Datasheet SP4428CN, SP4428NEB Datasheet (Sipex Corporation)

®

SP4428

Electroluminescent Lamp Driver

High Drive Capability for Lo w Voltage Applications

■ Low Power +1.1V to +1.7V Single
Cell Operation

■ Low-Cost EL Driver Ideal for Backlighting

■ DC-to-AC Inverter Generates High

Voltage AC to Drive EL Lamps

■ Externally Adjustable Oscillator

■ Low Current Standby Mode

APPLICATIONS

■ Pagers

■ Watches

■ Backlit LCD Displays

DESCRIPTION

The SP4428 is a high voltage output DC-AC converter that can operate from a single 1.5 VDC
power supply. The SP4428 is capable of supplying 200 VPP (typical), making it ideal for driving
electroluminescent lamps. The device features 1µA (typical) standby current, for use in low
power portable products. One external inductor is required to generate the high voltage
charge, and one external capacitor is used to produce a clock signal that generates the coil
and lamp frequencies. The SP4428 is ideal for PDAs, pagers, and other low power portable
applications using LCDs in dim or low light environments. The SP4428 is offered in an 8-pin
narrow SOIC. For delivery in die form, please consult the factory.

C

OSC

V

SS

COIL

D1

Block Diagram

SP4428DS/16 SP4428 Electroluminescent Lamp Driver © Copyright 2000 Sipex Corporation

1
2

3
4

SP4428

1

8
7

6

5

HON
V

DD

EL1

EL2

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.

TA= +25˚C unless otherwise noted

VDD............................................................................................................5V

Input Voltages/Currents

Lamp Outputs.............................................................................230V

Storage Temperature....................................................-65˚C to +150˚C

Power Dissipation Per Package

8-pin NSOIC (derate 6.14mW/oC above +70oC).................................500mW

HON (pin1).........................................-0.5V to (VDD+0.5V)

COIL (pin3)............................................................100mA

PP

SPECIFICATIONS

(T= 25°C; VDD = 1.5V; Lamp Capacitance = 4.7nF; Coil = 470µH at 4.9 Ohms; C

RETEMARAP.NIM.PYT.XAMSTINUSNOITIDNOC

V,egatloVylppuS

DD

I+

,tnerruCylppuSI

LIOC

DD

V,egatloVlioC

LIOC

V,egatloVtupnINOH

NOH

ffoLE:WOL

noLE:HGIH

noLE,tnerruCNOH351

I=

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DS

LIOC

DD

EVIRDROTCUDNI

f,ycneuqerFlioC

LIOC

elcyCytuDlioC09%

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TUPTUOPMALLE

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egatloVtuptuOkaePotkaeP09

1.15.17.1V
53

54

V

DD

0

52.0-

52.0-

V

DD

V

V

DD

5.001

8.82zHk

051
003

054

051

021

021

061

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.

= 180pF unless otherwise noted) C

OSC

05
08

7.1

V52.0

52.0+

DD

V

DD

Am

V

DD

V

V

µA
µA

V

NOH

INT

V,V1.1=

NOH

V,V5.1=

NOH

V0=

= 1800pF

V1.1=
V5.1=

V=

V,nwodlluplanretni

NOH

V5.1=

DD

001Am.ngisedybdeetnarauG

005
055

zH

057

V

PP

O

T

52+=

V,C

BMA

O

T

52+=

BMA

O

04-=

T

BMA

V

V1.1=

DD

V

V5.1=

DD

V1.1=

DD

V,C

V5.1=

DD

O

58+otC

V,C

V5.1=

DD

SP4428DS/16 SP4428 Electroluminescent Lamp Driver © Copyright 2000 Sipex Corporation

2

PIN DESCRIPTION

1
2
3
4

SP4428

8
7
6
5

THEORY OF OPERATION

The SP4428 is made up of three basic circuit
elements, an oscillator, coil, driver 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 1 and VSS allows the user to vary the oscillator
frequency. For a given choice of coil inductance
there will be an optimum C
gives the maximum light output in a given lamp.

Capacitor value that

OSC

Pin 1 – C
set Oscillator frequency.

