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february 2012 figure 1. typical standby application. order part number 85-265 vac 230 vac or 115 vac w/doubler product highlights lowest cost, low power switcher solution ? lower cost than rcc, discrete pwm and other integrat - ed/hybrid solutions ? cost effective replacement for bulky linear adapters ? lowest component count ? simple on/off control C no loop compensation devices ? no bias winding C simpler, lower cost transformer ? allows simple rc type emi flter for up to 2 w from universal input or 4 w from 115 vac input extremely energy effcient ? consumes only 30/60 mw at 115/230 vac with no load ? meets blue angel, energy star, energy 2000 and 200 mw european cell phone requirements for standby ? saves $1 to $4 per year in energy costs (at $0.12/kwhr) compared to bulky linear adapters ? ideal for cellular phone chargers, standby power supplies for pc, tv and vcr, utility meters, and cordless phones. high performance at low cost ? high-voltage powered C ideal for charger applications ? very high loop bandwidth provides excellent transient response and fast turn on with practically no overshoot ? current limit operation rejects line frequency ripple ? glitch free output when input is removed ? built-in current limit and thermal protection ? 44 khz operation (tny253/4) with snubber clamp reduces emi and video noise in tvs and vcrs ? operates with optocoupler or bias winding feedback description the tinyswitch family uses a breakthrough design to provide the lowest cost, high effciency, off-line switcher solution in the 0 to 10 w range. these devices integrate a 700 v power mosfet, oscillator, high-voltage switched current source, current limit and thermal shutdown circuitry. they start-up and run on power derived from the drain voltage, eliminat - ing the need for a transformer bias winding and the associated circuitry. and yet, they consume only about 80 mw at no load, from 265 vac input. a simple on/off control scheme also eliminates the need for loop compensation. tny253p tny254p tinyswitch selection guide package dip-8 dip-8 smd-8 smd-8 tny253g tny255p 0-2 w 1-4 w 0-4 w 2-5 w tny255g dip-8 tny254g smd-8 3.5-6.5 w 4-10 w the tny253 and tny254 switch at 44 khz to minimize emi and to allow a simple snubber clamp to limit drain spike voltage. at the same time, they allow use of low cost ee16 core transformers to deliver up to 5 w. the tny253 is identical to tny254 except for its lower current limit, which reduces output short-circuit current for applications under 2.5 w. tny255 uses higher switching rate of 130 khz to deliver up to 10 w from the same low cost ee16 core for applications such as pc standby supply. an ee13 or ef13 core with safety spaced bobbin can be used for applications under 2.5 w. absence of a bias winding eliminates the need for taping/margins in most applications, when triple insulated wire is used for the secondary. this simplifes the transformer construction and reduces cost. pi-2178-022699 wide-range high-voltage dc input tinyswitch d s en bp + ? + ? dc output table 1. *please refer to the key application considerations section for details. recommended range for lowest system cost* tny253/254/255 tinyswitch ? family energy effcient, low power off-line switchers
rev e 02/12 tny253/254/255 2 figure 2. functional block diagram. figure 3. pin confguration. pin functional description drain (d) pin: 3rhu 02)( gudl frhfwlr 3urylghv lwhudo rshudwl fuuhwiruerwvwduwsdgvwhdgvwdwhrshudwlr bypass (bp) pin: rhfwlr srlw iru d hwhudo esdvv fdsdflwru iru wh lwhu - doo hhudwhg vsso sdvv sl lv rw lwhghg iru vruflvssofuuhwwrhwhudo fluflwu enable (en) pin: h srhu 02)( vlwfl fd eh whupldwhg e sool wlv sl or h fdudfwhulvwlf ri wlv sl lv htlydohw wr d yrowdh vrufh ri dssurlpdwho lw d vrufh fuuhw fodpsri source (s) pin: 3rhu02)( vrufhfrhfwlr3ulpduuhwu tinyswitch functional description 7l6lwfk lv lwhghg iru or srhu riiolh dssolfdwlrv ,w frpelhv d klkyrowdh srhu 026)(7 vlwfk lwk d srhu vxsso frwuroohu l rh ghylfh 8olnh d fryhwlrdo 3:0 3xovh :lgwk 0rgxodwru frwuroohu wkh 7l6lwfk xvhv d vlpsoh212))frwurowruhxodwhwkhrxwsxwyrowdh 7kh tinyswitch