Supertex inc. HV857. Low Noise, High Voltage EL Lamp Driver IC + _. Features. General Description. Applications. Typical Application Circuit HV857

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1 Low Noise, High Voltage EL Lamp river IC Features Patented audible noise reduction Patented lamp aging compensation 90 V PP output voltage for higher brightness Patented output timing for high efficiency Single cell lithium ion compatible 0nA shutdown current Wide input voltage range. to.0v Separately adjustable lamp and converter frequencies Output voltage regulation Split supply capability Available in Lead MSOP and FN packages Applications LC backlighting Mobile Cellular Phone PAs Handheld wireless communication products Global Positioning Systems (GPS) General escription The Supertex is a high voltage driver designed for driving Electroluminescent (EL) lamps of up to.0 square inches. The input supply voltage range is from. to.0v. The device uses a single inductor and a minimum number of passive components. The nominal regulated output voltage that is applied to the EL lamp is ±9V. The chip can be enabled/disabled by connecting the resistor on to /. The has two internal oscillators, a switching MOSFET, and a high voltage EL lamp driver. The frequency for the switching MOSFET is set by an external resistor connected between the pin and the supply pin. The EL lamp driver frequency is set by an external resistor connected between REL Osc pin and pin. An external inductor is connected between the and pins or for split supply applications. A µF capacitor is connected between and ground. The EL lamp is connected between and. The switching MOSFET charges the external inductor and discharges it into the capacitor at. The voltage at will start to increase. Once the voltage at reaches a nominal value of 9V, the switching MOSFET is turned OFF to conserve power. The outputs and are configured as an H bridge and are switching in opposite states to achieve ±9V across the EL lamp. Typical Application Circuit ON = V OFF = 0 Enable Signal V C _ EL Lamp _ C IN L X C S oc.# SFP A00

2 Ordering Information Pin Configuration Part Number Package Packing KG Lead FN 000/Reel MGG Lead MSOP 00/Reel G denotes a lead (Pb)free / RoHS compliant package Absolute Maximum Ratings Parameter Value Supply voltage, V 0.V to.v Operating temperature 0 C to C Storage temperature C to 0 C FN power dissipation.w MSOP power dissipation 00mW Output voltage, V 0. to 0V Absolute Maximum Ratings are those values beyond which damage to the device may occur. Functional operation under these conditions is not implied. Continuous operation of the device at the absolute rating level may affect device reliability. All voltages are referenced to device ground. Lead FN (top view) Pads are at the bottom of the package. Exposed center pad is at ground potential. Product Marking H YWLL Lead MSOP (top view) Y = Last igit of Year Sealed W = Code for Week Sealed L = Lot Number = Green Packaging Package may or may not include the following marks: Si or Lead FN Top Marking Typical Thermal Resistance Package Lead FN Lead MSOP θ ja O C/W O C/W Mounted on FR board, mm x mm x.mm H LLLL Bottom Marking YYWW L = Lot Number YY = Year Sealed WW = Week Sealed = Green Packaging Package may or may not include the following marks: Si or Lead MSOP Recommended Operating Conditions Sym Parameter Min Typ Max Units Conditions V Supply voltage..0 V f EL Operating drive frequency.0 khz T A Operating temperature 0 O C Enable/isable Function Table Sym Parameter Min Typ Max Units Conditions ENL Logic input low voltage 0 0. V V =. to.0v ENH Logic input high voltage V 0. V V V =. to.0v C Electrical Characteristics (Over recommended operating conditions unless otherwise specified, T A = C) Sym Parameter Min Typ Max Units Conditions R S(ON) Onresistance of switching transistor.0 Ω I = 00mA V Max. output regulation voltage 9 0 V V =. to.0v oc.# SFP A00

