- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄385854 > SP4439 Ultra-Quiet Electroluminescent Lamp Driver with Programmable Wave Shape(超靜場致發(fā)光燈驅(qū)動器（可編程波形）) PDF資料下載
參數(shù)資料
| 型號： | SP4439 |
| 英文描述： | Ultra-Quiet Electroluminescent Lamp Driver with Programmable Wave Shape(超靜場致發(fā)光燈驅(qū)動器（可編程波形）) |
| 中文描述： | 超靜音電致發(fā)光燈帶可編程波形（超靜場致發(fā)光燈驅(qū)動器（可編程波形）驅(qū)動程序） |
| 文件頁數(shù)： | 6/13頁 |
| 文件大?。?/td> | 193K |
| 代理商： | SP4439 |
Rev. 2/16/01 SP4439 Ultra-Quiet Electroluminescent Lamp Driver With Programmable Waveshape Copyright 2001 Sipex Corporation
6
The f
COIL
signal controls a switch that connects
the coil at the COIL pin to ground or to open
circuit. The f
COIL
signal is a 90% duty cycle
signal switching at the oscillator frequency,
32kHz. During the time when the f
COIL
signal is
HIGH, the coil is connected from V
COIL
to ground
and a charged magnetic field is created in the
coil. When the f
COIL
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.
The Switched H-Bridge Network
Current sources and precision controlled timing
of the SP4439
switched H-bridge network are
designed to reduce EMI emissions, extend EL
lamp life, and reduce the overall power dissipation
of the device.
Current sources were added to the high and low
side of the H-bridge network to ensure control of
the charge and discharge of the EL lamp. The
precision MOSFET timing of the SP4439 allows
for controlled charging and discharging of the
EL lamp to minimize EMI and audible noise.
Refer to
Figure 7
for the single ended and
differential output waveforms to the EL lamp.
The Precision Bridge Control Circuitry
This circuitry is driven by the internal oscillator
to control the timing of the charge and discharge
of the EL lamp to eliminate EMI and noise
concerns. This control circuitry drives the H-
bridge timing. Refer to
Figure 2
for the internal
block diagram of the SP4439.
Fine Tuning Performance
Circuit performance of the SP4439
can be
improved with some of the following suggestions:
Increase EL Lamp Light Output
: By
connecting a fast recovery diode from COIL
(pin 5) to C
INT
(pin 6), the internal diode of the
switched H-bridge network is bypassed resulting
in an increase in light output at the EL lamp. We
suggest a fast recovery diode, such as the industry
standard 1N4148, be used for D1. This circuit
connection can be found in
Figures 1 and 2.
By adjusting the values of R
C
and R
D
the rate of
change and discharge can be adjusted. Faster
rise time typically means greater light output and
greater noise. The more gradual the rise and fall
edges are, the less noise is produced by the
lamps. For example a sign wave would not
generate any noise.
Changing the EL Lamp Output Voltage
Waveform
:
Designers can alter the trapezoidal
output voltage waveform to the EL Lamp.
Changing the capacitance of the integrating
capacitor, C
INT
, will ideally integrate the output
waveform making it appear more sinusoidal.
This will minimize any noise inherent to the
application.
Programming the Ultra-Quiet SP4439
Output Voltage Wave-shape:
The optimal
low noise wave-form to drive an EL lamp is a
sinusoid. The drawbacks of using a sine wave to
drive an EL lamp are twofold. First, the luminance
of an EL lamp is proportional to the root mean
square value of the applied voltage. Second, a
high voltage sine wave generator is difficult to
design due to inefficiencies and space constraints.
The first problem can be overcome by using a
square wave to drive the lamp. This is the most
efficient waveform and has the highest RMS
voltage but it creates the highest noise when
applied to an EL lamp. Sipex has found the best
trade off between noise and luminance is a
trapezoid or clipped sinusoid waveform.
The SP4439 output wave-shape is programmable
in terms of its rise and fall times. The output
waveform seen across the lamp terminals is
actually generated as a single ended waveform
and is measured differentially. This is shown in
figure 7.
The single ended waveform can be broken up
into three regions: A charge region, a hold
region and a discharge region. The differential
rise-time actually encompasses both a charge
and a discharge region.
The charge and discharge regions are controlled
independently by two resistors: RC is the charge
resistor and RD is the discharge resistor. The
rise-time (tr) is defined as 800uS for the
differential waveform. Therefore the single ended
charge time is one half that or 400uS. Use the
following to find the full-scale charge time:
t
r
= T
2
-T
1
/
1.25
∴
(1.25) where T
2
- T
1
is the full scale
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| SP6002 | Synchronous Rectifier Driver |
| SP6002S8RG | Synchronous Rectifier Driver |
| SP6002S8TG | Synchronous Rectifier Driver |
| SP6003A | Synchronous Rectifier Driver |
| SP6003AS8RG | Synchronous Rectifier Driver |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SP4446 | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:High Output Voltage Boost Regulator LCD Bias Regulator |
| SP4446_06 | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:High Output Voltage Boost Regulator LCD Bias Regulator |
| SP4446EB | 功能描述:電源管理IC開發(fā)工具 Hi Voltage Boost Reg LCD Bias Regulator RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
| SP4446EK | 制造商:Exar Corporation 功能描述:IC,SMPS CONTROLLER,HIGH OUTPUT VOLTAGE BOOST REGULATOR, LCD BIAS REGULATOR |
| SP4446EK/TR | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:High Output Voltage Boost Regulator LCD Bias Regulator |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。