frwuroohu frvlvwv r d 2vfloodwru deoh 6hvh dg rlf fluflw 9 5hodwru 8ghuyrowdh fluflw vwhuhwlf 2yhu 7hpshudwuh 3urwhfwlr uuhw lplw fluflw hdgl gh odnl dg d 9 srhu 0267 luh vkrv d fwlrdo eorfn gldudp lwk wkh prvw lpsruwdw hdwuhv oscillator h rvfloodwru iuhthf lv lwhudoo vhw dw n n iru wh 1 h wr vldov ri lwhuhvw duh wh 0dl - pp w foh vldo 0 lf uv dw wslfdoo gw ffoh dg wh orfn vldo wdw lglfdwhv wh ehll ri hdf ffoh :h ffohv duh vnlsshg vhh ehor wh rvflood - wru iuhthf greohv hfhsw iru 1 lf uhpdlv dw n lv lfuhdvhv wh vdpsol udwh dw wh (1/( sliruidvwhuorrsuhvsrvh enable (sense and logic) h (1/( sl fluflw dv d vrufh iroorhu lsw vwdh vhw dw h lsw fuuhw lv fodpshg e d fuuhw vrufh vhw dw pi-2197-061898 clock oscillator 5.8 v 5.1 v source s r q dc max bypass + - v i limit leading edge blanking thermal shutdown + - drain regulator 5.8 v undervoltage 1.5 v + v th enable q 50 a pi-2199-031501 enable 8 5 7 6 drain source source source 1 4 2 3 source source bypass p package (dip-8 ) g package (smd-8)
tny253/254/255 3 rev e 02/12 circuit is sampled at the rising edge of the oscillator clock signal (at the beginning of each cycle). if it is high, then the power mosfet is turned on (enabled) for that cycle, otherwise the power mosfet remains in the off state (cycle skipped). since the sampling is done only once at the beginning of each cycle, any subsequent changes at the enable pin during the cycle are ignored. 5.8 v regulator the 5.8 v regulator charges the bypass capacitor connected to the bypass pin to 5.8 v by drawing a current from the voltage on the drain, whenever the mosfet is off. the bypass pin is the internal supply voltage node for the tinyswitch. when the mosfet is on, the tinyswitch runs off of the energy stored in the bypass capacitor. extremely low power consumption of the internal circuitry allows the tinyswitch to operate continu - ously from the current drawn from the drain pin. a bypass capacitor value of 0.1 f is suffcient for both high frequency de-coupling and energy storage. undervoltage the undervoltage circuitry disables the power mosfet when the bypass pin voltage drops below 5.1 v. once the bypass pin voltage drops below 5.1 v, it has to rise back to 5.8 v to enable (turn-on) the power mosfet. hysteretic over temperature protection the thermal shutdown circuitry senses the die junction tem - perature. the threshold is set at 135 c with 70 c hysteresis. when the junction temperature rises above this threshold (135 c) the power mosfet is disabled and remains disabled until the die junction temperature falls by 70 c, at which point it is re-enabled. current limit the current limit circuit senses the current in the power mosfet. when this current exceeds the internal threshold (i limit ), the power mosfet is turned off for the remainder of that cycle. the leading edge blanking circuit inhibits the current limit comparator for a short time (t leb ) after the power mosfet is turned on. this leading edge blanking time has been set so that current spikes caused by primary-side capacitance and secondary-side rectifer reverse recovery time will not cause premature termination of the switching pulse. tinyswitch operation tinyswitch is intended to operate in the current limit mode. when enabled, the oscillator turns the power mosfet on at the beginning of each cycle. the mosfet is turned off when the current ramps up to the current limit. the maximum on-time of the mosfet is limited to dc max by the oscillator. since the current limit and frequency of a given tinyswitch device are constant, the power delivered is proportional to the primary inductance of the transformer and is relatively independent of the input voltage. therefore, the design of the power supply involves calculating the primary inductance of the transformer for the maximum power required. as long as the tinyswitch device chosen is rated for the power level at the lowest input voltage, the calculated inductance will ramp up the current to the current limit before the dc max limit is reached. enable function the tinyswitch senses the enable pin to determine whether or not to proceed with the next switch cycle as described