SP4424
®
Electroluminescent Lamp Driver
Dual Oscillators
■ DC to AC Inverter for EL Backlit
Display Panels
■ 2.2V - 5.0V Battery Operation
■ Dual Oscillator Operation for
Application Flexibility
■ Low Current Standby Mode
APPLICATIONS
■ PDAs
■ Cellular Phones
■ Remote Controls
■ Hand Held Computers
DESCRIPTION
The SP4424 is a high voltage output DC-AC converter that can operate from a single battery
supply voltage as low as 2.2V. The SP4424 is capable of supplying up to 220 VPP signals,
making it ideal for driving electroluminescent lamps. The device features 5µA (maximum)
standby current, for use in low power portable products. An inductor is used to generate high
voltage pulses, and two external capacitors are used to select the inductor and the lamp
oscillator frequencies. The SP4424 is offered in both an 8-pin narrow SOIC and 8-pin micro
SOIC packages. For delivery in die form, please consult the factory.
CCOIL
1
VSS
2
COIL
EL1
8
CLAMP
7
HON
3
6
VDD
4
5
EL2
SP4424
SP4424 Block Diagram
SP4424DS/16
SP4424 Electroluminescent Lamp Driver
1
© Copyright 2000 Sipex Corporation
Power Dissipation Per Package
8-pin NSOIC (derate 6.14mWoC above +70oC)..................500mW
8-pin µSOIC (derate 4.85mWoC above +70oC)...................390mW
ABSOLUTE MAXIMUM RATINGS
These are stress ratings only and functional operation of the device at
these ratings or any other above those indicated in the operation sections
of the specifications below is not implied. Exposure to absolute maximum
rating conditions for extended periods of time may affect reliability.
The information furnished herein by Sipex has been carefully reviewed
for accuracy and reliability. Its application or use, however, is solely the
responsibility of the user. No responsibility for the use of this information
is assumed by Sipex, and this information shall not explicitly or implicitly
become part of the terms and conditions of any subsequent sales
agreement with Sipex. Specifications are subject to change without
prior notice. By the sale or transfer of this information, Sipex assumes
no responsibility for any infringement of patents or other rights of third
parties which may result from its use. No license or other proprietary
rights are granted by implication or otherwise under any patent or
patent rights of Sipex Corporation.
VDD.....................................................................................................7.0
V Input Voltages/Currents
HON (pin1)...............................................................-0.5V to (VDD+0.5V)
COIL (pin3)....................................................................................60mA
Lamp Outputs............................................................................230VPP
Storage Temperature...................................................-65˚C to +150˚C
SPECIFICATIONS
(T= 25°C; VDD =3.0V; Lamp Load = 55nF; Coil = 5mH at 18 Ohms; Coil OSC = 220pF, Lamp OSC = 1500pF unless otherwise noted)
PARAMETER
Supply Voltage, VDD
MIN.
TYP.
MAX.
UNITS
2.2
3.0
5.0
V
35
50
mA
VDD
.
5.0.
V
-0.25
VDD-0.25
0
VDD
0.25V
VDD+0.25
V
10
µA
internal pulldown, VHON=VDD=3V
1
5
µA
VHON=0V
4
6
kHz
Supply Current, ICOIL+IDD
Coil Voltage, VCOIL
HON Input Voltage, VHON
LOW: EL off
HIGH: EL on
HON Current, EL on
Shutdown Current, ISD=ICOIL+IDD
CONDITIONS
VHON=3V
INDUCTOR DRIVE
3
Coil Frequency, fCOIL
Coil Duty Cycle
75
%
Peak Coil Current, IPK-COIL
60
mA
Guaranteed by design.
250
400
Hz
TAMB=+25OC
TAMB=-40OC to +85OC
VPP
TAMB=+25OC, VDD=2.2V
TAMB=+25OC, VDD=3.0V
TAMB=-40OC to +85OC, VDD=3.0V
TAMB=+25OC, VDD=5.0V
EL LAMP OUTPUT
EL Lamp Frequency, fLAMP
150
100
200
Peak to Peak Output Voltage
60
100
60
120
90
130
160
This data sheet specifies environmental parameters, final test conditions and limits as well suggested operating conditions.
For applications which require performance beyond the specified conditions and or limits please consult the factory.