- Connect CAP from VSS to Pin 1 to

OSC

Pin 2 – VSS- Power supply common, connect to
ground.

Pin 3 – Coil- Coil input, connect coil from
V

BATTERY

to Pin 3.
Pin 4 – D1- Diode cathode connection.
Pin 5 – EL2- Lamp driver output1, connect to

EL lamp.
Pin 6 – EL1- Lamp driver output2, connect to

EL lamp.
Pin 7 – VDD- Power supply for driver, connect to

system VDD.
Pin 8 – HON- Enable for driver operation,

high = active; low = inactive.

V

DD

.1µF

180pF

7

V

DD

OSC

C

1

OSC

Cap1

FF1 FF6

1MΩ

V

SS

2

8

HON

Q

Q

The suggested oscillator frequency is 28.8kHz
(C

=180pF). The oscillator output is internally

OSC

divided to create the control signal f
The oscillator output is internally divided down

LAMP

by 6 flip flops, a 28.8kHz signal will be divided
into 6 frequency levels; 14.4kHz, 7.2kHz, 3.6kHz,

1.8kHz, 900Hz, and 450Hz. The oscillator output
(28.8kHz) is used to drive the coil (see figure 2 on
page 7) and the sixth flip flop output (300Hz) is
used to drive the lamp. Although the oscillator
frequency can be varied to optimize the lamp
output, the ratio of f

COIL/fLAMP

will always equal 64.

The coil is an external component connected from
V
developed in the coil according to the equation

to pin 3 of the SP4428. Energy is

BATTERY

EL=1/2LI2 where the current I is defined as

f

f

COIL

LAMP

f

LAMP

I=(V

V

BATTERY

3

Coil

-IR-VOL)/RT. In order to maximize the

BATTERY

470µH/4.9Ω

IN4148

SCR1

EL1 EL2

5

Optional
1,800pF

4

D1

SCR2

6

.

EL Lamp

SP4428 Schematic

SP4428DS/16 SP4428 Electroluminescent Lamp Driver © Copyright 2000 Sipex Corporation

3

energy produced by the coil V
represent the largest voltage in the system (up to

BATTERY

should

the maximum tolerance of the coil) and the coil
should have low resistance; V
with a 470µH/4.9Ω coil are typical. The majority

BATTERY

= 1.5 VDC

of the current goes through the coil and typically
less than 1mA is required for VDD of the SP4428.
VDD can range from 1.5V to 1.7V; it is not necessary
that VDD=V
core material and winding used -- performance

. Coils are also a function of the

BATTERY

variances may be noticeable from different coil
suppliers. The Sipex SP4428 is final tested using
a 470µH/4.9Ω coil from Sumida. For suggested
coil sources see page 9.

The f
end of the coil at pin 3 to ground or to open circuit.
The f
at the oscillator frequency. During the time when
the f
V
created in the coil. During the low part of f
ground connection is switched open, the field

signal controls a switch that connects the

COIL

signal is a 90% duty cycle signal switching

COIL

signal is high, the coil is connected from

COIL

to ground and a charged magnetic field is

BATTERY

COIL

, the

collapses and the energy in the inductor is forced
to flow toward the lamp. f
charge pulses every half cycle (see figure 2

will send 32 of these

COIL

on page 7) 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 1 on page 7).

The H-bridge consists of two SCR structures that
act as high voltage switches. These two switches
control the polarity of how the lamp is charged.
The SCR switches are controlled by the f
signal which is the oscillator frequency divided by

64. For a 20kHz oscillator, f

LAMP

=300Hz.

LAMP

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 voltage step
from ground to 80V (typical) on pins 5 and 6 which
are 180 degrees out of phase with each other
(see figure 3 on page 7). A differential view of the
outputs is shown in figure 4 on page 7. If Line
Noise is of concern it is advisable to add a
decoupling cap at VDD.

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 transformer, transistors,
and several resistors and capacitors. 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 if all that is required is
one external inductor fast recovery diode and two
capacitors.

