Optoelectronics. Application Note. The Basics of Light Emitting Diodes INTRODUCTION PRINCIPLE OF EMISSION OF VISIBLE EMITTING DIODE (LED)

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1 Application te INTRODUCTION Light Emitting Diodes or LEDs are generally classified as infrared emitting diodes or visible LEDs depending on the wavelength of the light they emit. This application note provides information on visible LEDs. Refer to the Data Book for information on infrared emitting diodes. Epoxy resin Au wire LED chip PN junction PRINCIPLE OF EMISSION OF VISIBLE EMITTING DIODE (LED) When a forward voltage is applied to the external lead pins, a current flows through the P-N junction and light is emitted from the LED chip. When no voltage is applied to the P-N junction of an LED, the junction is in thermal equilibrium as shown in Figure 2 (a). The Fermi level of the is the same as that of the, so that the height of the potential barrier is set at V D. When a forward voltage VF is applied to the junction, the height of the potential barrier is reduced to V D - V F as shown in Figure 2 (b). As a result, the holes in the P layer and the electrons in the are injected into the other layer and diffused. This injection of carriers causes excessively high carrier concentration compared with that in the thermal equilibrium state. The P- N junction tends to return to its stable thermal equilibrium state, thus recombination of carriers occurs. Simultaneously, light is emitted with an energy equal to the energy difference between those of the two carriers before recombination. The peak emission wavelength of the emitted light (λ) differs according to the energy released during recombination and the energy differs according to the material. Pin (Enlarged view of LED chip) Figure 1. Basic Structure of LED Holes Light Recombination Recombination Light VD: Potential barrier Electrons Conduction band (a) Thermal Equilibrium State VD VF Fermi level Forbidden band Valence band Conduction band Fermi level Forbidden band Valence band (b) When a Forward Voltage is Applied Figure 2. Band Model of PN Junction Eg OP10-1 OP10-2 Application te 1

2 GENERAL LED CHARACTERISTICS Absolute Maximum Ratings Conditions which should never be exceeded to prevent destruction of the LED and which correlate with the operating temperature. Continuous Forward Current (I F ), Peak Forward Current (I FM ) Current which causes the LED to emit light. Since the LED generates a certain amount of heat as current flows which affects the operating life, the current is limited by a forward current derating curve. Reverse voltage (V R ) An LED is a diode designed for its light emitting characteristics. Unlike ordinary diodes, the reverse voltage cannot be controlled by changing the concentration of the PN junction. Therefore, if a 3 V or higher reverse bias is applied, the addition of a protective circuit is recommended. Power Dissipation (P) The internal power dissipation of the LED. The life of the LED lengthens if it is used at a dissipation (junction temperature) below a certain level (temperature). Operating Temperature (T OPR ) Refers to the temperature range including the heat generated by the device during operation of the LED. Operation under conditions where damage to the package material does not occur is recommended. Storage Temperature (T STG ) Refers to the temperature range during non-operation of the LED. Since it is important for the LED package to pass light, it is not possible to change the content of the filler material to improve the temperature characteristics as in IC packages. Forward Voltage (V F ) The voltage when forward current is applied to the LED. It differs according to the added impurities in the crystal material. Reverse Current (I R ) The current when reverse voltage is applied. It is sufficiently small compared to the forward current. It is recommended that a circuit which applies a reverse bias should be avoided. Luminous Intensity (I V ) Refers to the brightness measured at a distance of one feet from the light source. Common units are the µcd and mcd. The magnitude of the numeric value and the apparent brightness do not necessary correspond. In actuality, it is necessary to take into account the contrast, luminance and quantity of light. Peak Emission Wavelength (λ), Spectrum Radiation Bandwidth ( λ) These characteristics differ according to the crystal material and added impurities. Radiation Diagram, Half Value of Viewing Angle Represents the directivity distribution of the LED luminous intensity as a relative luminous intensity value. Generally, the luminous intensity is highest along the normal optical axis and decreases as the angle with respect to the optical axis increases. The angle at which the luminous intensity drops to 50% of the peak value is called the halfpower angle. It can be used as a guide showing the sharpness of the directivity. 2 Application te