earlier. once a cycle is started tinyswitch always completes the cycle (even when the enable pin changes state half way through the cycle). this operation results in a power supply whose output voltage ripple is determined by the output capacitor, amount of energy per switch cycle and the delay of the enable feedback. the enable signal is generated on the secondary by comparing the power supply output voltage with a reference voltage. the enable signal is high when the power supply output voltage is less than the reference voltage. in a typical implementation, the enable pin is driven by an optocoupler. the collector of the optocoupler transistor is connected to the enable pin and the emitter is connected to the source pin. the optocoupler led is connected in series with a zener across the dc output voltage to be regulated. when the output voltage exceeds the target regulation voltage level (optocoupler diode voltage drop plus zener voltage), the optocoupler diode will start to conduct, pulling the enable pin low. the zener could be replaced by a tl431 device for improved accuracy. the enable pin pull-down current threshold is nominally 50 a, but is set to 40 a the instant the threshold is exceeded. this is reset to 50 a when the enable pull-down current drops below the current threshold of 40 a. on/off control the internal clock of the tinyswitch runs all the time. at the beginning of each clock cycle the tinyswitch samples the enable pin to decide whether or not to implement a switch cycle. if the enable pin is high (< 40 a), then a switching cycle takes place. if the enable pin is low (greater than 50 a) then no switching cycle occurs, and the enable pin status is sampled again at the start of the subsequent clock cycle. at full load tinyswitch will conduct during the majority of its clock cycles (figure 4). at loads less than full load, the tinyswitch will skip more cycles in order to maintain volt - age regulation at the secondary output (figure 5). at light load or no load, almost all cycles will be skipped (figure 6). a small percentage of cycles will conduct to support the power consumption of the power supply.
rev e 02/12 tny253/254/255 4 figure 4. tinyswitch operation at heavy load. figure 5. tinyswitch operation at medium load. v drain v en clock dc drain i max pi-2255-061298 v drain v en clock dc drain i max pi-2259-061298 the response time of tinyswitch on/off control scheme is very fast compared to normal pwm control. this provides high line ripple rejection and excellent transient response. power up/down tinyswitch requires only a 0.1 f capacitor on the bypass pin. because of the small size of this capacitor, the power-up delay is kept to an absolute minimum, typically 0.3 ms (fig ure 7). due to the fast nature of the on/off feedback, there is no overshoot at the power supply output. during power-down, the power mosfet will switch until the rectifed line voltage drops to approximately 12 v. the power mosfet will then remain off without any glitches (figure 8). bias winding eliminated tinyswitch does not require a bias winding to provide power to the chip. instead it draws the power directly from the drain pin (see functional description above). this has two main benefts. first for a nominal application, this eliminates the cost of an extra bias winding and associated components. secondly, for charger applications, the current-voltage char acteristic often allows the output voltage to fall to low values while still delivering power. this type of application normally requires a forward-bias winding which has many more associ ated components, none of which are necessary with tinyswitch. current limit operation each switching cycle is terminated when the drain current reaches the current limit of the tinyswitch. for a given primary inductance and input voltage, the duty cycle is constant. how ever, duty cycle does change inversely with the input voltage providing voltage feed-forward advantages: good line ripple rejection and relatively constant power delivery independent of the input voltage. 