15-17 HV823 HV823 high-voltage el lamp driver features processed with hvcmos ? technology 2.0v to 9.5v operating supply voltage dc to ac conversion 180v peak-to-peak typical output voltage large output load capability typically 50nf permits the use of high-resistance elastomeric lamp components adjustable output lamp frequency to control lamp color, lamp life, and power consumption adjustable converter frequency to eliminate harmonics and optimize power consumption enable/disable function low current draw under no load condition package options device input voltage 8-lead so die HV823 2.0v to 9.5v HV823lg HV823x ordering information general description the supertex HV823 is a high-voltage driver designed for driving el lamps of up to 50nf. el lamps greater than 50nf can be driven for applications not requiring high brightness. the input supply voltage range is from 2.0 to 9.5v. 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 90v. the chip can be enabled by connecting the resistors on r sw-osc and r el-osc to v dd and disabled when connected to gnd. the HV823 has two internal oscillators, a switching mosfet, and a high-voltage el lamp driver. the frequency for the switch- ing converter mosfet is set by an external resistor connected between the r sw-osc pin and the supply pin v dd . the el lamp driver frequency is set by an external resistor connected be- tween r el-osc pin and the v dd pin. an external inductor is connected between the l x and v dd pins. a 0.01 m f to 0.1 m f capacitor is connected between c s and gnd. the el lamp is connected between v a and v b . the switching mosfet charges the external inductor and discharges it into the c s capacitor. the voltage at c s will start to increase. once the voltage at c s reaches a nominal value of 90v, the switching mosfet is turned off to conserve power. the outputs v a and v b are configured as an h-bridge and are switched in opposite states to achieve 180v peak-to-peak across the el lamp. pin configuration va v dd r el-osc r sw-osc v a c s v b l x gnd applications handheld personal computers electronic personal organizers gps units pagers cellular phones portable instrumentation 1 2 3 4 8 7 6 5 so-8 absolute maximum ratings* supply voltage, v dd -0.5v to +10v output voltage, v cs -0.5v to +120v operating temperature range -25 c to +85 c storage temperature range -65 c to +150 c power dissipation 400mw note : *all voltages are referenced to gnd.
15-18 HV823 symbol parameter min typ max units conditions r ds(on) on-resistance of switching transistor 2 6 w i = 100ma v cs output voltage v cs regulation 80 90 100 v v in = 2.0 to 9.5v v a - v b output peak to peak voltage 160 180 200 v v in = 2.0v to 9.5v i ddq quiescent v dd supply current, disabled 30 100 na r sw-osc = low i dd input current going into the v dd pin 150 200 m av in = 3.0v. see figure 1. 300 m av in = 5.0v. see figure 2. 500 m av in = 9.0v. see figure 3. i in input current including inductor current 25 33 ma v in = 3.0v. see figure 1. v cs output voltage on v cs 60 70 85 v v in = 3.0v. see figure 1. f el v a-b output drive frequency 330 380 450 hz v in = 3.0v. see figure 1. f sw switching transistor frequency 50 60 70 khz v in = 3.0v. see figure 1. d switching transistor duty cycle 88 % electrical characteristics dc characteristics (v in = 3.0v, r sw = 750k w , r el = 2.0m w , t a = 25 c unless otherwise specified) symbol parameter min typ max units conditions v dd supply voltage 2.0 9.5 v t a operating temperature -25 +85 c recommended operating conditions r sw resistor HV823 v dd enable 0v disable enable/disable table (see figure 4)
15-19 HV823 figure 1: test circuit, v in = 3.0v (low input current with moderate output brightness). 1 7 2 3 4 8 6 5 v in = 3.0v on = v dd off = 0v 0.1 m f 100v 0.1 m f 2 560 m h 1 1n4148 750k w 2m w 2.0k w 10nf equivalent to 3 square inch lamp. HV823 l x gnd v b v a r el-osc v dd r sw-osc c s block diagram switch osc c + _ vref disable output osc gnd v dd r el-osc q q q v a c s l x v b q r sw-osc enable * * enable is available in die form only. notes: 1. murata part # lqh4n561k04 (dc resistance < 14.5 w ) 2. larger values may be required depending upon supply impedance. lamp size v in i in v cs f el brightness 3.0 in 2 3.0v 25ma 65v 385hz 6.5ft-lm typical performance for additional information, see application notes an-h33 and an-h34.