Bonding Diagram:
HON
VDD
SP4424
CLAMP
EL 2
CCOIL
EL1
SP4424DS/16
X
Y
EL1
586.0
187.0
EL2
586.0
-143.0
COIL
VSS
586.0
-376.0
-80.0
-417.0
HON
-562.5
397.0
CAP2
-565.0
-118.0
CAP1
VDD
-562.5
588.0
114.5
417.0
NOTES:
1. Dimensions are in Microns unless otherwise noted.
2. Bonding pads are 125x125 typical.
3. Outside dimensions are maximum, including scribe area.
4. Die thickness is 10 mils +/- 1.
5. Pad center coordinates are relative to die center.
6. Die size 1498 x 1168 ( 59 x 46 mils).
663A
VSS
PAD
Coil
SP4424 Electroluminescent Lamp Driver
2
© Copyright 2000 Sipex Corporation
THEORY OF OPERATION
PIN DESCRIPTION
SP4424CN
1
2
3
4
The SP4424 is made up of four basic circuit
elements: two precision oscillators, a coil, and the
EL driver IC. The oscillators set the coil and lamp
frequencies independently. This allows for the
selective setting of the coil / lamp frequency ratio.
The coil frequency can be selected for maximum
energy transfer per cycle for a given coil value.
The coil oscillator is designed to operate at 75%
duty cycle and the lamp oscillator is designed for
50% DC, for minimum DC offset across the EL
lamp.
8
7
6
5
Pin 1 – CCOIL- Connect Capacitor from VSS to
pin 1 to set coil frequency.
Pin 2 – VSS- Power supply common, connect to
ground.
An external capacitor connected between pin 8
and VSS allows the user to vary the lamp oscillator
frequency from approximately 75Hz (4700 pf) to
350Hz (450 pf). Likewise, an external capacitor
connected between pin 1 and VSS allows the user
to vary the coil oscillator frequency from
approximately 5kHz (390 pf) to 50kHz (22 pf).
The graphs on page 7 show the relationship between
oscillators (LOSC and COSC) and their respective
capacitor values.
Pin 3 – Coil- Coil input, connect coil from
VBATTERY to pin 3.
Pin 4 – EL1- Lamp driver output 1, connect to
EL lamp.
Pin 5 – EL2- Lamp driver output 2, connect to
EL lamp.
Pin 6 – VDD- Power supply for driver, connect to
system VDD.
The coil is an external component connected from
VBATTERY to pin 3 of the SP4424. Energy is stored
in the coil according to the equation EL=1/2LI2,
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=(VL/
L)tON, where VL 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 VSAT of the switch) is across the inductor.
The current in the inductor will then ramp up at a
Pin 7 – HON- Enable for driver operation,
high = active; low = inactive.
5mH/18Ω
Pin 8 – CLAMP- connect Capacitor from VSS to
pin 8 to set lamp frequency.
1500pF
220pF
VIN=3V
+
CCOIL
CLAMP
–
VSS
HON
Coil
VDD
EL1
EL2
HON=VDD=ON
HON=0V=OFF
0.1µF Low ESR
Decoupling
Capacitor
EL Lamp
3Ftl
SP4424
1.6 sq.in.
4.5nF
SP4424 Typical Application
SP4424DS/16
SP4424 Electroluminescent Lamp Driver
3
© Copyright 2000 Sipex Corporation
magnetic field is generated in the coil. During
the low part of fCOIL , the ground connection is
switched open, the field collapses and the voltage
generated in the inductor is directed to the high
voltage H-bridge switches. fCOIL will send as many
charge pulses as possible in 1 Lamp Cycle.{Number of
Coil Freq. }
Coil pulses in 1 lamp cycle =} 12 x Lamp
Freq
(see figure 2 on page 6). 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 6).
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: VL=VBATTERY-IRL-VSAT. 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 tON 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 VBATTERY, L,
RL or ton cause the current in the coil to increase
beyond its rated ISAT, excessive heat will be
generated and the power efficiency will decrease
with no additional light output. The majority of the
current goes through the coil and typically less
than 3 mA is required for VDD of the SP4424. VDD
can range from 2.2V to 5V; it is not necessary that
VDD=VBATTERY. For example, an unregulated voltage
source (3.3V) can be directly connected to the coil,
while a regulated voltage source (2.85V) can be
connected to the IC VDD pin.
The H-bridge consists of two SCR structures that
act as high voltage switches. These two switches
control the polarity of the lamp (capacitor) as it is
charged. The SCR switches are controlled by the
fLAMP signal which is the oscillator frequency
divided by 2.
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 number of
voltage steps from ground to 65V (typical) on pins
4 and 5 which are 180 degrees out of phase (see
figure 3 on page 6). A differential view of the
outputs is shown in figure 4 on page 6.
Coil performance is also a function of the core
material and wire used -- performance variances
may be noticeable from different coil suppliers.
