to
+4.5V. V
does 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
SP4405
. Energy is
stored in the coil according to the equation
E
=1/2LI
is the product I
= (t
) (V
- 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 transistor for f
, 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,
Figure 2. Typical Application Circuit for the SP4405, Set
for a Square Wave Output with C
INT
= 0.1
μ
F
R
OSC
V
SS
COIL
C
INT
SP4405
V
BATTERY
C1
0.1
μ
F
OSC
R
L1
470
μ
H
3
6
8
1
7
2
ELEN
1*D1
C
INT
0.1
μ
F
*optional device
V
DD
EL2
EL1
EL Lamp
5
4
C2
1nF
相關PDF資料 |
PDF描述 |
|---|---|
| SP4405EN | Low Voltage Electroluminescent Lamp Driver with Regulated Output Voltage |
| SP4405EU | Low Voltage Electroluminescent Lamp Driver with Regulated Output Voltage |
| SP4405NEB | Low Voltage Electroluminescent Lamp Driver with Regulated Output Voltage |
| SP4412 | Electroluminescent Lamp Driver |
| SP4412A | Electroluminescent Lamp Driver |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| SP4405EN | 制造商:SIPEX 制造商全稱: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:Sipex Corporation 功能描述:Low Voltage Electroluminescent Lamp Driver with Regulated Output Voltage |
| SP4405NEB | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Low Voltage Electroluminescent Lamp Driver with Regulated Output Voltage |
| SP4405UEB | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Low Voltage Electroluminescent Lamp Driver with Regulated Output Voltage |
| SP4412 | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Electroluminescent Lamp Driver |
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