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SP4427 Electroluminescent Lamp Driver Dual Oscillators with High Drive Capability
s DC to AC Inverter for EL Backlit Display Panels s Low Voltage, Single Battery Operation (vbat > 1.1 Vdc) s Dual Oscillator Operation for Application Flexibility s Low Current Standby Mode
APPLICATIONS
s Pagers s PDA's s Backlit LCD Displays
DESCRIPTION...
The SP4427 is a high voltage output DC-AC converter that can operate from a single 1.5 Vdc battery supply. The SP4427 is capable of supplying up to 250 Vpp signals, making it ideal for driving electroluminescent lamps. The device features 100nA (typ) standby current, for use in low power portable products. One external inductor is required to generate the high voltage charge, and two external capacitors are used to select the oscillator and lamp frequencies. The SP4427 is offered in both an 8 pin narrow SOIC or micro SOIC package. For delivery in die form, please consult the factory.
6 VDD COIL 7 1 HON EN 8 Bit Counter Cosc Coil OSC H Bridge EL1 5
3
Losc 8
Lamp OSC VSS 2
EL2 4
Block Diagram
SP4427DS/01 SP4427 Electroluminescent Lamp Driver (c) Copyright 1997 Sipex Corporation
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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. Vdd............................................................................................................7.0V Input Voltages/Currents HON (pin1)..........................................-0.5V to (Vdd+0.5V) COIL (pin3)............................................................100mA Lamp Outputs.............................................................................250Vpp Storage Temperature....................................................-65C to +150C Power Dissipation.......................................................................200mW
SPECIFICATIONS
(T= 25C; Vdd = 1.5V; Lamp Capacitance = 8000pF; Coil = 20 mH at 70 Ohms; Coil OSC = 220pF, Lamp OSC = 1800pF unless otherwise noted)
PARAMETER INPUT CHARACTERISTICS
MIN.
TYP.
MAX.
UNIT
CONDITIONS
Supply Voltage Total Supply Current Quiescent Supply Current Hon Voltage On Hon Current On Hon Voltage Off INDUCTOR DRIVE Peak Current Pulse Rate Duty Cycle LAMP OUTPUT Differential Voltage Frequency Lamp Capacitance 1.1
1.5 10 100 Vdd
15 200
Volts mA nA Volts A Volts
Vdd= 1.5V 5%; Hon= 1.5V Vdd= 1.5V 5%; Hon= 0.2V
10 Internal pulldown
3 70
60 5 75
6 85
mA kHz %
80 150
110 250 8000
350
Vpp Hz pF
Bonding Diagram:
ELEN
VDD
PAD
EL1 EL2 COIL VSS HON CAP2 CAP1 VDD
X
586.0 586.0 586.0 80.0 562.5 565.0 562.5 588.0
Y
107.0 -143.0 -376.0 -417.0 -397.0 -118.0 114.5 417.0
CAP 1
EL 1
CAP 2
EL 2 SP4427
664A
VSS
COIL
NOTES: 1. Dimensions are in Microns unless otherwise noted. 2. Bonding pads are 125x125 typ. 3. Outside dimensions are maximum, including scribe area. 4. Die thickness is 380 +/- 25 microns (15 mils +/- 1). 5. Pad center coordinates are relative to die center. 6. Die size 1498 x 1168 ( 59 x 46 mils).
SP4427DS/01
SP4427 Electroluminescent Lamp Driver
(c) Copyright 1997 Sipex Corporation
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PIN DESCRIPTION
THEORY OF OPERATION The SP4427 is made up of three basic circuit elements: an oscillator, coil, and switched H-bridge network. The oscillator portion of the circuit is divided into two precision oscillators. The oscillators set the coil and lamp frequencies independently. This allows for the arbitrary setting of the coil/lamp frequency ratio. The coil frequency can be selected for maximum energy transfer per cycle for a given external coil value. The coil oscillator is set at 75% duty cycle and the lamp oscillator is set at 50% duty cycle for minimum DC offset across the EL lamp. An external capacitor connected between pin 8 and VSS allows the user to vary the lamp oscillator frequency from 75Hz to 350Hz. Likewise, an external capacitor connected between pin 1 and VSS allows the user to vary the coil oscillator frequency from 3.5kHz to 50kHz. The graphs on page 6 show the relationship between oscillators (LOSC and COSC) and their respective capacitor values. The coil is an external component connected from Vbattery to pin 3 of the SP4427. Energy is developed in the coil according to the equation EL=1/2LI2 where the current I is defined as I = (Vbattery-IRVOL)/RT. In order to maximize the energy produced by the coil Vbattery should represent the largest
SP4427CN
1 2 3 4
8 7 6 5
Pin 1 - Cosc- Connect Cap1 from Vss to pin 1 to set oscillator frequency. Pin 2 - Vss- Power supply common, connect to ground. Pin 3 - Coil- Coil input, connect coil from Vbattery to pin 3. Pin 4 - EL2- Lamp driver output1, connect to EL lamp. Pin 5 - EL1- Lamp driver output2, connect to EL lamp. Pin 6 - Vdd- Power supply for driver, connect to system Vdd. Pin 7 - HON- Enable for driver operation, high = active; low = inactive. Pin 8 - Losc- Connect Cap2 from Vss to pin 8 to set lamp frequency.
