hv9922 1235 bordeaux drive, sunnyvale, ca 94089 t el: 408-222-8888 www .supertex.com features constant output current: 50ma universal 85-264vac operation fixed off-time buck converter internal 475v power mosfet applications decorative lighting low power lighting ?xtures ? ? ? ? ? ? general description the hv9922 is a pulse width modulated (pwm) high- ef?ciency led driver control ic. it allows ef?cient operation of led strings from voltage sources ranging up to 400vdc. the hv9922 includes an internal high voltage switching mosfet controlled with ?xed off-time (t off ) of approximately 10.5s. the led string is driven at constant current, thus providing constant light output and enhanced reliability. the output current is internally ?xed at 50ma for hv9922. the peak current control scheme provides good regulation of the output current throughout the universal ac line voltage range of 85 to 264vac or dc input voltage of 20 to 400v. typical application circuit hv9922 vdd drai n gnd 3-pin switch-mode led lamp driver ic
2 hv9922 1235 bordeaux drive, sunnyvale, ca 94089 t el: 408-222-8888 www .supertex.com sym parameter min typ max units conditions regulator (v dd ) v dd v dd regulator output - - - 7.5 - v --- v drain v drain supply voltage - - 20 - - v --- v uvlo v dd undervoltage threshold - - 5.0 - - v --- ?v uvlo v dd undervoltage lockout hysteresis - - - 200 - mv --- i dd operating supply current - - - 200 350 a v dd(ext) = 8.5v, v drain = 40v output (drain) v br breakdown voltage * - 475 - - v --- r on on-resistance - - - - 210 i drain = 50ma c drain output capacitance - # - 1.0 5.0 pf v drain = 400v i sat mosfet saturation current - # 100 150 - ma --- current sense comparator i th threshold current * - 49 - 63 ma --- t blank leading edge blanking delay * # 200 300 400 ns --- t on(min) minimum on-time - - - - 650 ns --- off-time generator t off off-time - - 8.0 10.5 13 s --- note: * denotes the speci?cations which apply over the full operating ambient temperature range of -40 c < t a < +85 c. # denotes guaranteed by design. ordering information device package options to-92 sot-89 hv9922 hv9922n3-g HV9922N8-G absolute maximum ratings parameter value supply voltage, v dd -0.3 to +10v supply current, i dd +5.0ma operating ambient temperature range -40c to +85c operating junction temperature range -40 to +125c storage temperature range -65 to +150c power dissipation @ 25c, to-92 740mw power dissipation @ 25c, sot-89 1600mw * stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. these are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the speci?cations is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. * mounted on fr4 board, 25mm x 25mm x 1.57mm. electrical characteristics (speci?cations are at t a = 25 c and v drain = 50v, unless otherwise noted.) -g indicates package is rohs compliant (green) gnd vdd drain pin con?gurations to-92 (n3) sot-89 (n8) gnd vd d drain product marking to-92 (n3) sot-89 (n8) w = code for week sealed y = code for year sealed = green packagin g h22yw yy = year sealed ww = week sealed = green packaging h v 9 9 2 2 y y w w
3 hv9922 1235 bordeaux drive, sunnyvale, ca 94089 t el: 408-222-8888 www .supertex.com typical performance characteristics (t j = 25 c unless otherwise noted) 0 20 40 60 80 10 0 12 0 14 0 16 0 18 0 20 0 -4 0 - 15 10 35 60 85 11 0 ju nc ti on te m p er at ur e, c on resist an ce, oh m 49 0 50 0 51 0 52 0 53 0 54 0 55 0 56 0 57 0 58 0 -4 0 - 15 10 35 60 85 110 j unc ti on te m p er at ur e, c drain br eakd ow n vo lt ag e, v 0 20 40 60 80 10 0 12 0 14 0 16 0 18 0 0 1 0 2 0 3 0 4 0 dra in vo lt ag e, v drain cu rre nt , ma 0 2 4 6 8 10 12 -4 0 - 15 10 35 60 85 11 0 ju nc ti on te m p er at ur e, c of f ti me , us 1 10 10 0 1000 0 1 0 2 0 3 0 4 0 drai n vo lt ag e, v drai n ca pa ci tan ce ( pf) j = 25c t j = 125c 0. 8 0.85 0. 9 0.95 1 1.05 1. 1 -4 0 - 15 10 35 60 85 110 junction temperature, c no rm al iz ed th re sh ol d cu rr en t t