3 VISIBLE LED MATERIALS Presently, most LEDs use semiconducting materials of the III-V group of chemical compounds. Gap, GaAsP and GaAlAs shown in Table 1 are three common materials for visible LEDs. GaP (Gallium Phosphide) LEDs (Red, Yellow-green, Green) GaP, with a large forbidden band width (energy difference between conduction band bottom and valence band top) of 2.26 ev, can emit light from red to green. Because of the short 550 nm basic absorption end (550 nm), this crystal is transparent to visible light. Despite the indirect transition band structure, it provides a high luminous efficiency because its emission is affected by the carrier recombination via excitons. GaP LEDs have a number of advantages. First, they have been manufactured in mass production quantities for a long time and the production technology is mature. In addition, they are free from emission wavelength deviation so that the characteristics are easy to control. Zn and O are dopants for red LEDs and N is a dopant in yellow-green LEDs to increase the luminous efficiency. The external quantum efficiency of green and yellow-green LEDs is about 0.15% and about 0.3%, respectively. This is an order of magnitude smaller than that of GaP red LEDs (4% or less for the commercially available one). However, due to their high luminous efficiency, these LEDs provide sufficiently high luminance for practical use. Since yellow-green LEDs vary in color tone, depending upon the amount of N dopant, it is important to control the amount of the N dopant. GaAs 1-x P x (Gallium-Arsenide-Phosphide) LEDs (Red, Sunset Orange, Yellow) Mixed crystals of GaP and GaAs are used. By varying the mixing ratio x, different luminous colors from red to yellow are obtained. Since the same vapor growth and the same dopant diffusion technology as for Si can be used in manufacturing this material, it was the first put to practical use as an LED material. The relation between the x value and emission wavelength is as shown in Table 1. With x 0.4 the crystal structure changes from a direct transition type to an indirect transition type. Nitrogen is doped in orange (x = 0.65) and yellow (x = 0.85) LEDs to improve the luminous efficiency as in the GaP LEDs. Commercially available orange and yellow LEDs generally provide luminous efficiency of about 0.3% and about 0.12%, respectively. CRYSTAL MATERIAL Table 1. Crystal Material and Radiation Color (Emission Wavelength) RADIATION COLOR FORBIDDEN BAND (ev) PEAK EMISSION WAVELENGTH (nm) SERIES (AlxG a1 -x) y In 1-y P Red ZR (AlxG a1 -x) y In 1-y P Orange ZJ (AlxG a1 -x) y In 1-y P Sunset Orange ZS (AlxG a1 -x) y In 1-y P Amber ZV (AlxG a1 -x) y In 1-y P Yellow-green ZE (AlxG a1 -x) y In 1-y P Green ZG GaP: ZnO Red PR GAP: N Yellow-green EG GaP Green KG GaA S0.35 P 0.65 Red HD GaA S0.25 P 0.75 Sunset Orange HS GaA S0.15 P 0.85 Yellow HY Ga 0.63 Al 0.37 As Red TR, UR Application te 3

