supertex inc. supertex inc. www.supertex.com hv857 doc.# dsfp-hv857 a062013 features ? patented audible noise reduction ? patented lamp aging compensation ? 190 v pp output voltage for higher brightness ? patented output timing for high eficiency ? single cell lithium ion compatible ? 150na shutdown current ? wide input voltage range 1.8 to 5.0v ? separately adjustable lamp and converter frequencies ? output voltage regulation ? split supply capability ? available in 8-lead msop and dfn packages applications ? lcd backlighting ? mobile cellular phone ? pdas ? handheld wireless communication products ? global positioning systems (gps) general descriptionthe supertex hv857 is a high voltage driver designed for driving electroluminescent (el) lamps of up to 5.0 square inches. the input supply voltage range is from 1.8 to 5.0v. 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 95v. the chip can be enabled/disabled by connecting the resistor on rsw-osc to vdd/gnd. the hv857 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 rsw-osc pin and the supply pin vdd. the el lamp driver frequency is set by an external resistor connected between rel- osc pin and vdd pin. an external inductor is connected between the lx and vdd pins or v in for split supply applications. a 0.003- 0.1f capacitor is connected between cs and ground. the el lamp is connected between va and vb. the switching mosfet charges the external inductor and discharges it into the capacitor at cs. the voltage at cs will start to increase. once the voltage at cs reaches a nominal value of 95v, the switching mosfet is turned off to conserve power. the outputs va and vb are conigured as an h bridge and are switching in opposite states to achieve 95v across the el lamp. typical application circuit low noise, high voltage el lamp driver ic el lamp + _ c s v in l x c in enable signal on = v dd off = 0 d + _ v dd c dd r sw r el 12 3 4 87 6 5 vddrsw-osc rel-osc gnd vavb cs lx hv857 downloaded from: http:///
2 supertex inc. www.supertex.com doc.# dsfp-hv857 a062013 hv857 absolute maximum ratings parameter value supply voltage, v dd -0.5v to 6.5v operating temperature -40c to +85c storage temperature -65c to +150c dfn-8 power dissipation 1.6w msop-8 power dissipation 300mw output voltage, v cs -0.5 to +120v absolute maximum ratings are those values beyond which damage to the device may occur. functional operation under these conditions is not im - plied. continuous operation of the device at the absolute rating level may affect device reliability. all voltages are referenced to device ground. pin coniguration 8-lead mso p (top view ) pads are at the bottom of the pa ckage. exposed center pa d is at ground potential. 8-lead df n (top view ) 1 2 3 4 8 7 6 5 vdd rsw-osc rel-osc gnd vavb cs lx 1 2 3 4 8 7 6 5 vdd rsw-osc rel-osc gnd vavb cs lx typical thermal resistance package ja 8-lead dfn 37 o c/w 8-lead msop 171 o c/w mounted on fr4 board, 25mm x 25mm x 1.57mm sym parameter min typ max units conditions v dd supply voltage 1.8 - 5.0 v --- f el operating drive frequency - - 1.0 khz --- t a operating temperature -40 - +85 o c --- recommended operating conditions sym parameter min typ max units conditions en-l logic input low voltage 0 - 0.2 v v dd = 1.8 to 5.0v en-h logic input high voltage v dd - 0.2 - v dd v v dd = 1.8 to 5.0v enable/disable function table sym parameter min typ max units conditions r ds(on) on-resistance of switching transistor - - 6.0 i = 100ma v cs max. output regulation voltage 85 95 105 v v dd =1.8 to 5.0v dc electrical characteristics (over recommended operating conditions unless otherwise speciied, t a = 25c) product marking h857 ywll y = last digit of year sealedw = code for week sealed l = lot number = ?green? packaging l = lot number yy = year sealed ww = week sealed = ?green? packaging h857 llll yyww top marking bottom marking 8-lead dfn 8-lead msop package may or may not include the following marks: si or package may or may not include the following marks: si or ordering information part number package packing hv857k7-g 8-lead dfn 3000/reel hv857mg-g 8-lead msop 2500/reel -g denotes a lead (pb)-free / rohs compliant package downloaded from: http:///
