1 HV843DB1 general description the supertex HV843DB1 demo board contains all necessary circuitry to demonstrate the features of the hv843 dual el lamp driver. simply connect it to a power supply and a lamp as shown below. for additional assistance in designing el driver circuits, please refer to application notes an- h33 (effect of external components on performance of supertex el drivers). board layout and connection diagram low noise, dual el lamp driver connections: controls c 1 and c 2 : lamp selection various modes of the device are selected via the c 1 and c 2 pins. when c 1 is connected to v dd /gnd, lamp 1 (el 1 ) will be on/off. when c 2 is connected to v dd /gnd, lamp 2 (el 2 ) will be on/off. when both c 1 and c 2 are connected to gnd, the device shuts down. these inputs may be connected to a mechanical switch, or to a logic circuit output that has a source impedance of less than 20k. v dd : ic supply supplies the hv843 el driver ic. the supplied circuit is optimized for 3.0v operation. v in : inductor supply supplies the high voltage power converter. the demoboard is optimized for 3.3v to 4.2v operation. gnd: circuit ground connect to v dd and v in negative terminals. supply bypass capacitor for both v dd and v in are provided on the demo board. external supply bypass capacitors are not necessary. el 1 and el 2 : lamp connections connects to lamps 1 and 2. polarity is irrelevant. com: lamp connections connects to the other side of lamps 1 and 2. polarity is irrelevant. actual size: 17.3mm x 14.4mm speci? cation value v dd input voltage 3.0v v in inductor supply voltage 3.3v - 4.2v supply current 13ma lamp size 2.3in 2 lamp frequency 195hz converter frequency 98khz com el 1 el 2 com c 1 v dd c 2 gnd v in
2 062206 HV843DB1 figure1: HV843DB1 circuit schematic 4.7f 1n4148 c s 3.3nf 0.1f + - v dd + - v in 1 2 3 4 5 6 7 8 9 10 0=off v ih =on 0=off v ih =on c in c dd l x r sw-osc v dd com c 2 gnd el 2 l x c s el 1 c 1 r sw-osc hv843k7-g el lamp 1 el lamp 2 typical performance the speci? c external components used in the above circuit are: r sw = 845k, l x = 330h coilcraft (lps3010-334ml), c s = 3.3nf 100v npo. the following performance was observed when driving el 1 = 1.3in 2 and el 2 = 0.93in 2 green lamps. v dd (v) v in (v) lamp i in (ma) v cs (v peak )f el (hz) lamp brightness (cd/m 2 ) el 1 el 2 3.0 3.3 el 1 on 8.96 88 195 17.04 - el 2 on 6.96 - 16.36 el 1 and el 2 on 12.35 16.17 14.72 3.7 el 1 on 7.65 17.45 - el 2 on 5.98 - 16.78 el 1 and el 2 on 11.13 16.64 15.79 4.2 el 1 on 6.19 17.71 - el 2 on 4.79 - 17.20 el 1 and el 2 on 8.51 17.27 16.20 bill of materials components description package manufacturer part number l x 330h inductor --- coilcraft lps3010-334ml c s 3.3nf, 100v, npo chip capacitor 0805 novacap 0805n332k101nt r sw 1%, 845k chip resistor 0805 any --- c in 4.7f, 10v ceramic chip capacitor 0805 any --- c dd 0.1f, 16v ceramic chip capacitor 0805 any --- diode 100v fast recovery diode sot-23 diodes inc 1n4148 u1 el driver ic mlp/dfn-10 supertex inc hv843k7-g the above circuit may need to be optimized further based on speci? cation of the lamp used.
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