15-20 HV823 typical performance curves for figure 1 using 3in 2 el lamp. i in (ma) brightness (ft-im) i in (ma) v in (v) brightness vs. v in v in (v) i in vs. v in v cs (v) i in vs. v cs (v) v in (v) v cs vs. v in v cs (v) 123456789 0 5 10 15 20 25 30 40 50 60 70 80 90 0 5 10 15 20 25 30 123456789 0 2 4 6 8 10 12 123456789 40 50 60 70 80 90 100 250 400 550 700 850 1000 90 80 70 60 50 40 30 20 10 0 9.0 8.0 7.0 6.0 5.0 4.0 3.0 2.0 1.0 0 inductor value ( m h) i in , v cs , brightness vs. inductor value i in (ma), v cs (v) brightness (ft-im) v cs (v) brightness (ft-lm) i in (ma)
15-21 HV823 figure 2: typical 5.0v application 1 7 2 3 4 8 6 5 v in = 5.0v 0.01 m f 100v 1nf 16v 560 m h 1 1n4148 750k w 2m w 3.1k w 20nf HV823 l x gnd v b v a r el-osc v dd r sw-osc c s on = v dd off = 0v 0.1 m f 2 equivalent to 6 square inch lamp notes: 1. murata part # lqh4n561k04 (dc resistance < 14.5 w ) 2. larger values may be required depending upon supply impedance. lamp size v in i in v cs f el brightness 6.0 in 2 5.0v 25ma 75v 380hz 6.5ft-lm typical performance for additional information, see application notes an-h33 and an-h34. typical performance curves for figure 2 90 85 80 75 70 65 5 478 6 8 7.5 7 6.5 6 5.5 5 478 6 40 38 36 34 32 30 5 478 6 40 38 36 34 32 30 70 80 85 90 75 v cs (v) i in (ma) brightness (ft-im) i in (ma) v in (v) v in (v) v in (v) v cs (v) v cs vs. v in brightness vs. v in i in vs. v in i in vs. v cs (v)
15-22 HV823 figure 3: typical 9.0v application* 1 7 2 3 4 8 6 5 v in = 9.0v 0.01 m f 100v 1nf 16v 560 m h 1 1n4148 330k w 2m w 4.9k w 42nf HV823 l x gnd v b v a r el-osc v dd r sw-osc c s 0.1 m f 2 equivalent to 12 square inch lamp notes: 1. murata part # lqh4n561k04 (dc resistance < 14.5 w ) 2. larger values may be required depending upon supply impedance. lamp size v in i in v cs f el brightness 12.0 in 2 9.0v 30ma 75v 380hz 8.5ft-lm typical performance for additional information, see application notes an-h33 and an-h34. 85 80 75 70 65 5 478 6 8 7.5 7 6.5 6 5.5 5 478 6 40 38 36 34 32 30 5 478 6 40 38 36 34 32 30 70 80 85 90 75 v cs (v) i in (ma) brightness (ft-im) i in (ma) v in (v) v in (v) v in (v) v cs (v) v cs vs. v in brightness vs. v in i in vs. v in i in vs. v cs (v) typical performance curves for figure 3
15-23 external component description external component selection guide line diode fast reverse recovery diode, 1n4148 or equivalent. cs capacitor 0.01 m f to 0.1 m f, 100v capacitor to gnd is used to store the energy transferred from the inductor. r el-osc the el lamp frequency is controlled via an external r el resistor connected between r el-osc and v dd of the device. the lamp frequency increases as r el decreases. as the el lamp frequency increases, the amount of current drawn from the battery will increase and the output voltage v cs will decrease. the color of the el lamp is dependent upon its frequency. a 2m w resistor would provide lamp frequency of 330 to 450hz. decreasing the r el-osc by a factor of 2 will increase the lamp frequency by a factor of 2. r sw-osc the switching frequency of the converter is controlled via an external resistor, r sw between r sw-osc and v dd of the device. the switching frequency increases as r sw 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 cs , will also decrease. c sw capacitor a 1nf capacitor is recommended on r sw-osc to gnd when a 0.01 m f c s capacitor is used. this capacitor is used to shunt any switching noise that may couple into the r sw-osc pin. the c sw capacitor may also be needed when driving large el lamp due to increase in switching noise. lx 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 h-bridge 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 r sw ) should be increased to avoid saturation. 560 m h murata inductors with 14.5 w series dc resistance is typically recommended. for inductors with the same inductance value but with lower series dc resistance, lower r sw 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, (v in x i in ), will also increase. if the input power is greater than the power dissipation of the package (400mw), an external resistor in series with one side of the lamp is recommended to help reduce the package power dissipation. enable/disable configuration the HV823 can be easily enabled and disabled via a logic control signal on the r sw and r el resistors as shown in figure 4 below. the control signal can be from a microprocessor. r sw and r el are typically very high values. therefore, only 10s of microam- 1 7 2 3 4 8 6 5 v dd on =v dd off = 0v c s 100v 4.7 m f 15v 1nf l x 1n4148 r sw r el el lamp HV823lg l x gnd v b v a r el-osc v dd r sw-osc c s + - remote enable figure 4: enable/disable configuration peres 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. HV823
15-24 split supply configuration using a single cell (1.5v) battery the HV823 can also be used for handheld devices operating from a single cell 1.5v battery where a regulated voltage is available. this is shown in figure 5. the regulated voltage can be used to run the internal logic of the HV823. the amount of current necessary to run the internal logic is typically 100 m a at a v dd of 3.0v. therefore, the regulated voltage could easily provide the current without being loaded down. the HV823 used in this configuration can also be enabled/disabled via logic control signal on the r sw and r el resistors as shown in figure 4. split supply configuration for battery voltages of higher than 9.5v figure 5 can also be used with high battery voltages such as 12v as long as the input voltage, v dd , to the HV823 device is within its specifications of 2.0v to 9.5v. figure 5: split supply configuration 1 7 2 3 4 8 6 5 battery voltage regulated voltage on off c s 100v 0.1 m f* l x 1n4148 r sw r el el lamp HV823lg l x gnd v b v a r el-osc v dd r sw-osc c s + - remote enable *larger values may be required depending upon supply impedance. for additional information, see application notes an-h33 and an-h34. HV823
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