Pager
Application

1.5 Volt
Battery

+

-

0.1µF
180pF

Coil

470µH

4.9 Ohms

Fast
Recovery
Diode

1

HON

C

OSC

V

SS

Coil
D1

Optional
1800pF CAP

V
EL1
EL2

DD

5 FtL

LAMP

1.5 SQ. IN.

Typical SP4428 Application Circuit

SP4428DS/16 SP4428 Electroluminescent Lamp Driver © Copyright 2000 Sipex Corporation

4

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 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.

The amount of light emitted is a function of the
voltage applied to the lamp, the frequency at which
it is applied, the lamp material used and its
size. There are many variables which can be
optimized for specific applications. Sipex supplies
characterization charts to aid the designer in
selecting the optimum circuit configuration
(see page 6 and 7).

SP4428DS/16 SP4428 Electroluminescent Lamp Driver © Copyright 2000 Sipex Corporation

5

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.

VDD=V

(mA)

DD

Total I

Frequency (Hz)

=1.5V; coil = 470µH/4ohm; C

COIL

Total IDD vs. Temperature

70
60
50
40
30
20
10

0

-40 0 25 70 85

Temperature (

O

Lamp Frequency vs. Temperature

500
450
400
350
300
250
200
150
100

50

0

-400 257085

Temperature (OC)

= 180pf; C

OSC

= 1800pf; C

INT

LOAD

= 4.7nF

Peak voltage vs. Temperature

= 1.5V

V

200

DD

150
100

50

Peak-to-Peak

voltage (Volts)

0

-40 0 25 70 85

C)

Temperature (OC)

SP4428DS/16 SP4428 Electroluminescent Lamp Driver © Copyright 2000 Sipex Corporation

6

V

=80V (typical)

PEAK

EL1 output; 32 charge steps per half cycle

Figure 1. EL output voltage in discrete steps at EL1 output

16 coil pulses per half cycle; 94% 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

Differential representation EL

EL1 Output

-EL2 Output

.

12

VPP=160V
(typical)

Figure 4. EL differential output waveform of the EL1 and EL2 outputs

SP4428DS/16 SP4428 Electroluminescent Lamp Driver © Copyright 2000 Sipex Corporation

7

C

OSC

BONDING DIAGRAM

HON

V

V

DD

SS

X

Y

EL1

EL2
CAP

COIL

DAPNIPX Y

NOH8 5.228-5.393

V

V

C

70.5025.814

DD

1LE6 0.6975.943
2LE5 5.0785.91
PAC4 5.0785.981-

LIOC3 5.5875.983-

25.5715.024-

SS

10.848-0.601-

CSO

NOTES:

1. Dimensions are in Microns unless otherwise noted.

2. Bonding pads are 125 X 125 typical.

3. Outside dimensions are maximum, including scribe area.

4. Die thickness is 380 ± 25 microns.

5. Pad center coordinates are relative to die center .

6. Die size (step size): 81 X 46 mils

Figure 5. Bonding Diagram

SP4428DS/16 SP4428 Electroluminescent Lamp Driver © Copyright 2000 Sipex Corporation

8

Coil Manufacturers New Coils

Coilcraft USA

Ph: [phone]
Fax: [phone]

Coilcraft Europe

Ph: 44 01236 730595
Fax: [phone]

Coilcraft Taiwan

Ph: 886/2/264-3646
Fax: [phone]

Coil Craft Singapore

Ph: 65 296-6933
Fax: [phone] #382

Coilcraft Hong Kong

Ph: 852 770-9428
Fax: [phone]

Part No. DO1608C-474
470µH, 3.60 ohm

.260

6.60

.175

Max

(All Dimensions in mm)

Max

.155

Dia

.115

Max

muRata USA

Ph: [phone]
Fax: [phone]

muRata Europe

Ph: 011-4991166870
Fax: [phone]

KOA Speer Electr onics, Inc.