The Sipex SP4424 is tested using a 5mH/18Ω coil
from Hitachi Metals. For suggested coil sources
see page 9.
5mH/18Ω
The fCOIL signal controls a switch that connects
the end of the coil at pin 3 to ground or to open
circuit. The fCOIL signal is a 75% duty cycle signal.
During the time when the fCOIL signal is high, the
coil is connected from VBATTERY to ground and a
1500pF
220pF
VIN=3V
+
CCOIL
CLAMP
–
VSS
HON
Coil
VDD
EL1
EL2
HON=VDD=ON
HON=0V=OFF
0.1µF Low ESR
Decoupling
Capacitor
100Ω
55nF
SP4424
SP4424 Test Circuit
SP4424DS/16
SP4424 Electroluminescent Lamp Driver
4
© Copyright 2000 Sipex Corporation
Sipex now offers low power single chip driver
circuits specifically designed to drive small to
medium sized electroluminescent panels. All that
is required is one external inductor and capacitor.
CIRCUIT LAYOUT CONSIDERATIONS:
The SP4424 IC incorporates two independent
asynchronous oscillators, one of which supplies
the signal for switching of the coil transistor which
generates the coil charge pulses and the other
supplies the clock signal to switch the high voltage
H-bridge output circuit.
Electroluminescent backlighting is ideal for use
with LCD displays, keypads, or other backlit
readouts. Its primary use is to illuminate displays
in dim to dark conditions for momentary periods
of time. EL lamps typically consume less current
than LEDs or bulbs making them ideal for battery
powered products. Also, EL lamps are able to
evenly light an area without creating "hot spots" in
the display.
It is necessary to keep all high voltage signals
away from these oscillator clock signals as much
as possible as crosstalk between the two signals
can cause distortion in the EL drive signal which
can result in either low light output or blinking of
the EL lamp. It is always recommended that a low
ESR decoupling capacitor (0.1 µF or >) be used
between the VDD (pin 6) and ground (pin 2). The
VSS (gnd) pin should in turn be connected to the
system ground plane. If it is connected via a
circuit trace, this trace should be as short and as
wide as possible.
The amount of light emitted is a function of the
voltage level applied to the lamp, the frequency at
which it is applied and the lamp size and method of
construction . There are many variables which can
be optimized for specific applications. Sipex
supplies custom characterization data to aid the
designer in selecting the optimum circuit
configuration.
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. 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,
power hungry, expensive and bulky, and would be
difficult to implemented in most hand held
equipment.
SP4424DS/16
SP4424 Electroluminescent Lamp Driver
5
© Copyright 2000 Sipex Corporation
VPEAK=65V (typical)
EL1 output; charge steps per half cycle based on # of coil pulses per half cycle.
Figure 1. EL output voltage in discrete steps at EL1 output
Number of coil pulses in lamp cycle =
coil
lamp freq. (2) ;
70% duty cycle.
Figure 2. Voltage pulses released from the coil to the EL driver circuitry
EL1 Output
-EL2 Output
Figure 3. EL voltage waveforms from the EL1 and EL2 outputs
EL1 Output
VPP=160V
(typical)
-EL2 Output
Differential Representation (EL1-EL2).
Figure 4. EL differential output waveform of the EL1 and EL2 outputs
SP4424DS/16
SP4424 Electroluminescent Lamp Driver
6
© Copyright 2000 Sipex Corporation
The following performance curves are intended to give the designer a relative scale from which to optimize
specific applications. Absolute measurements may vary depending upon the brand of components chosen.
240
230
15.0
EOUT PP (VAC)
Frequency (KHz)
20.0
10.0
5.0
68
122
100
75
Coil Osc Cap (pF)
30
5
25
4
3
2
7.4
13.6
9.4
11.7
Coil Frequency (KHz)
20
15
10
5
1
0
50
68
100
75
Coil Cap (pF)
122
Coil Cap vs. Light Output
50
68
122
100
75
Coil Osc Cap (pF)
ITOTAL vs. Coil Osc Cap
16
14
12
10
8
6
4
2
600
500
Frequency (Hz)
Light Output (FtL)
190
6
0
0
400
300
200
100
0
1
1.5
2
2.3
Lamp Size (Sq. in)
3
3.4
Lamp Size vs. Light Output
580
680
1400
1000
820
Lamp Osc Cap (pF)
1800
Lamp Frequency vs. Lamp Osc Cap Value
240
250
230
200
EOUT PP (VAC)
EOUT PP (VAC)
200
Coil Frequency vs. EOUT PP
ITOTAL (mAz)
Light Output (FtL)
Coil Frequency vs. Coil Osc Cap Value
210
180
16.0
0.0
50
220
220
210
200
190
180
150
100
50
0
580
680
1400
820
1000
Lamp Osc Cap (nF)
Lamp Osc Cap vs. EOUT PP
SP4424DS/16
1
1800
1.5
2.3
2
Lamp Size (sq. in)
3
3.4
Lamp Size vs. EOUT PP
SP4424 Electroluminescent Lamp Driver
7
© Copyright 2000 Sipex Corporation
The following performance curves are intended to give the designer a relative scale from which to optimize
specific applications. Absolute measurements may vary depending upon the brand of components chosen.