Vbat + Vbat + 0.1F
Place as close as possible to IC pin 6 Low ESR CAP
L1 20 mH/70 6 OSC 1 3
200 pF
1
Coil EL DRIVER OSC 2
5
EL Lamp 4
1800 pF
8
Lamp 2
HON
7
SP4427
SP4427 Schematic
SP4427DS/01 SP4427 Electroluminescent Lamp Driver (c) Copyright 1997 Sipex Corporation
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voltage in the system (up to the maximum tolerance of the coil) and the coil should have low resistance and high inductance; Vbattery= 1.5 VDC with a 20mH/70 coil are typical. The majority of the current goes through the coil and typically less than 1mA is required for Vdd of the SP4427. Vdd can range from 1.1V to 5V; it is not necessary that Vdd=Vbattery. Coils are also a function of the core material and winding used -- performance variances may be noticeable from different coil suppliers. The Sipex SP4427 is final tested using a 20mH/ 70 coil from CTC. For suggested coil sources see page 7. 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 90% duty cycle signal. During the time when the Fcoil signal is high, the coil is connected from Vbattery to ground and a charged magnetic field is created in the coil. During the low part of Fcoil , 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. Fcoil will send as many charge pulses as possible in 1 Lamp Cycle {Number of Coil pulses in 1 lamp cycle = Coil Freq Lamp Freq (2) }(see figure 2 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 page 6). 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 Flamp signal which is the oscillator frequency divided by 256. For a 64kHz oscillator, Flamp =256Hz.
CAP 2 = 1800 pF CAP 1 = 220 pF
1.5 Volt Application
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 55V (typ) on pins 4 and 5 which are 180 degrees out of phase with each other (see figure 3 page 6). A differential view of the outputs is shown in figure 4 on page 6. If Line Noise is of concern it is advisable to add a decoupling cap at Vdd (low ESR type). 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. All that is required is one external inductor and capacitor. Electroluminescent backlighting is ideal when used with LCD displays, keypads, or other backlit readouts. Its main use is to illuminate displays in
1 Cosc Losc Vss Hon Vdd EL1
3.FtL
0.1F
Coil EL2
5mH/18
+
Coil
LAMP
1.6 SQ. IN.
Typical SP4427CN Application Circuit
SP4427DS/01
SP4427 Electroluminescent Lamp Driver
(c) Copyright 1997 Sipex Corporation
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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, and lastly, the inductor used. 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.
SP4427DS/01
SP4427 Electroluminescent Lamp Driver
(c) Copyright 1997 Sipex Corporation
5
Vpeak=80V (typ)
EL1 output; charge steps per half cycle based on # of coil pulses per half cycle.
Figure 1.
coil freq.
Number of coil pulses in 1 lamp cycle =
lamp freq. (2)
; 90% duty cycle.
Figure 2.
EL1 Output
-EL2 Output
Figure 3.
EL1 Output Vpp=160V (typ)
-EL2 Output Differential Representation E12.
Figure 4.
SP4427DS/01
SP4427 Electroluminescent Lamp Driver
(c) Copyright 1997 Sipex Corporation
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HITACHI METALS Ltd. Kishimoto Bldg. 2-1, Marunouchi 2-Chome, Chiyoda-Ku, Tokyo Japan Phone: 3-3284-4936 Fax: 3-3287-1945 Mr. Noboru Abe Spec.9 mH 30% 42 ohm (Max) Model: MD 735L902B
Singapore Mr Stan kaiko, Mr. Hiroshi Kai Phone: 222-8077 Fax: 222-5232
San Jose, CA Mr. Kent Oda Ph: 408 436-9505 Fx: 408 436-9601 6.8 0.3
7 0.5
Hong Kong Mr Mori Ota Phone: 2724-4188 (All Dimensions in mm) Fax: 2311-2095
3.3 0.3
6 0.3
Sankyo Shoji Co. (HK) RM 28, 9/il Thriving Ind. Centre Tsuen Wan, N.T. Hong Kong Phone: 8522 414 9268 Fax: 8522 413 6040 Contact: Mr. K.M. Chang Inductance: 29mH 20 % Resistance: 62 Ohms 10% @ 25C Part Number SK-121
8.1 0.2
11 0.2
1.5 (All Dimensions in mm)
3.3 0.2
Sankyo Shoji Co. (HK) RM 28, 9/il Thriving Ind. Centre Tsuen Wan, N.T. Hong Kong Phone: 8522 414 9268 Fax: 8522 413 6040 Contact: Mr. K.M. Chang Inductance: 65mH 15mH Resistance: 270 Ohms 15% @ 25C Part Number SK-80
3.6
5.6 Max.
0.8 2.4 (All Dimensions in mm)
CTC Coils LTD (HK) Flat L-M 14 Fl, Haribest Ind'l Bldg. 45-47 Au Pul Wan Street Fo Tan Shatin. N.T., Hong Kong Phone: 85 2695 4889 Fax: 85 2695 1842 Contact: Alfred Wong cc Marine Au Inductance: 20 mH 10% Resistance: 65 Ohms Max Model Number: CH5070AS-203K-006 Sipex No. S51208-M-1021-Sipex
25 2.0
2.5
6.5 Max
9.0 Max
All dimensions in mm
Mark Technology: North American stocking distributor for Sankyo and CTC Phone: 905-891-0165 FAX: 905-891-8534.
