- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄373829 > ZSP4422ANEB (Electronic Theatre Controls, Inc.) Electroluminescent Lamp Driver PDF資料下載
參數(shù)資料
| 型號： | ZSP4422ANEB |
| 廠商： | Electronic Theatre Controls, Inc. |
| 英文描述： | Electroluminescent Lamp Driver |
| 中文描述： | 電致發(fā)光燈驅(qū)動器 |
| 文件頁數(shù)： | 4/8頁 |
| 文件大小： | 154K |
| 代理商： | ZSP4422ANEB |
Zywyn Corporation
ZSP4422A
4
March 2004
rev. 01
Zywyn
Circuit Description
The ZSP4422A is made up of three basic circuit elements,
an oscillator, coil,and switched H-bridge network. The
oscillator provides the device with an on-chip clock source
used to control the charge and discharge phases for the
coil and lamp. An external capacitor connected between
pins 7 and 8 allows the user to vary the oscillator frequency
from 32kHz to 400kHz. In general, increasing the C
OSC
capacitor will increase the lamp output.
The suggested oscillator frequency is 90kHz (C
OSC
=100pF). The oscillator output is internally divided to
create two internal control signals, f
COIL
and f
LAMP
. The
oscillator output is internally divided down by 8 flip-flops,
a 90kHz signal will be divided into 8 frequencies; 45kHz,
22.5kHz, 11.2kHz, 5.6kHz, 2.8kHz, 1.4kHz, 703Hz, and
352Hz. The third flip-flop output (8kHz) is used to drive the
coil (see
Figure 1
) and the eighth flip-flop output (250Hz)
is used to drive the lamp. Although the oscillator fre-
quency can be varied to optimize the lamp output, the
ratio of f
COIL
/f
LAMP
will always equal 32.
The on-chip oscillator of the ZSP4422A can be overdriven
with an external clock source by removing the C
OSC
capacitor and connecting a clock source to pin 8. The
clock should have a 50% duty cycle and range from
V
DD
to ground. An external clock signal may be desirable
in order to synchronize any parasitic switching noise with
the system clock. The maximum external clock frequency
that can be supplied is 400kHz.
The coil is an external component connected from
V
BATTERY
to pin 3 of the ZSP4422A. Energy is stored in the
coil according to the equation E
L
=1/2LI
2
, where I is the
peak current flowing in the inductor. The current in the
inductor is time dependent and is set by the “ON” time of
the coil switch: I = (V
L
/L)t
ON
, where V
L
is the voltage
across the inductor. At the moment the switch closes, the
current in the inductor is zero and the entire supply voltage
(minus the V
SAT
of the switch) is across the inductor. The
current in the inductor will then ramp up at a 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
L
= V
BATTERY
– IR
L
–
V
SAT
. 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
ON
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
BATTERY
, L, RL or t
ON
cause the current in the coil to
increase beyond its rated I
SAT
, excessive heat will be
generated and the power efficiency will decrease with no
additional light output. The Zywyn ZSP4422A is final
tested using a 5mH/18
coil from Hitachi Metals. For
suggested coil sources see,
“Coil Manfacturers.”
The supply V
DD
can range from +2.2V to +5.0V. It is not
necessary that V
DD
= V
BATTERY
. V
BATTERY
should not
exceed max coil current specification. The majority of the
current goes through the coil and is typically much greater
than I
DD
.
The f
COIL
signal controls a switch that connects the end of
the coil at pin 3 to ground or to open circuit. The f
COIL
signal is a 94% duty cycle signal switching at 1/8 the
oscillator frequency. For a 64kHz oscillator f
COIL
is 8kHz.
During the time when the f
COIL
signal is high, the coil is
connected from V
BATTERY
to ground and a charged mag-
netic field is created in the coil. During the low part of f
COIL
,
the ground connection is switched open, the field col-
lapses and the energy in the inductor is forced to flow
toward the high voltage H-bridge switches. f
COIL
will send
16 of these charge pulses (see
Figure 5)
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 4
).
The H-bridge consists of two proprietary low on-resis-
tance high-voltage switches. These two switches control
the polarity of how the lamp is charged. The high-voltage
switches are controlled by the f
LAMP
signal which is the
oscillator frequency divided by 256. For a 64kHz oscillator,
f
LAMP
= 256Hz. The direction of current flow is determined
by which high-voltage switch is enabled. One full cycle of
the H-bridge will create 16 voltage steps from ground to
80V (typical) on pins 4 and 5 which are 180 degrees out of
phase from each other (see
Figure 6
). A differential repre-
sentation of the outputs is shown in
Figure 7
.
Layout Considerations
The ZSP4422A circuit board layout must observe careful
analog precautions. For applications with noisy voltage
power supplies a 0.1μF low ESR decoupling capacitor
must be connected from V
DD
to ground. Any high voltage
traces should be isolated from any digital clock traces or
enable lines. A solid ground plane connection is strongly
recommended. All traces to the coil or to the high voltage
outputs should be kept as short as possible to minimize
capacitive coupling to digital clock lines and to reduce EMI
emissions.
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 trans-
former, transistors, and several resistors and capacitors.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| ZSP4422AUEB | Electroluminescent Lamp Driver |
| ZSR520 | 2.85 TO 12 VOLT FIXED POSITIVE LOCAL VOLTAGE REGULATOR |
| ZSR1000 | Circular Connector; Body Material:Aluminum; Series:PT00; Number of Contacts:61; Connector Shell Size:24; Connecting Termination:Crimp; Circular Shell Style:Wall Mount Receptacle; Circular Contact Gender:Pin; Insert Arrangement:24-61 |
| ZSR1000C | Circular Connector; Body Material:Aluminum; Series:PT00; Number of Contacts:3; Connector Shell Size:8; Connecting Termination:Crimp; Circular Shell Style:Wall Mount Receptacle; Circular Contact Gender:Pin; Insert Arrangement:8-33 |
| ZSR1000G | Circular Connector; Body Material:Aluminum; Series:PT00; No. of Contacts:3; Connector Shell Size:8; Connecting Termination:Crimp; Circular Shell Style:Wall Mount Receptacle; Circular Contact Gender:Socket; Insert Arrangement:8-33 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ZSP4422AUEB | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Electroluminescent Lamp Driver |
| ZSP4423LCU/TR | 制造商:ZYWYN 功能描述:ZSP4423 Series 2.2 to 5 V Surface Mount Electroluminescent Lamp Driver - MSOP-8 |
| ZSP4491LEU | 制造商:ZYWYN 功能描述:ZSP4491 Series 44 kHz Two Panel Electroluminescent Lamp Driver-MSOP-10 |
| ZSP500 | 制造商:LSI 制造商全稱:LSI 功能描述:Highly Efficient Quad-MAC DSP Core |
| ZSP540 | 制造商:LSI 制造商全稱:LSI 功能描述:Highly Efficient Quad-MAC DSP Core |
發(fā)布緊急采購，3分鐘左右您將得到回復。