3 supertex inc. www.supertex.com doc.# dsfp-hv857 a062013 hv857 block diagram * the inductor used is a 220h murata inductor, max dc resistance of 8.4, part # lqh32cn221k21. figure 1: typical application/ test circuit dc electrical characteristics (cont.) sym parameter min typ max units conditions v a C v b peak to peak output voltage 170 190 210 v v dd =1.8 to 5.0v i ddq quiescent v dd supply current - - 150 na r sw- osc = low i dd input current going into the vdd pin - - 150 a v dd = 1.8 to 5.0v. see figure 1 i in input current including inductor current - 20 25 ma see figure 1* v cs output voltage on vcs - 84 - v see figure 1 f el el lamp frequency 205 240 275 hz see figure 1 f sw switching transistor frequency - 80 - khz see figure 1 d switching transistor duty cycle - 88 - % see figure 1 c + _ v ref disa bl e high voltage level translator gn d vdd q q q va cs lx vb q rsw-osc r el-os c v sense el osc v dd switch osc 220h* 3.3nf 100v 560k? 2.0m? bas21 * murata inductor lqh32cn221k21 hv857 on = v dd off = 0v enable signal + - v n .f + - v dd 0.1f 2.0k? eialen 3.0in 2 la 10nf 12 3 6 5 vddrsw-osc rel-osc gnd vavb cs lx hv857 downloaded from: http:///
4 supertex inc. www.supertex.com doc.# dsfp-hv857 a062013 hv857 typical performance device lamp size v dd = v in i in v cs f el brightness hv857mg-g 3.0in 2 3.3v 20.0ma 84v 240hz 6.0ft-lm typical performance curves for figure 1 (el lamp = 3.0in 2 , v dd = 3.0v) i in , v cs , brightness vs inductor value 0 10 20 30 40 50 60 70 80 90 100 100 200 300 400 500 600 inductor value ( h) 0 1 2 3 4 5 6 7 brightness v cs i in vs v in 13 15 17 19 21 23 25 v in (v ) v cs (v) l in (ma) brightness (ft-lm) l in (ma) l in (ma), v cs (v) brightness (ft-im) brightness vs v in 1 2 3 4 5 6 7 1.5 2.5 3.5 4.5 5.5 v in (v) i in vs v cs 14 16 18 20 22 24 55 65 75 85 95 v cs (v ) v cs vs v in 55 65 75 85 95 v in (v ) l in 1.5 2.5 3.5 4.5 5.5 1.5 2.5 3.5 4.5 5.5 downloaded from: http:///
5 supertex inc. www.supertex.com doc.# dsfp-hv857 a062013 hv857 external component description external component description diode fast reverse recovery diode, bas21 diode or equivalent. c s capacitor 0.003f to 0.1f, 100v capacitor to gnd is used to store the energy transferred from the inductor. r el resistor the el lamp frequency is controlled via an external r el resistor connected between rel- osc and vdd 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? resistor would provide lamp frequency of 205 to 275hz. decreasing the r el resistor by a factor of 2 will increase the lamp frequency by a factor of 2. f el = (2m?)(240hz) r el r sw resistor the switching frequency of the converter is controlled via an external resistor, rsw between rsw- osc and vdd 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 th e output voltage, v cs , will also decrease. f sw = (560k?)(80hz) r sw l x inductor the inductor l x is used to boost the low input voltage by inductive lyback. 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 switch - ing frequency of the inductor (controlled by r sw ) should be increased to avoid saturation. a 220h murata (lqh32cn221) inductor with 8.4? series dc resistance is typically recommended. for inductors with the same inductance value, but with lower series dc resistance, lower r sw 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, (v in x i in ), 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 recom - mended to help reduce the package power dissipation. downloaded from: http:///