EL polarizers/transflector manufacturers
Nitto Denko Yoshi Shinozuka 56 Nicholson Lane San Jose, CA. 432-5480 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 (516)-223-7500 Fax (516)-868-2371
EL Lamp manufacturers
Leading Edge Ind. Inc. 11578 Encore Circle Minnetonka, MN 55343 Phone 1-800-845-6992 Nippon Graphite Peter J. Opdahl 123 NW 13th Street #308 Boca Raton, FL 33432 Phone: (407) 392-2555 Fax: (407) 392-0807 Luminescent Systems inc. (LSI) 101 Etna Road Lebanon, NH. 03766-9004 Phone: (603) 448-3444 Fax: (603) 448-33452
NEC Corporation Yumi Saskai 7-1, Shiba 5 Chome, Minato-ku, Tokyo 108-01, Japan Phone: (03) 3798-9572 Fax: (03) 3798-6134 Seiko Precision Shuzo Abe 1-1, Taihei 4-Chome, Sumida-ku, Tokyo, 139 Japan Phone: (03) 5610-7089 Fax: (03) 5610-7177 MKS 7 N. Industrial Blvd Bridgeton, NJ. 08302 Phone: (609) 451-5545 Fax: (609) 451-9096
SP4427DS/01
SP4427 Electroluminescent Lamp Driver
(c) Copyright 1997 Sipex Corporation
7
0.0256 BSC 0.012 0.003 0.189/0.197 0.0965 0.003 0.053/0.069 R .003
12.0 4 0.008 0 - 6 0.006 0.006 0.006 0.006
0.150/0.157
SP4427
0.228/0.244
SP4427
0.118 0.002
0.16 0.003 12.0 4 0.01
0.014/0.019 0.050 BSC
1 2"
0.020 0.020 1 2
0.0215 0.006 0.037 Ref
3.0 3
0.116 0.004
0.034 0.002 0.040 0.002 0.116 0.004
2"
0.013 0.005 0.118 0.002
0.004 0.002
0.118 0.004
100 SP4427 die per waffle pack
95 SP4427 per tube, no minimum quantity
50 SP4427 per tube
P
W
NSOIC-8 13" reels: P=8mm, W=12mm Minimum qty per reel CN CU 500 500
Standard qty per reel 1500 1500
Maximum qty per reel 2500 3000
SP4427DS/01
SP4427 Electroluminescent Lamp Driver
(c) Copyright 1997 Sipex Corporation
8
ORDERING INFORMATION
Model Temperature Range Package Type SP4427CN . ............................................. 0C to +70C ........................................... 8-Pin NSOIC SP4427CN/TR ......................................... 0C to +70C ........................................... 8-Pin NSOIC SP4427CX ............................................... 0C to +70C .......................................................... Die SP4427CU . ............................................. 0C to +70C ........................................... 8-Pin USOIC SP4427CU/TR ......................................... 0C to +70C ........................................... 8-Pin USOIC SP4427NEB ............................................................................................ NSOIC Evaluation Board SP4427UEB ............................................................................................ USOIC Evaluation Board
Corporation
SIGNAL PROCESSING EXCELLENCE
Sipex Corporation 22 Linnell Circle Billerica, MA 01821 TEL: (508) 667-8700 FAX: (508) 670-9001 491 Fairview Way Milpitas, CA 95035 TEL: (408) 945-9080 FAX: (408) 946-6191 US Regional Sales Offices: 22 Linnell Circle Billerica, MA 01821 EASTERN U.S.: TEL: (508) 667-8700 FAX: (508) 670-9001 WESTERN U.S.: TEL: (508) 667-8700 FAX: (508) 670-9001 European Sales Offices: GERMANY: Sipex GmbH Gautinger Strasse 10 82319 Starnberg TEL: 49.81.51.89810 FAX: 49.81.51.29598 FRANCE: Sipex 30 Rue du Morvan, SILIC 525 94633 Rungis Cedex TEL: 33.1.4687.8336 FAX: 33.1.4560.0784 Far East: JAPAN: Nippon Sipex Corporation Yahagi No. 2 Building 3-5-3 Uchikanda, Chiyoda-ku Tokyo 101, Japan TEL: 011.81.3.3256.0577 FAX: 011.81.3.3256.0621
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. SP4427DS/01 SP4427 Electroluminescent Lamp Driver (c) Copyright 1997 Sipex Corporation
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