4 Ga 1-x Al x As (Gallium-Aluminum-Arsenide) LEDs (Red) Mixed crystal of GaAs and AlAs is used. Commercially available Ga 1-x Al x As LEDs have a mixing ratio x of 0.37, peak emission wavelength of 660 nm and luminous efficiency of about 15% or less. GaP and GaAsP LEDs are available as red LEDs. However neither of them is suitable for high luminance display applications because the GaP LED is saturated in luminance over a certain current, and the GaAsP LED provides low luminous efficiency. This is why the super luminosity GaAlAs LED lamp has been developed recently for commercial use. The single heterojunction structure is shown in Figure 3 (a) in which a P-Ga 0.65 Al 0.35 As layer is grown on the P-GaAs substrate. Then a N-Ga 0.3 Al 0.7 As layer is grown on top so that light is emitted by the former layer. With this structure, although the internal luminous efficiency is high, the external luminous efficiency is low because the light is partially absorbed by the substrate and the P-GaAlAs layer before being emitted from the crystal. The light absorption by the P-GaAlAs layer is decreased in a double heterojunction structure shown in Figure 3 (b) in which a clad layer with higher mixing ratio of AlAs is applied. Figure 3 (c) shows another double heterojunction structure which was developed for substantially improved luminous efficiency. After liquid phase epitaxial crystal growth, the GaAs substrate is removed by etching, and a is deposited appropriately to reflect the downward light in the crystal, thus increasing the external luminous efficiency. The LED with this double heterojunction provides the highest luminous efficiency of all currently available LEDs. Its application includes outdoor LED information boards and highmounted stop lamps. (Al x Ga 1-x ) y In 1-y P LEDs (Red to Green) These LEDs contain a mixture of A 10.5 In 0.5 P and Ga 0.5 In 0.5 P crystals, the latter being a ternary mixed crystal with its lattice matching that of the GaAs substrate. These LEDs are generally referred to as quadcrystal LEDs and feature an emission spectrum that can be controlled by varying the mixing ratio (x) of Al. As with AlGaAs, the quad crystal is a direct transition type, yet it has a forbidden bandwidth greater than that of AlGaAs. This enables the device to deliver superior luminosity at a shorter wavelength than does the AlGaAs LED. As shown in Figure 4, this quad crystal covers an emission wavelength of 650 to 560 nm as the Al mixing ratio is varied from 0 to N-Ga1-X AlX As(X=0.7) P-Ga1-X AlX As(X=0.35) P-GaAs(substrate) N-Ga1-X AlX As(X=0.7) P-Ga1-X AlX As(X=0.35) P-Ga1-X AlX As(X=0.7) P-GaAs(substrate) N-Ga1-X AlX As(X=0.7) P-Ga1-X AlX As(X=0.35) P-Ga1-X AlX As(X=0.7) Band gap Eg (ov) P X=0 Hole Hole Hole Figure 3. Chip Structures of GaAlAs LED AlP GaP InGaP (a) Single Heterojunction LED (b) Double Heterojunction LED (c) Double Heterojunction LED InAlP InGaP GaAs Substrate InAlP Electron Electron P P P N X=0 X=0.7 X=0.7 X=0.35 Electron Figure 4. Bandgap of (Al x Ga 1-x )In 1-y P Material P X=0.7 InP Indirect transition (including ) P X=0.35 P N X=0.7 N hγ hγ hγ X=0.35 X=0.7 OP10-3 Direct transition (including ) Lattice number a (Å) Emission wavelength λp (µm) OP Application te

5 Red LEDs with low Al mixing ratios have a quantum efficiency of approximately 3.4 percent, which diminishes as the Al mixing ratio is increased. Green LEDs, which have the highest Al mixing ratio, have a quantum efficiency as low as around 0.06 percent. Given the visual sensitivity of the human eye, the highest luminous intensity is obtained at emission wavelengths between orange (630 nm) and yellow (590 nm). Figure 5 (a) illustrates the structure of the generalpurpose, low-current (Al x Ga 1-x ) y In 1-y P LEDs. An n-(al x Ga 1-x ) 0.5 In 0.5 P cladding layer, (Al x Ga 1-x ) 0.5 In 0.5 P active layer, and p-(al x Ga 1-x ) 0.5 In 0.5 P cladding layer are sequentially deposited on an n-gaas substrate to form a double heterojunction structure. Luminous efficiency can be enhanced by making the Al mixing ratio (x) in the cladding layer higher than that in the active layer as injected carriers can be easily confined within the active layer. (Al x Ga 1-x ) y In 1-y P LEDs are fitted with an optical reflection layer known as DBR (Distributed Bragg Reflector, which combines mixed crystal layers having different refractive indexes) between the substrate and the n-(al x Ga 1-x ) 0.5 In 0.5 P cladding layer to further enhance luminous efficiency. Figure 5 (b) illustrates the current blocking structure, in which a current blocking layer is inserted immediately under the. The current blocking layer blocks the current that would otherwise pass under the electrode, thereby enabling the luminosity to be efficiently extracted from the active layer and thus providing even higher luminous intensity. Because quad-crystal LEDs are capable of a broader emission range from red to green, they are expected to replace the conventional high-luminance AlGaAs LEDs used in outdoor display boards and the low-current LEDs used in cellular phones. PRECAUTIONS FOR USE Table 2 shows precautions that must be taken to protect the quality and reliability of LED products. Current diffusion layer p-(al XGa 1-X) 0.5 In 0.5 P cladding layer (Al XGa 1-X) 0.5 In 0.5 active layer n-(ai XGa 1-X) 0.5 In 0.5 Pcladding layer n-dbr layer n-gaas layer Current diffusion layer Current blocking layer p-(al XGa 1-X) 0.5 In 0.5 P cladding layer (Al XGa 1-X) 0.5 In 0.5 P active layer n-(al XGa 1-X) 0.5 In 0.5 P cladding layer n-dbr layer n-gaas layer (a)low current LED (b)current blocking type LED Figure 5. Structures of (Al x Ga 1-x ) y In 1-y P LED OP10-5 Table 2. Precautions for Use CLASSIFICATIONS TYPE LED PRODUCTS A Lead pin type LED lamps (except for mini-mold LED lamps, chip LED devices) LED panel displays (LT9200x, LT9230x series and thin case mold type) LEDs for bar graphic displays (all resin mold type) B Mini-mold type Mini-mold LED lamps C Substrate type NOTE: x in part number indicates alphabet which shows emission color. Numeric LEDs (substrate type) Dot matrix LEDs (LT5007xx and LT5008xx and LT5013T and LT50414S series) D Case mold type LED panel displays (LT9002x, LT9010x, LT9210x, and LT9220x, LT9400x series) Numeric LEDs (mold type) Dot matrix LEDs LEDs for bar graphic display (case mold type) E Chip device type Chip LED devices Application te 5

