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Part: SP4438
Category:
Optoelectronics
-> Drivers/Controllers
-> LEDs
-> LEDs/Segment Display Drivers
Description: Ultra-quiet Electroluminescent Lamp Driver For Cellular Phone Applications
Company: Sipex Corporation
Datasheet: Download SP4438 datasheet File size : 77 kB
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Datasheet text preview:
®
SP4438
Ultra-Quiet Electroluminescent Lamp Driver For Cellular Phone Applications
s Patent Pending Output Waveshaping s Waveshaped Output Optimized For Low Acoustic Noise And Maximum Efficiency s Reduced Supply Current And Standby Current s Up to15cd/m2 For Cell Phone Sized EL Lamps (2 to 3 sq. in.) s Waveshaped Output And Low Frequency Operation Minimize Stress On EL Lamp To Extend Its Lifetime s Uses 820µH, Sub-2mm Coils s Gradual Rising And Falling Edges Minimizes EMI s +2.7V To +3.3V Battery Operation s Space-Saving 8-pin MSOP package APPLICATIONS s Cellular Radios s Wireless Communication Products
DESCRIPTION The SP4438 device is a low noise, high voltage output DC-AC inverter designed to drive electroluminescent lamps to backlight liquid crystal display and keypads used in cellular phones, cordless phones, 2-way radios, and other wireless communication products. The output waveform of the SP4438 device is ideal for cell phone applications requiring low acoustic noise performance. One external resistor is used to set the internal oscillator frequency and one inductor is required to generate the high voltage AC output to drive an EL lamp up to 3 square inches in size. The SP4438 operates from a +3.0V battery source and has a low power standby mode that draws less than 1µA, making it ideal for low-power cellular applications. All input pins are ESD protected with internal diodes to VDD and VSS. The SP4438 is offered in a space-saving 8-pin MSOP package.
VBATT
VDD 1 ELEN 2 ROSC 3 VSS 4 SP4438
8
EL1
ELEN 2 L1 820µH/14
7 EL2 6 5 CINT COIL
C1 0.1µF C2 1nF VDD ROSC 714k 1 ROSC 3 4
SP4438
5 6
COIL D1 1N4148
CINT
8 VSS EL1
7 EL2
CINT 47nF
EL Lamp
Rev. 3/19/01
SP4438 Ultra-Quiet Electroluminescent Lamp Driver
© Copyright 2001 Sipex Corporation
1
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. Supply Voltage (VDD to VSS)......-0.3V, +5V Operating Temperature.....-40°C to +85°C Storage Temperature......-65°C to +150°C Power Dissipation Per Package 8-pin MSOP (derate 4.85mW/OC above +70OC).......400mW
SPECIFICATIONS
VDD = +2.7V to +3.3V, LCOIL = 820µH/14, ROSC = 714k, EL Lamp Load = (8nF + 2.5k)/1M, and TAMB = -40OC to +85OC. TAMB = 25OC for typical values unless otherwise noted.
PARAMETER INPUT CHARACTERISTICS Supply Voltage, VDD Supply Current, ICOIL+IDD Coil Voltage, VCOIL ELEN Input Voltage, VELEN LOW: EL OFF HIGH: EL on ELEN Input Impedance Shutdown Current, ISD=ICOIL+IDD INDUCTOR DRIVE Coil Frequency, fCOIL Coil Duty Cycle Peak Coil Current, IPK-COIL EL LAMP OUTPUT EL Lamp Frequency, fLAMP Peak to Peak Output Voltage, VP-P
MIN.
TYP.
MAX.
UNITS
CONDITIONS
2.7
3.0
3.3 30
V mA V VDD = +3.0V
VDD -0.25 VDD-0.25 1 0 VDD 3
9
0.25V VDD+0.25
V M
1
µA
VELEN = LOW,VDD = +3.0V
26 23
32
43 45
kHz %
ROSC = 714k,TAMB = +25OC TAMB = -40OC to +85OC,VDD = +3.0V
90 100
mA
190 175 130 120
250
336 348
Hz
TAMB = +25OC,VDD = +3.0V,with load TAMB = -40OC to +85OC TAMB = +25OC,VDD = +3.0V,with load TAMB = -40OC to +85OC TAMB = +25OC,VDD = +3.0V, NOTE 1 TAMB = +25OC,VDD = +3.0V,with load, measured from 10% to 90%
145 140 26
VP-P dBSPL 1.0 ms
Audible Noise Rise Time .55
0.8
NOTE 1: Audible Noise is measured inside an acoustic sound chamber. The Sound Level Meter is a B&K Mediator 2238, A-weighted with Condenser Mic type 4188 positioned 1/4 inch above the lamp in an 8 cubic inch volume. See Figure 5 on page 6.
Rev. 3/19/01 SP4438 Ultra-Quiet Electroluminescent Lamp Driver © Copyright 2001 Sipex Corporation
2
PINOUT
VDD 1 ELEN 2 ROSC 3 VSS 4 SP4438
8
EL1
7 EL2 6 5 CINT COIL
PIN ASSIGNMENTS Pin 1 -- VDD -- Positive Battery Power Supply. Connect such that +2.7V < VDD < +3.3V. Pin 2 -- ELEN -- Electroluminescent Lamp Enable. When driven HIGH, this input pin enables the EL driver outputs for EL1 and EL2. This pin has an internal pulldown resistor. Pin 3 -- ROSC -- Oscillator Resistor. Connecting a resistor to this input pin sets the frequency of the internal clock. Pin 4 -- VSS -- Power Supply Common. Connect to the lowest circuit potential, typically ground. Pin 5 -- COIL -- The inductor for the EL lamp is connected from VDD to this input pin. Pin 6 -- CINT -- Integrating Capacitor. An integrating capacitor (47nF typical) connected from this pin to ground filters out any coil switching spikes or ripple present in the output waveform to the EL lamp. Connecting a fast recovery diode from COIL to CINT increases the light output of the EL lamp. Pin 7 -- EL2 -- Electroluminescent Lamp Output 2. This is a high voltage lamp driver output pin to connect to the EL lamp. Pin 8 -- EL1 -- Electroluminescent Lamp Output 1. This is a high voltage lamp driver output pin to connect to the EL lamp.
Rev. 3/19/01
SP4438 Ultra-Quiet Electroluminescent Lamp Driver
© Copyright 2001 Sipex Corporation
3
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