4 hv9922 1235 bordeaux drive, sunnyvale, ca 94089 t el: 408-222-8888 www .supertex.com the hv9922 is a pwm peak current controller for controlling a buck converter topology in continuous conduction mode (ccm). the output current is internally preset at 50ma. when the input voltage of 20 to 400v appears at the drain pin, the internal high-voltage linear regulator seeks to maintain a voltage of 7.5vdc at the vdd pin. until this voltage exceeds the internally programmed under-voltage threshold, the output switching mosfet is non-conductive. when the threshold is exceeded, the mosfet turns on. the input current begins to ?ow into the drain pin. hysteresis is provided in the under-voltage comparator to prevent oscillation. when the input current exceeds the internal preset level, a current sense comparator resets an rs ?ip-?op, and the mosfet turns off. at the same time, a one-shot circuit is activated that determines the duration of the off-state (10.5s typ.). as soon as this time is over, the ?ip-?op sets again. the new switching cycle begins. a blanking delay of 300ns is provided that prevents false triggering of the current sense comparator due to the leading edge spike caused by circuit parasitics. application information the hv9922 is a low-cost off-line buck converter ic speci?cally designed for driving multi-led strings. it can be operated from either universal ac line range of 85 to 264vac, or 20 to 400vdc, and drives up to tens of high brightness leds. all leds can be run in series, and the hv9922 regulates at constant current, yielding uniform illumination. the hv9922 is compatible with triac dimmers. the output current is internally ?xed at 50ma. this part is available in space saving to-92 and sot-89 packages. selecting l1 and d1 there is a certain trade-off to be considered between optimal sizing of the output inductor l1 and the tolerated output current ripple. the required value of l1 is inversely proportional to the ripple current ?i o in it. l1 = (v o ? t off ) / i o (1) v o is the forward voltage of the led string. t off is the off- time of the hv9922. the output current in the led string (i o ) is calculated then as: i o = i th - (i o / 2) (2) where i th is the current sense comparator threshold. the ripple current introduces a peak-to-average error in the output current setting that needs to be accounted for. due to the constant off-time control technique used in the hv9922, the ripple current is independent of the input ac or dc line voltage variation. therefore, the output current will remain unaffected by the varying input voltage. adding a ?lter capacitor across the led string can reduce the output current ripple even further, thus permitting a reduced value of l1. however, one must keep in mind that the peak-to-average current error is affected by the variation of t off . therefore, the initial output current accuracy might be sacri?ced at large ripple current in l1. another important aspect of designing an led driver with the hv9922 is related to certain parasitic elements of the circuit, including distributed coil capacitance of l1, junction capacitance and reverse recovery of the recti?er diode d1, capacitance of the printed circuit board traces c pcb and output capacitance c drain of the controller itself. these parasitic elements affect the ef?ciency of the switching converter and could potentially cause false triggering of the current sense comparator if not properly managed. minimizing these parasitics is essential for ef?cient and reliable operation of the hv9922. coil capacitance of inductors is typically provided in the manufacturers data books either directly or in terms of the self-resonant frequency (srf). srf = 1 / (2 (l ? c l )) where l is the inductance value, and c l is the coil capacitance.) charging and discharging this capacitance every switching cycle causes high-current spikes in the led string. therefore, connecting a small capacitor c o (~10nf) is recommended to bypass these spikes. using an ultra-fast recti?er diode for d1 is recommended to achieve high ef?ciency and reduce the risk of false triggering of the current sense comparator. using diodes with shorter reverse recovery time t rr and lower junction capacitance c j achieves better performance. the reverse voltage rating v r of the diode must be greater than the maximum input voltage of the led lamp. the total parasitic capacitance present at the drain pin of the hv9922 can be calculated as: c p = c drain + c pcb +c l +c j (3) functional description