6 Lead Pin Type LEAD FORMING METHOD Avoid forming a lead pin with the lead pin base as a fulcrum: be sure to hold a lead pin firmly when forming. Lead pins should be formed before soldering. When an LED lamp is mounted on a double-sided PWB, the heat during soldering affects the resin; therefore, keep the LED lamp more than 1.6 mm afloat above the PWB. 1.6 mm Hold a lead pin firmly when forming OP10-8 Figure 8. LED Lamp Mounted Directly on a PWB Figure 6. Lead Forming Method OP10-6 INSTALLATION Installation on a PWB When mounting an LED lamp on a PWB, do not apply physical stress to the lead pins. Installation Using a Holder When a holder is used during an LED lamp positioning, holder A should be designed to be smaller than the inside diameter of the lead pins. Holder B should be designed to be larger than the outside diameter of the lead pins. Holder A Figure 9. Installation Using a Holder B OP10-9 PWB 1. The lead pin pitch should match the PWB pin-hole pitch: absolutely avoid widening or narrowing the lead pins. 2. When positioning an LED lamp, basically employ an LED with tie-bar cut or use a spacer. Figure 7. Installation on a PWB OP10-7 NOTE: Pay attention to the thermal expansion coefficient of the material used for the holder. Since the holder expands and contracts as a result of preheat and soldering heat, mechanical stress may be applied to the lead pins, resulting in disconnection. Installation to the Case When the LED is fixed to a case as showin in Figure 10, do not fix part A with adhesives. A hole of the case should be designed to be smaller than the outside diameter of LED lamp resin. A When an LED Lamp is Mounted Directly on a PWB If the bottom face of an LED lamp is mounted directly on single-sided PWB, the base of the lead pins may be subjected to physical stress caused by PWB warp, cutting or clinching of lead pins. Prior to use, be sure to check that no disconnection inside of the resin or damage to resin etc., is found. Case Figure 10. Installation to the Case OP Application te

7 SOLDERING CONDITIONS Solder the lead pins under the conditions shown in Table 3. TYPE OF SOLDERING Manual soldering Wave soldering Reflow soldering Table 3. Soldering Conditions CONDITIONS 295 C ±5 C, within 3 seconds. 260 C ±5 C, within 5 seconds. Preheating 70 C to 80 C, within 30 seconds. Soldering 245 C ±5 C, within 5 seconds 1. Avoid dipping resin into soldering bath. 2. Avoid applying stress to lead pins while they are heated. For example, when the LED lamp is moved with the heat applied to the lead pins during manual soldering or solder repair, disconnection may occur. The package resin may be penetrated by solvents used in. Refer to Table 4 for usable solvents. and to Table 5 for Cleaning Methods. SOLVENT Ethyl alcohol Isopropyl alcohol Chloresen Acetone Trichlorethylene Table 4. Solvents NOTE: There is a world-wide movement to restrict the use of chlorofluorocarbon (CFC) based solvents and we recommend that you avoid their use. However, before using a CFC substitute solvent, carefully check that it will not penetrate the package resin. Table 5. Cleaning Methods METHOD REMARKS Soldering iron OP10-11 Solvent Ultrasonic / Immersing up to one minute at room temperature Test the under actual conditions and check for abnormalties before actual use 1. The effect on the device from ultrasonic differs depending on the size of the bath, ultrasonic output, duration, board size and device mounting method. 2. Cleaning with water is not allowed with the lead pins resin-tubulated: water may remain, thus causing the lead pins to rust. 3. Please contact our representative before using a solvent or method not given in Tables 4 and 5. Application te 7

