Supertex inc. HV825DB1 EL Driver Demoboard General Description The HV825DB1 EL Driver demoboard contains all the circuitry necessary to drive an EL (Electroluminescent) lamp. Simply connect it to a power supply and a lamp as shown below. Specifications Parameter The supplied circuit has been optimized to drive a 1.5in2 lamp from a 1.5V supply. The circuit may be customized with different component values to suit a particular application. For additional assitance in designing EL driver circuits, please refer to Application Notes AN-H33 (EL Lamp Driver Circuits) and AN-H34 (HV823 & HV825 EL Lamp Driver Circuits). Value Supply voltage 1.5V Supply current 27mA (typical) Lamp size range 1.5in2 Lamp frequency 450Hz (typical) Converter frequency 30KHz (typical) Board Layout and Connection Diagram Enable Off connect together On CDD RSW REL CSW EN VA VDD VIN 1.5V GND 825 L CIN D CS EL Lamp VB HV825DB1 Connections: EN - Enable Input Enables/disables the lamp driver. A logic high (VDD) enables the driver and a logic low (GND) disables the driver. This input may be connected to a mechanical switch as shown, or to a logic circuit output that has a source impedance of less than 20kΩ. VDD - IC Supply Supplies the HV825 EL driver IC. The supplied circuit is optimized for 1.5V operation. Current draw is less than 1.0µA when disabled. Doc.# DSDB-HV825DB1 B032114 VIN - Inductor Supply Supplies the high voltage power converter. Current draw is approximately 27mA. GND - Circuit Ground Connect to VDD and VIN negative terminals. Supply bypass capacitors for both VDD and VIN are provided on the demo board. External supply bypass capacitors are not necessary. VA and VB - Lamp Connections Connect to EL lamp of 1.5in2. Polarity is irrelevant. Supertex inc. www.supertex.com HV825DB1 HV825DB1 Circuit Schematic Enable REL-Osc 1.0MΩ ON = VDD RSW-Osc 1.0MΩ OFF = GND VDD Note 1 VIN L 560µH CDD 100nF D 1N4148 CIN 4.7µF CS 100nF GND CSW 1.0nF VDD REL RSW VA CS VB LX GND EL Lamp HV825 Note: 1. Tie VDD and VIN together if split suppies are not used. CDD is not needed when a single supply is used. Modifiying the Supplied Circuit The demo board can be easily modified to drive 2.7in2 by changing the inductor, CS capacitor and the REL resistor. For component locations, refer to the board layout and connection diagram at the begining of this note. The circuits are designed to operate from a single 1.5V supply connected to VDD and VIN. The supplied circuit is optimized to drive a 1.5in2 green lamp. To better suit other applications, the circuit can be modified by changing one or more components. The following table lists the typical performance of the HV825 driving a 1.5in2 and a 2.7in2 lamp. (ft-lm) Lamp Color Lamp Freq 1.5 3.6 Green 450 2.7 3.3 Green 300 Lamp Size (in2) Lamp1 Brightness (Hz) VIN Current (mA) Component Values L 2 REL RSW CS (µH) (MΩ) (KΩ) (nF) 27 560 1.0 1.0 100 45 330 2.0 1.0 10 Notes: 1. Lamp brightness can vary by type and manufacturer. 2. The recommended inductor is a Murata LQH4N series. Other inductors may be used, however, different inductor characteristics (especially series resistance) may result in overall circuit performance different from that listed. Please refer to Application Note AN-H33 for more information. Supertex inc. 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.” Supertex inc. 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 Supertex inc. (website: http//www.supertex.com) Supertex inc. ©2014 Supertex inc. All rights reserved. Unauthorized use or reproduction is prohibited. Doc.# DSDB-HV825DB1 B032114 2 1235 Bordeaux Drive, Sunnyvale, CA 94089 Tel: 408-222-8888 www.supertex.com