5 hv9922 1235 bordeaux drive, sunnyvale, ca 94089 t el: 408-222-8888 www .supertex.com when the switching mosfet turns on, the capacitance c p is discharged into the drain pin of the ic. the discharge current is limited to about 150ma typically. however, it may become lower at increased junction temperature. the duration of the leading edge current spike can be estimated as: t spike = ((v in ? c p ) / (i sat )) +t r (4) in order to avoid false triggering of the current sense comparator, c p must be minimized in accordance with the following expression: (5) where t blank(min) is the minimum blanking time of 200ns, and v in(max) is the maximum instantaneous input voltage. estimating power loss discharging the parasitic capacitance c p into the drain pin of the hv9922 is responsible for the bulk of the switching power loss. it can be estimated using the following equation: (6) where f s is the switching frequency, i sat is the saturated drain current of the hv9922. the switching loss is the greatest at the maximum input voltage. the switching frequency is given by the following: f s = (v in - -1 ? v o ) / v in ? t off (7) where is the ef?ciency of the power converter. when the hv9922 led driver is powered from the full-wave recti?ed ac input, the switching power loss can be estimated as: (8) v ac is the input ac line voltage. the switching power loss associated with turn-off transitions of the drain pin can be disregarded. due to the large amount of parasitic capacitance connected to this switching node, the turn-off transition occurs essentially at zero-voltage. conduction power loss in the hv9922 can be calculated as: p cond = (d ? i o 2 ? r on ) + (i dd ? v in ? (1 - d)) (9) where d = v o /v in is the duty ratio, r on is the on-resistance, i dd is the internal linear regulator current. when the led driver is powered from the full-wave recti?ed ac line input, the exact equation for calculating the conduction loss is more cumbersome. however, it can be estimated using the following equation: p cond = (k c ? i o 2 ? r on ) + (k d ? i dd ? v ac ) (10) where v ac is the input ac line voltage. the coef?cients k c and k d can be determined from the minimum duty ratio of the hv9922. fig. 1. conduction loss coef?cients k c and k d emi filter as with all off-line converters, selecting an input ?lter is critical to obtaining good emi. a switching side capacitor, albeit of small value, is necessary in order to ensure low impedance to the high frequency switching currents of the converter. as a rule of thumb, this capacitor should be approximately 0.1- 0.2 f/w of led output power. a recommended input ?lter is shown in figure 2 for the following design example. design example let us design an hv9922 led lamp driver meeting the following speci?cations: input: universal ac, 85 - 135vac output current: 50ma load: string of 12 led (power topled osram ? v f = 2.5v max. each) ( ) ( ) ( ) sat blank min rr p in max i t t c v ? ? < 2 in p switch in sat rr s v c p v i t f 2 ? ? = + ? ? ? ? ? ? 0 0 .1 0. 2 0 .3 0. 4 0 .5 0. 6 0 .7 0. 1 0. 2 0. 3 0. 4 0. 5 0. 6 0. 7 kd dm ( ) kc dm ( ) dm ( ) ( ) 1 switch ac p sat rr ac o off 1 p v c 2 i t v v 2 t ? ? + ? ? ? ? ?
6 hv9922 1235 bordeaux drive, sunnyvale, ca 94089 t el: 408-222-8888 www .supertex.com step 1. calculating l1. the output voltage v o = 12 x v f = 30v (max.). use equation (1) assuming a 30% peak-to-peak ripple. l1 = (30v ? 10.5s) / (0.3 ? 50ma) = 21mh select l1 22mh, i = 60ma. typical srf = 270khz. calculate the coil capacitance. step 2. selecting d1 select d1 mur160 with v r = 600v, t rr 50ns and c j 8pf (v f > 50v). step 3. calculating total parasitic capacitance using (3) c p = 5pf + 5pf + 15pf + 8pf = 33pf step 4. calculating the leading edge spike duration using (4), (5) step 5. estimating power dissipation in hv9922 at 135vac using (8) and (10) let us assume that the overall ef?ciency = 0.7. switching power loss: p switch 65mw minimum duty ratio: d m = 30v / (0.7 ? 135v ? 2) 0.23 conduction power loss: p cond = 32 ? (50ma) 2 ? 200 + 0.62 ? 200a ? 135v p cond 175mw total power dissipation in hv9922: p total = 65mw + 175mw = 240mw step 6. selecting input capacitor c in output power = 30v ? 50ma = 1.5w select c in 0.22f, 250v. c l = 1 = 1 15pf l1 x (2 x srf ) 2 22mh x ( 2 x 270khz) 2 t spike = 135v x 2 x 33pf + 50ns 1 13ns < t blank(min) 100m a p switch = 1 (135v x 33pf + 2 x 100m a x 50ns) 2 x 10.5s 135v - 30v 0.7 ( ) figure 2. universal 85-264vac led lamp driver c in ac line 85-264v c dd 1 3 2 hv9922 d1 l1 le d 1 -l ed 12 d2 u1 d3 d4 d5 c in 2 l in vrd1 f1 c o vdd drain gnd