8 Mini-mold Type LEAD FORMING METHOD Avoid forming a lead pin with the lead pin base as a fulcrum: be sure to hold a lead pin firmly when forming. Lead pins should be formed before soldering. Hold a lead pin firmly when forming Figure 11. LED Forming INSTALLATION ON A PWB When mounting on a PWB, we recommend you to: Form lead pins. Design the product so that lamps will not be mounted in the same direction as the warp of the PWB. Utilize a jig to fix location of lamps. PWB Figure 12. Mounting an LED on a PWB OP10-12 OP10-13 SOLDERING CONDITION Table 6 shows the lead pin soldering conditions. TYPE OF SOLDERING Manual soldering Wave soldering Reflow soldering Table 6. Soldering Conditions CONDITIONS 295 C ±5 C, within 3 seconds. 260 C ±5 C, within 5 seconds. 1. Avoid dipping resin into soldering bath. 2. Avoid applying stress to lead pins while they are heated. 3. Do not warp the PWB after soldering. Preheating 70 C to 80 C, within 30 seconds. Soldering 245 C ±5 C, within 5 seconds The package resin may be penetrated by solvents used in. Refer to Table 7 for usable solvents and Table 8 for Cleaning Methods. Table 7. Solvents SOLVENT Ethyl alcohol Isopropyl alcohol Chloresen Acetone Trichlorethylene OP10-16 Figure 13. Lamp Direction Soldering iron PWB OP10-14 NOTE: There is a world-wide movement to restrict the use of chlorofluorocarbon (CFC) based solvents and we recommend that you avoid their use. However, before using a CFC substitute solvent, carefully check that it will not penetrate the package resin. METHOD Solvent Ultrasonic Table 8. Cleaning Methods / REMARKS Immersing up to one minute at room temperature Test the under actual conditions and check for abnormalties before actual use Figure 14. Utilizing a Jig to Fix Location of Lamps Jig OP The effect on the device from ultrasonic differs depending on the size of the bath, ultrasonic output, duration, board size and device mounting method. 2. Please contact our representative before using a solvent or method not given in Tables 7 and 8. 8 Application te

9 SubstrateType LEAD FORMING METHOD Avoid forming a lead pin with the lead pin base as a fulcrum: be sure to hold a lead pin firmly when forming. Lead pins should be formed before soldering. Case-mold Type LEAD FORMING METHOD Avoid forming a lead pin with the lead pin base as a fulcrum: be sure to hold a lead pin firmly when forming. Lead pins should be formed before soldering. OP10-17 OP10-18 Figure 15. LED Forming Figure 16. LED Forming SOLDERING CONDITION Table 9 shows the lead pin soldering conditions. TYPE OF SOLDERING Manual soldering Wave soldering Table 9. Soldering Conditions CONDITIONS 295 C ±5 C, within 3 seconds. 260 C ±5 Cm within 5 seconds. In principle, no is required. If is required, take care to prevent the solvent from entering the package. Otherwise disconnections may occur in the LED. SOLVENT Ethyl alcohol Isopropyl alcohol Chloresen Acetone Trichlorethylene Table 10. Solvents 1. There is a world-wide movement to restrict the use of chlorofluorocarbon (CFC) based solvents and we recommend that you avoid their use. However, before using a CFC substitute solvent, carefully check that it will not penetrate the package resin. 2. The effect on the device from ultrasonic differs depending on the size of the bath, ultrasonic output, duration, board size and device mounting method. Test the method under actual conditions and check for abnormalities before actual use. 3. Please contact our representative before using a solvent or method not given in Table 10. SOLDERING CONDITION Table 11 shows the lead pin soldering conditions. TYPE OF SOLDERING Manual soldering Wave soldering Reflow soldering Table 11. Soldering Conditions CONDITIONS 295 C ±5 C, within 3 seconds. 260 C ±5 Cm within 5 seconds. Preheating 70 C to 80 C, within 30 seconds. Soldering 245 C ±5 C, within 5 seconds. The package resin may be penetrated by solvents used in. Refer to Table 12 for usable solvents and Table 13 for Cleaning Methods. Table 12. Solvents SOLVENT Ethyl alcohol Isopropyl alcohol Chloresen Acetone Trichlorethylene NOTE: There is a world-wide movement to restrict the use of chlorofluorocarbon (CFC) based solvents and we recommend that you avoid their use. However, before using a CFC substitute solvent, carefully check that it will not penetrate the package resin. Application te 9