Ph: 814-362-5536
Fax: [phone]

Part No. LPC4045TE471K
470µH, 4.55 ohm

Sumida Electric Co., LTD.
USA

Ph: [phone]
Fax: [phone]

Sumida Electric Co., LTD.
Japan

Ph: 03-3607-5111
Fax: [phone]

Toko America Inc. USA

Ph: [phone]
Fax: [phone]

Toko Inc. Europe

Ph: [phone]
Fax: [phone]

muRata T aiwan Electronics

Ph: 011 88642914151
Fax: [phone]

muRata Electronics
Singapore

Ph: 011 657584233
Fax: [phone]

Sumida Electric Co., LTD.
Singapore

Ph: 2963388
Fax: [phone]

Sumida Electric Co., LTD.
Hong Kong

Ph: 28806688
Fax: [phone]

Toko Inc. Japan

Ph: 03 3727 1161
Fax: [phone]

Toko Inc. Singapore

Ph: (255) 4000
Fax: [phone]

muRata Hong Kong

Ph: 011-85223763898
Fax: [phone]

Part No. LQN4N471K04
470µH, 11.5 ohm

Part No. CDRH74-471MC
470µH, 3.01 ohm

Toko Inc. Hong Kong

Ph: 2342-8131
Fax: [phone]

Part No. 667MA471N
470µH, 1.90 ohm

4.4 Max

5.0 ±0.35.0 ±0.3

4.7 ±0.3

5.7 ±0.3

(All Dimensions in mm)

4.0 ± 0.2

4.5 Max

(All Dimensions in mm)

7.3 ±0.2

(All Dimensions in mm)

4.4 Max

4.5 ±

7.3

4.5

Max

2.75 Max

(All Dimensions in mm)

EL polarizers/transflector
manufacturers

Nitto Denko
Yoshi Shinozuka
Bayside Business Park 48500
Fremont, CA 94538
Phone: [phone]
Fax: [phone]

Top Polarizer- NPF F1205DU
Bottom - NPF F4225
or (F4205) P3 w/transflector

Transflector Material
Astra Products
Mark Bogin
P.O. Box 479
Baldwin, NJ 11510
Phone [phone]

EL Lamp manufacturers

Leading Edge Ind. Inc.
11578 Encore Circle
Minnetonka, MN 55343
Phone [phone]

Midori Mark Ltd.
1-5 Komagata 2-Chome
Taita-Ku 111-0043 Japan
Phone: [phone]

Luminescent Systems inc. (LSI)
101 Etna Road
Lebanon, NH. 03766-9004
Phone: [phone]
Fax: [phone]

NEC Corporation
Yumi Saskai
7-1, Shiba 5 Chome, Minato-ku,
Tokyo 108-01, Japan
Phone: [phone]
Fax: [phone]

Seiko Precision
Shuzo Abe
1-1, Taihei 4-Chome,
Sumida-ku, Tokyo, 139 Japan
Phone: [phone]
Fax: [phone]

Gunze Electronics
2113 Wells Branch Parkway
Austin, TX 78728
Phone: [phone]
Fax: [phone]

Fax [phone]

SP4428DS/16 SP4428 Electroluminescent Lamp Driver © Copyright 2000 Sipex Corporation

9

All package dimensions in inches

8-pin NSOIC

0.189/0.197

SP4428

1

0.228/0.2440.150/0.157

0.014/0.019

0.053/0.069

0.050 BSC

95 NSOIC SP4428 per tube, no minimum quantity

P

W

NSOIC-8 13" reels: P=8mm, W=12mm

Pkg. Minimum qty per reel Standard qty per reel Maximum qty per reel

CN 500 2500 3000

SP4428DS/16 SP4428 Electroluminescent Lamp Driver © Copyright 2000 Sipex Corporation

10

ORDERING INFORMATION

Model Temperature Range Package Type

SP4428CN . ............................................. 0˚C to +70˚C ...........................................8-Pin NSOIC

SP4428NEB............................................................................................NSOIC 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: [phone]
FAX: [phone]
e-mail: [e-mail]

Sales Office

233 South Hillview Drive
Milpitas, CA 95035
TEL: [phone]
FAX: [phone]

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 herein; neither does it convey any license under its patent rights nor the rights of others.

SP4428DS/16 SP4428 Electroluminescent Lamp Driver © Copyright 2000 Sipex Corporation

11