Lamp Frequency (Hz)
Peak to Peak
Voltage (Volts)
140
120
100
80
60
3.0V
2.2V
40
20
0
-40
0
Coil Frequency (Khz)
Total Current (mA)
50
0
0
70
25
Temperature ( o C)
85
8
7
6
5
4
3
2
1
0
3.0V
2.2V
-40
85
Total Current vs. Temperature
CCOIL=220pF; CLAMP=1500pF; Load=55nF
SP4424DS/16
3.0V
2.2V
-40
3.0V
2.2V
70
25
Temperature ( o C)
150
100
Lamp Frequency vs. Temperature
CCOIL=220pF; CLAMP=1500pF; Load=55nF
40
35
30
25
20
15
10
5
0
0
250
200
85
70
25
Temperature ( o C)
Peak to Peak Voltage vs. Temperature
CCOIL=220pF; CLAMP=1500pF; Load=55nF
-40
350
300
0
70
25
Temperature ( o C)
85
Coil Frequency vs. Temperature
CCOIL=220pF; CLAMP=1500pF; Load=55nF
SP4424 Electroluminescent Lamp Driver
8
© Copyright 2000 Sipex Corporation
The coil part numbers presented in this data sheet have been qualified as being suitable for the SP4422A product.
Contact Sipex for applications assistance in choosing coil values not listed in this data sheet.
CTC Coils LTD Hong Kong
Ph: 85-2695-4889
Fax: 85-2695-1842
25 ± 2.0
Mark Technologies:
North American Stocking
distributor for Sankyo and CTC
Ph: 905-891-0165
Fax: 905-891-8534
2.5
6.5 Max
(All dimensions in mm)
9.0 Max
Model Numbers: CH5070AS-203K-006 (20mH, 65Ω)
Sipex Number: S51208-M-1021-Sipex
HITACHI METALS Ltd. Japan
Ph: 3-3284-4936
Fax: 3-3287-1945
HITACHI METALS Hong Kong
Ph: 852-2724-4183
Fax: 852-2311-2093
HITACHI METALS Singapore
Ph: 65-222-3077
Fax: 65-222-5232
HITACHI METALS Chicago, IL
Ph: 847-364-7200
Fax: 847-364-7279
6.8
±0.3
7.0 ±0.5
3.3
±0.3
Part Numbers:
MD735L902B (9mH + 20% 41Ω)
MD735L502A (5mH + 20% 19.8Ω)
(All Dimensions in mm)
Toko Inc. Singapore
Ph: 255-4000
Fax: 250-8134
Toko Korea
Ph: 0551-50-5500
Fax: 0551-93-1110
Toko America Inc. USA
Ph: 847-297-0070
Fax: 847-699-7864
Toko Germany
Ph: 49-7156-96-060
Fax: 49-7156-96-06-26
Toko France
Ph: 01-4557-4465
Fax: 01-4554-2837
4.4 Max
2.75 Max
4.4
(All Dimensions in mm)
Part Numbers:
Toko U.K.