7 hv9922 1235 bordeaux drive, sunnyvale, ca 94089 t el: 408-222-8888 www .supertex.com 62 .0 0 64 .0 0 66 .0 0 68 .0 0 70 .0 0 72 .0 0 74 .0 0 76 .0 0 78 .0 0 80 .0 0 82 .0 0 75 100 125 15 0 1 75 20 0 2 25 250 275 in pu t ac li ne vo lt ag e (v ac) e ffi ci en cy (% ) figure 3. ty pi cal effi ci enc y ze ro volt ag e tr an si ti on figure 4. sw it ch-off tr ansitio n. ch 1: v drain , ch 3: i dra in 25 ma le ad in g ed ge sp ik e sw it ch off figure 5. ty pi cal effi ci enc y figure 6. sw it ch-off tr ansitio n. ch 1: v drain , ch 3: i dra in 62 .0 0 64 .0 0 66 .0 0 68 .0 0 70 .0 0 72 .0 0 74 .0 0 76 .0 0 78 .0 0 80 .0 0 82 .0 0 75 100 125 15 0 1 75 20 0 2 25 250 275 in pu t ac li ne vo lt ag e (v ac) e ffi ci en cy (% ) figure 3. ty pi cal effi ci enc y ze ro volt ag e tr an si ti on figure 4. sw it ch-off tr ansitio n. ch 1: v drain , ch 3: i dra in 25 ma le ad in g ed ge sp ik e sw it ch off figure 5. ty pi cal effi ci enc y figure 6. sw it ch-off tr ansitio n. ch 1: v drain , ch 3: i dra in functional block diagram vd d re f + - r drain gn d hv9922 s r q q regulator 7.5v t off = 10.5s t blank = 300ns
8 hv9922 1235 bordeaux drive, sunnyvale, ca 94089 t el: 408-222-8888 www .supertex.com see figure 7 for a recommended circuit board layout for the hv9922. single point grounding use a single point ground connection from the input ?lter capacitor to the area of copper connected to the gnd pin. bypass capacitor (c dd ) the vdd pin bypass capacitor c dd should be located as near as possible to the vdd and gnd pins. switching loop areas the area of the switching loop connecting the input ?lter capacitor c in , the diode d1 and the hv9922 together should be kept as small as possible. the switching loop area connecting the output ?lter capacitor c o , the inductor l1 and the diode d1 together should be kept as small as possible. thermal considerations vs. radiated emi the copper area where gnd pin is connected acts not only as a single point ground, but also as a heat sink. this area should be maximized for good heat sinking, especially when hv9922n8, (sot-89 package), is used. the same applies to the cathode of the free-wheeling diode d1. both nodes are quiet and therefore, will not cause radiated rf emission. the switching node copper area connected to the drain pin of the hv9922, the anode of d1 and the inductor l1 needs to be minimized. a large switching node area can increase high frequency radiated emi. input filter layout considerations the input circuits of the emi ?lter must not be placed in the direct proximity to the inductor l1 in order to avoid magnetic coupling of its leakage ?elds. this consideration is especially important when unshielded construction of l1 is used. when an axial input emi ?lter inductor l in is selected, it must be positioned orthogonal with respect to l1. the loop area formed by c in2 , l in and c in should be minimized. the input lead wires must be twisted together. hv9922 layout considerations pin # function description 1 drain drain terminal of the output switching mosfet and a linear regulator input. 2 gnd common connection for all circuits. 3 vdd power supply pin for internal control circuits. bypass this pin with a 0.1uf low impedance capacitor . pin description figure 7. recommended circuit board layout with the hv9922n3 d2-5 l in c o l1 u1 vrd1 c in c in 2 d1 c dd f1 ac line 85-264vac led + led - co mp onent side view
9 hv9922 1235 bordeaux drive, sunnyvale, ca 94089 t el: 408-222-8888 www .supertex.com 3-lead to-92 package outline (n3) symbol a b c d e e1 e e1 l dimensions (inches) min .170 .014 ? .014 ? .175 .125 .080 .095 .045 .500 nom - - - - - - - - - max .210 .022 ? .022 ? .205 .165 .105 .105 .055 .610* jedec registration to-92. * this dimension is not speci?ed in the original jedec drawing. the value listed is for reference only. ? this dimension is a non-jedec dimension. drawings not to scale. supertex doc.#: dspd-3to92n3, version d080408. seating plane 1 2 3 front v iew side v iew bottom v iew e1 e d e1 l e c 1 2 3 b a
supertex inc. does not recommend the use of its products in life support applications, and will not knowingly sell them for use in such appl ications 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 . ?2008 all rights reserved. unauthorized use or reproduction is prohibited . 1235 bordeaux drive, sunnyvale, ca 9408 9 te l: 408-222-8888 www .supertex.com 10 hv9922 (the package drawing(s) in this data sheet may not re?ect the most current speci?cations. for the latest package outline information go to http://www.supertex.com/packaging.htm l .) dsfp# hv9922 b091208 3-lead to-243aa (sot-89) package outline (n8) symbol a b b1 c d d1 e e1 e e1 h l dimensions (mm) min 1.40 0.44 0.36 0.35 4.40 1.62 2.29 2.13 1.50 bsc 3.00 bsc 3.94 0.89 nom - - - - - - - - - - max 1.60 0.56 0.48 0.44 4.60 1.83 2.60 2.29 4.25 1.20 jedec registration to-243, variation aa, issue c, july 1986. drawings not to scale . supertex doc. #: dspd-3to243aan8, version d070908. b b1
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