3 C Electrical Characteristics (cont.) Sym Parameter Min Typ Max Units Conditions V A V B Peak to Peak output voltage V V =. to.0v I Q Quiescent V supply current 0 na Osc = Low I Input current going into the pin 0 µa V =. to.0v. See Figure Input current including inductor current 0 ma See Figure * V Output voltage on V V See Figure f EL EL lamp frequency 0 0 Hz See Figure f SW Switching transistor frequency 0 khz See Figure Switching transistor duty cycle % See Figure * The inductor used is a 0µH Murata inductor, max C resistance of.ω, part # LQHCNK. Block iagram Switch Osc isable C _ V V REF V SENSE Q Q High Voltage Level Translator EL Osc Q Q Figure : Typical Application/ Test Circuit ON = V OFF = 0V V Enable Signal 0kΩ 0.µF.0MΩ.µF.0kΩ BAS 0µH* Equivalent to.0in lamp.nf 00V 0nF * Murata Inductor LQHCNK oc.# SFP A00

4 Typical Performance evice Lamp Size V = V f EL Brightness MGG.0in.V 0.0mA V 0Hz.0ftlm Typical Performance Curves for Figure (EL Lamp =.0in, V =.0V) V 9 V vs l IN (ma) vs Brightness (ftlm) Brightness vs..... l IN (ma) 0 vs V 9 V 00, V, Brightness vs Inductor Value 90 0 V 0 l IN (ma), V Brightness Brightness (ftim) 0 0 l IN Inductor Value (µh) oc.# SFP A00

5 External Component escription External Component iode C S Capacitor escription Fast reverse recovery diode, BAS diode or equivalent. 0.00µF to 0.µF, 00V capacitor to is used to store the energy transferred from the inductor. The EL lamp frequency is controlled via an external resistor connected between and of the device. The lamp frequency increases as decreases. As the EL lamp frequency increases, the amount of current drawn from the battery will increase and the output voltage V will decrease. The color of the EL lamp is dependent upon its frequency. Resistor A MΩ resistor would provide lamp frequency of 0 to Hz. ecreasing the resistor by a factor of will increase the lamp frequency by a factor of. f EL = (MΩ)(0Hz) Resistor The switching frequency of the converter is controlled via an external resistor, RSW between and of the device. The switching frequency increases as decreases. With a given inductor, as the switching frequency increases, the amount of current drawn from the battery will decrease and the output voltage, V, will also decrease. f SW = (0kΩ)(0Hz) L X Inductor The inductor L X is used to boost the low input voltage by inductive flyback. When the internal switch is on, the inductor is being charged. When the internal switch is off, the charge stored in the inductor will be transferred to the high voltage capacitor C S. The energy stored in the capacitor is connected to the internal Hbridge, and therefore to the EL lamp. In general, smaller value inductors, which can handle more current, are more suitable to drive larger size lamps. As the inductor value decreases, the switching frequency of the inductor (controlled by ) should be increased to avoid saturation. A 0µH Murata (LQHCN) inductor with.ω series C resistance is typically recommended. For inductors with the same inductance value, but with lower series C resistance, lower resistor value is needed to prevent high current draw and inductor saturation. Lamp As the EL lamp size increases, more current will be drawn from the battery to maintain high voltage across the EL lamp. The input power, ( x ), will also increase. If the input power is greater than the power dissipation of the package, an external resistor in series with one side of the lamp is recommended to help reduce the package power dissipation. oc.# SFP A00

6 Split Supply Configuration The can also be used for handheld devices operating from a battery where a regulated voltage is available. This is shown in Figure. The regulated voltage can be used to run the internal logic of the. The amount of current necessary to run the internal logic is 0µA Max at a V of.0v. Therefore, the regulated voltage could easily provide the current without being loaded down. Enable/isable Configuration The can be easily enabled and disabled via a logic control signal on the and resistors as shown in Figure below. The control signal can be from a microprocessor. The control signal has to track the V supply. and are typically very high values. Therefore, only 0 s of microamperes will be drawn from the logic signal when it is at a logic high (enable) state. When the microprocessor signal is high the device is enabled, and when the signal is low, it is disabled. Figure : Split Supply and Enable/isable Configuration ON = V OFF = 0V Regulated Voltage = V Enable Signal C EL Lamp C IN L X C S Audible Noise Reduction This section describes a method (patented) developed at Supertex to reduce the audible noise emitted by the EL lamps used in application sensitive to audible noise. Figure shows a general circuit schematic that uses the resistor, R SER, connected in series with the EL lamp. Figure : Typical Application Circuit for Audible Noise Reduction ON = V Enable OFF = 0V V C R SER EL Lamp C IN L X C S oc.# SFP A00