667MA-472N (4.7mH, 13Ω) Ph: 1753-854057-9
Fax: 1753-8503-23
Toko Hong Kong
Ph: 2342-8131
Fax: 2341-9570
muRata USA
Ph: 770-436-1300
Fax: 770-436-3030
muRata Taiwan
Ph: 88-6429-1415-1
Fax: 88-6442-5292-9
muRata Hong Kong
Ph: 85-2237-6389-8
Fax: 85-2237-5556-55
muRata Europe
Ph: 49-9116-6870
Fax: 49-1166-8722-5
muRata Singapore
Ph: 65-758-4233
Fax: 65-753-6181
Part Numbers:
LQN6C472M04 (4.7mH, 35Ω)
LQN6C103M04 (10mH, 80Ω)
Coilcraft USA
Ph: 847-639-6400
Fax: 847-639-1469
Coilcraft Taiwan
Ph: 886-2-264-3646
Fax: 886-2-270-0294
Coilcraft Hong Kong
Ph: 852-770-9428
Fax: 852-770-0729
Coilcraft Europe
Ph: 44-01236-730595
Fax: 44-01236-730627
Coilcraft Singapore
Ph: 65-296-6933
Fax: 465-296-4463 #382
5.0 ±0.3
5.0 ±0.3
4.7 ±0.3
Toko Inc. Japan
Ph: 03-3727-1161
Fax: 03-3727-1176
5.7 ±0.3
(All Dimensions in mm)
.260
6,60 MAX
.175
MAX
4,45
.115
2,92 MAX
Magnetically Shielded
Part Numbers:
DS1608C-106 (10mH, 32Ω)
SP4424DS/16
6.0 ±0.3
(All Dimensions in mm)
SP4424 Electroluminescent Lamp Driver
9
© Copyright 2000 Sipex Corporation
EL polarizers/transflector
manufacturers
Nitto Denko
San Jose, CA
Phone: (510) 445-5400
Astra Products
Baldwin, NJ
Phone: (516) 223-7500
Fax: (516) 868-2371
EL Lamp manufacturers
Metro Mark/Leading Edge
Minnetonka, MN
Phone: (800) 680-5556
Phone: (612) 912-1700
Midori Mark Ltd.
1-5 Komagata 2-Chome
Taita-Ku 111-0043 Japan
Phone: 81-03-3848-2011
Luminescent Systems Inc. (LSI)
Lebanon, NH
Phone: (603) 643-7766
Fax: (603) 643-5947
SP4424DS/16
SP4424 Electroluminescent Lamp Driver
10
NEC Corporation
Tokyo, Japan
Phone: (03) 3798-9572
Fax: (03) 3798-6134
Seiko Precision
Tokyo, Japan
Phone: (03) 5610-7089
Fax: .) 5610-7177
Gunze Electronics
2113 Wells Branch Parkway
Austin, TX 78728
Phone: (512) 752-1299
Fax: (512) 252-1181
© Copyright 2000 Sipex Corporation
All package dimensions in inches
8-pin µSOIC
8-pin NSOIC
0.0256
BSC
12.0˚
±4˚
0.012
±0.003
0.189/0.197
0.150/0.157
SP4424CN
0.228/0.244
0.0965
±0.003
0.053/0.069
R .003
0.118
±0.002
SP4424CU
0.014/0.019
0.050 BSC
1
0.008
0.16
±0.003
12.0˚
±4˚
0.01
0.020
0.020
1
3.0˚
±3˚
0.0215
±0.006
0.037
Ref
2
0.116
±0.004
0.034
±0.002
0.116
±0.004
0.040
±0.002
0.013
±0.005
0.118
±0.002
95 SP4424CN per tube, no minimum quantity
0˚ - 6˚
0.006
±0.006
0.006
±0.006
0.118
±0.004
0.004
±0.002
50 SP4424CU per tube
P
W
NSOIC-8 13" reels: P=8mm, W=12mm
µSOIC-8 13" reels: P=8mm, W=12mm
Pkg.
CN
CU
SP4424DS/16
Minimum qty per reel
Standard qty per reel
Maximum qty per reel
500
500
2500
2500
3000
3000
SP4424 Electroluminescent Lamp Driver
11
© Copyright 2000 Sipex Corporation
ORDERING INFORMATION
Model
Operating Temperature Range
Package Type
SP4424CN . ............................................ -40˚C to +85˚C ......................................... 8-Pin NSOIC
SP4424CU . ............................................ -40˚C to +85˚C ......................................... 8-Pin µSOIC
SP4424CX .............................................. -40˚C to +85˚C ........................................................ Die
SP4424NEB ..................................................... N/A ............................... NSOIC Evaluation Board
SP4424UEB ..................................................... N/A ............................... µSOIC Evaluation Board
Please consult the factory for pricing and availability on a Tape-On-Reel option.
Corporation
SIGNAL PROCESSING EXCELLENCE
Sipex Corporation
Headquarters and
Sales Office
22 Linnell Circle
Billerica, MA 01821
TEL: (978) 667-8700
FAX: (978) 670-9001
e-mail: [email protected]
Sales Office
233 South Hillview Drive
Milpitas, CA 95035
TEL: (408) 934-7500
FAX: (408) 935-7600
Sipex Corporation reserves the right to make changes to any products described herein. Sipex does not assume any liability arising out of the
application or use of any product or circuit described hereing; neither does it convey any license under its patent rights nor the rights of others.
SP4424DS/16
SP4424 Electroluminescent Lamp Driver
12
© Copyright 2000 Sipex Corporation