6 supertex inc. www.supertex.com doc.# dsfp-hv857 a062013 hv857 split supply coniguration the hv857 can also be used for handheld devices operating from a battery where a regulated voltage is available. this is shown in figure 2. the regulated voltage can be used to run the internal logic of the hv857. the amount of current necessary to run the internal logic is 150a max at a v dd of 3.0v. therefore, the regulated voltage could easily provide the current without being loaded down. the hv857 can be easily enabled and disabled via a logic control signal on the r sw and r el resistors as shown in fig - ure 2 below. the control signal can be from a microproces - sor. the control signal has to track the v dd supply. r sw and r el are typically very high values. therefore, only 10s 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. enable/disable coniguration figure 2: split supply and enable/disable conigurationaudible 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 3 shows a general circuit schematic that uses the resistor, r ser , connected in series with the el lamp. el lamp on = v dd off = 0v enable signal l x c s regulated voltage = v dd c in d r el r sw c dd v in + - 12 3 4 87 6 5 vddrsw-osc rel-osc gnd vavb cs lx hv857 figure 3: typical application circuit for audible noise reduction 12 3 4 87 6 5 hv857 el lamp on = v dd off = 0v enable l x c s + - v in c in d r el r sw + - v dd c dd r ser vddrsw-osc rel-osc gnd vavb cs lx downloaded from: http:///
7 supertex inc. www.supertex.com doc.# dsfp-hv857 a062013 hv857 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 wave - form that is quieter than a sine wave. the waveform takes the shape of approximately 2rc time constants for rising and 2rc time constants for falling, where c is the capaci - tance 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. 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 per - formance 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. effect of series resistor on el lamp audible noise and brightness as el lamp ages, its brightness is reduced and its capaci - tance 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 lamps half-life (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. downloaded from: http:///
8 supertex inc. www.supertex.com doc.# dsfp-hv857 a062013 hv857 8-lead dfn package outline (k7) 3.00x3.00mm body, 0.80mm height (max), 0.65mm pitch symbol a a1 a3 b d d2 e e2 e l l1 dimension (mm) min 0.70 0.00 0.20 ref 0.25 2.85* 1.60 2.85* 1.35 0.65 bsc 0.30 0.00* 0 o nom 0.75 0.02 0.30 3.00 - 3.00 - 0.40 - - max 0.80 0.05 0.35 3.15* 2.50 3.15* 1.75 0.50 0.15 14 o jedec registration mo-229, variation weec-2, issue c, aug. 2003. * this dimension is not speciied in the jedec drawing. drawings not to scale. supertex doc. #: dspd-8dfnk73x3p065, version c081109. seating plane top vi ew bottom view a a1 d e d2 e2 a3 l l1 view b note 1 (index area d/2 x e/2) note 3 note 2 note 1 (index area d/2 x e/2) 1 1 8 8 e side view vi ew b notes: 1. a pin 1 identiier must be located in the index area indicated. the pin 1 identiier can be: a molded mark/identiier; an embedded metal marker; or a printed indicator. 2. depending on the method of manufacturing, a maximum of 0.15mm pullback (l1) may be present. 3. the inner tip of the lead may be either rounded or square. downloaded from: http:///
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 liabilit y 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) ?2013 supertex inc. all rights reserved. unauthorized use or reproduction is prohibited. supertex inc. 1235 bordeaux drive, sunnyvale, ca 94089 t el: 408-222-8888 www.supertex.co m 9 hv857 (the package drawing(s) in this data sheet may not relect the most current speciications. for the latest package outline information go to http://www.supertex.com/packaging.html .) doc.# dsfp-hv857 a062013 8-lead msop package outline (mg) 3.00x3.00mm body, 1.10mm height (max), 0.65mm pitch view b vi ew a-a seating plane gauge plane l l1 l2 vi ew b 1 1 8 e e1 d e b a a2 a1 seating plane a a top vi ew side view note 1 (index area d/2 x e1/2) symbol a a1 a2 b d e e1 e l l1 l2 1 dimension (mm) min 0.75* 0.00 0.75 0.22 2.80* 4.65* 2.80* 0.65 bsc 0.40 0.95 ref 0.25 bsc 0 o 5 o nom - - 0.85 - 3.00 4.90 3.00 0.60 - - max 1.10 0.15 0.95 0.38 3.20* 5.15* 3.20* 0.80 8 o 15 o jedec registration mo-187, variation aa, issue e, dec. 2004. * this dimension is not speciied in the jedec drawing. drawings are not to scale. supertex doc. #: dspd-8msopmg, version h041309. note: 1. a pin 1 identiier must be located in the index area indicated. the pin 1 identiier can be: a molded mark/identiier; an embedded metal marker; or a printed indicator. downloaded from: http:///
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