7 Minimization of EL Lamp Audible Noise The EL lamp, when lit, emits an audible noise. This is due to EL lamp construction and it creates a major problem for applications where the EL lamp can be close to the ear such as cellular phones. The noisiest waveform is a square wave and the quietest waveform has been assumed to be a sine wave. After extensive research, Supertex has developed a waveform that is quieter than a sine wave. The waveform takes the shape of approximately RC time constants for rising and RC time constants for falling, where C is the capacitance of the EL lamp, and R is the external resistor, R SER, connected in series with the EL lamp. This waveform has been proven to generate less noise than a sine wave. Effect of Series Resistor on EL Lamp Audible Noise and Brightness As EL lamp ages, its brightness is reduced and its capacitance is diminished. By using the RC model to reduce the audible noise emitted by the EL lamp, the voltage across the lamp will increase as its capacitance diminishes. Hence the increase in voltage will compensate for the reduction of the brightness. As a result, it will extend the EL lamp s halflife (half the original brightness). Increasing the value of the series resistor with the lamp will reduce the EL lamp audible noise as well as its brightness. This is due to the fact that the output voltage across the lamp will be reduced and the output waveform will have rounder edges. The audible noise from the EL lamp can be set at a desired level based on the series resistor value used with the lamp. It is important to note that use of this resistor will reduce the voltage across the lamp. Reduction of voltage across the lamp will also have another effect on the over all performance of the Supertex EL drivers, age compensation (patented). This addresses a very important issue, EL lamp life that most mobile phone manufacturers are concerned about. oc.# SFP A00

8 Lead FN Package Outline (K).00x.00mm body, 0.0mm height (max), 0.mm pitch E E Note (Index Area / x E/) Note (Index Area / x E/) b e Top View Bottom View Note View B θ A A Seating Plane L L A Side View Note View B Notes:. A Pin identifier must be located in the index area indicated. The Pin identifier can be: a molded mark/identifier; an embedded metal marker; or a printed indicator.. epending on the method of manufacturing, a maximum of 0.mm pullback (L) may be present.. The inner tip of the lead may be either rounded or square. Symbol A A A b E E e L L θ imension (mm) MIN *.0.* * 0 O NOM REF BSC MAX *.0.* O JEEC Registration MO9, Variation WEEC, Issue C, Aug. 00. * This dimension is not specified in the JEEC drawing. rawings not to scale. Supertex oc. #: SPFNKXP0, Version C009. oc.# SFP A00

9 Lead MSOP Package Outline (MG).00x.00mm body,.0mm height (max), 0.mm pitch θ Note (Index Area / x E/) E E L Gauge Plane L L θ Seating Plane Top View View B View B A A A A e Side View b Seating Plane A View AA Note:. A Pin identifier must be located in the index area indicated. The Pin identifier can be: a molded mark/identifier; an embedded metal marker; or a printed indicator. Symbol A A A b E E e L L L θ θ imension (mm) MIN 0.* *.*.0* O O NOM BSC REF BSC MAX *.*.0* 0.0 O O JEEC Registration MO, Variation AA, Issue E, ec. 00. * This dimension is not specified in the JEEC drawing. rawings are not to scale. Supertex oc. #: SPMSOPMG, Version H009. (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to does not recommend the use of its products in life support applications, and will not knowingly sell them for use in such applications unless it receives an adequate product liability indemnification insurance agreement. does not assume responsibility for use of devices described, and limits its liability to the replacement of the devices determined defective due to workmanship. No responsibility is assumed for possible omissions and inaccuracies. Circuitry and specifications are subject to change without notice. For the latest product specifications refer to the (website: http//) 0 All rights reserved. Unauthorized use or reproduction is prohibited. oc.# SFP A00 9 Bordeaux rive, Sunnyvale, CA 909 Tel: 0