10 Table 13. Cleaning Methods Table 14. Soldering Conditions METHOD REMARKS TYPE OF SOLDERING CONDITIONS Solvent Ultrasonic / Immersing up to one minute at room temperature Test the under actual conditions and check for abnormalties before actual use Manual soldering 300 C ±5 C, within 5 seconds Preheating 100 C to 150 C, within 2 minutes. Soldering 245 C ±5 C, within 5 seconds. Gradual cooling (avoiding quenching). 1. The effect on the device from ultrasonic differs depending on the size of the bath, ultrasonic output, duration, board size and device mounting method. 2. Please contact our representative before using a solvent or method not given in Table 12. Reflow soldering Temperature(C) Within 5 s Chip LED Device Type 0 Within 2 min. 30 s MOUNTING TO A PWB Design the product so that the devices will not be mounted in the same direction as the warp of the PWB. The package resin may be penetrated by solvents used in. Refer to Table 15 for usable solvents and Table 16 for Cleaning Methods. Table 15. Solvents Figure 17. Mounting to a PWB OP10-19 SOLDERING CONDITION Solder the lead pins under the following conditions: In manual soldering, do not move the lead pins with the soldering edge. Avoid applying excessive solder reinforcement. Do not try to correct the position of the devices after soldering. Do not warp PWB after soldering. SOLVENT Ethyl alcohol Isopropyl alcohol Chloresen Acetone Trichlorethylene NOTE: There is a world-wide movement to restrict the use of chlorofluorocarbon (CFC) based solvents and we recommend that you avoid their use. However, before using a CFC substitute solvent, carefully check that it will not penetrate the package resin. METHOD Table 16. Cleaning Methods REMARKS Figure 18. Solder Reinforcement OP10-21 Solvent Ultrasonic / Immersing up to one minute at room temperature Test the under actual conditions and check for abnormalties before actual use Figure 19. PWB Warping OP The effect on the device from ultrasonic differs depending on the size of the bath, ultrasonic output, duration, board size and device mounting method. 2. Please contact our representative before using a solvent or method not given in Table Since the device is very small, it may be damaged by excessive stress. Pay special attention to the transport method and handling. 10 Application te

11 LIFE SUPPORT POLICY SHARP components should not be used in medical devices with life support functions or in safety equipment (or similiar applications where component failure would result in loss of life or physical harm) without the written approval of an officer of the SHARP Corporation. LIMITED WARRANTY SHARP warrants to its Customer that the Products will be free from defects in material and workmanship under normal use and service for a period of one year from the date of invoice. Customer's exclusive remedy for breach of this warranty is that SHARP will either (i) repair or replace, at its option, any Product which fails during the warranty period because of such defect (if Customer promptly reported the failure to SHARP in writing) or, (ii) if SHARP is unable to repair or replace, refund the purchase price of the Product upon its return to SHARP. This warranty does not apply to any Product which has been subjected to misuse, abnormal service or handling, or which has been altered or modified in design or construction, or which has been serviced or repaired by anyone other than Sharp. The warranties set forth herein are in lieu of, and exclusive of, all other warranties, express or implied. ALL EXPRESS AND IMPLIED WARRANTIES, INCLUDING THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR USE AND FITNESS FOR A PARTICULAR PURPOSE, ARE SPECIFICALLY EXCLUDED. In no event will Sharp be liable, or in any way responsible, for any incidental or consequential economic or property damage. The above warranty is also extended to Customers of Sharp authorized distributors with the following exception: reports of failures of Products during the warranty period and return of Products that were purchased from an authorized distributor must be made through the distributor. In case Sharp is unable to repair or replace such Products, refunds will be issued to the distributor in the amount of distributor cost. SHARP reserves the right to make changes in specifications at any time and without notice. SHARP does not assume any responsibility for the use of any circuitry described; no circuit patent licenses are implied. NORTH AMERICA EUROPE ASIA SHARP Microelectronics of the Americas 5700 NW Pacific Rim Blvd., M/S 20 Camas, WA 98607, U.S.A. Phone: (360) Telex: (SHARPCAM) Facsimile: (360) SHARP Electronics (Europe) GmbH Microelectronics Division Sonninstraße Hamburg, Germany Phone: (49) Facsimile: (49) SHARP Corporation Integrated Circuits Group Ichinomoto-Cho Tenri-City, Nara, 632, Japan Phone: (07436) Telex: LABOMETA-B J63428 Facsimile: (07436) by SHARP Corporation Reference Code SMA99030