44 khz switching frequency (tny253/254) switching frequency (with no cycle skipping) is set at 44 khz. this provides several advantages. at higher switching frequen cies, the capacitive switching losses are a signifcant proportion of the power losses in a power supply. at higher frequencies, the preferred snubbing schemes are rcd or diode-zener clamps. however, due to the lower switching frequency of tinyswitch , it is possible to use a simple rc snubber (and even just a capaci tor alone in 115 vac applications at powers levels below 4 w). secondly, a low switching frequency also reduces emi fltering requirements. at 44 khz, the frst, second and third harmon ics are all below 150 khz where the emi limits are not very restrictive. for power levels below 4 w it is possible to meet worldwide emi requirements with only resistive and capaci tive flter elements (no inductors or chokes). this signifcantly reduces emi flter costs. finally, if the application requires stringent noise emissions (such as video applications), then the tny253/254 will allow more effective use of diode snubbing (and other secondary snubbing techniques). the lower switching frequency allows rc snubbers to be used to reduce noise, without signifcantly impacting the effciency of the supply. 130 khz switching frequency (tny255) the switching frequency (with no cycle skipping) is set at 130 khz. this allows the tny255 to deliver 10 w while still using the same size, low cost transformer (ee16) as used by the tny253/254 for lower power applications.
tny253/254/255 5 rev e 02/12 figure 6. tinyswitch operation at light load. figure 7. tinyswitch power-up timing diagram. figure 8. tinyswitch power down timing diagram. pi-2261-061198 v drain v en clock dc drain i max bypass pin capacitor the bypass pin uses a small 0.1 f ceramic capacitor for decoupling the internal power supply of the tinyswitch. application examples television standby tinyswitch is an ideal solution for low cost, high effciency standby power supplies used in consumer electronic products such as tvs. figure 9 shows a 7.5 v, 1.3 w fyback circuit that uses tny253 for implementing a tv standby supply. the circuit operates from the dc high-voltage already available from the main power supply. this input voltage can range from 120 to 375 vdc depending on the input ac voltage range that the tv is rated for. capacitor c1 flters the high-voltage dc supply, and is necessary only if there is a long trace length from the source of the dc supply to the inputs of the tv standby circuit. the high-voltage dc bus is applied to the series combination of the primary winding of t1 and the integrated high-voltage mosfet inside the tny253. the low operating frequency of the tny253 (44 khz), allows a low cost snubber circuit c2 and r1 to be used in place of a primary clamp circuit. in addition to limiting the drain turn off voltage spike to a safe value, the rc snubber also reduces radiated video noise by lowering the dv/dt of the drain waveform, which is critical for video applications such as tv and vcr. on fxed frequency pwm and rcc circuits, use of a snubber will result in an undesir able fxed ac switching loss that is independent of load. the on/off control on the tinyswitch eliminates this problem by scaling the effective switching frequency and therefore, switching loss linearly with load. thus the effciency of the supply stays relatively constant down to a fraction of a watt of output loading. the secondary winding is rectifed and fltered by d1 and c4 to create the 7.5 v output. l1 and c5 provide additional fltering. the output voltage is determined by the sum of the optocoupler u2 led forward drop (~ 1 v) and zener diode vr1 voltage. the resistor r2, maintains a bias current through the zener to improve its voltage tolerance. 10 w standby the tny255 is ideal for standby applications that require up to 10 w of power from 230 vac or 100/115 vac with doubler circuit. the tny255 operates at 130 khz as opposed to 44 khz for tny253/254. the higher frequency operation allows the v drain v in pi?2253-062398 0. 2 time (ms) .4 .6 .8 1 0 v 0 v v drain v in 12 v pi?2251-062398 12 v 0 100 time (ms) 200 300 400 500 0 v 0 v
rev e 02/12 tny253/254/255 6 figure 9. 1.3 w tv standby circuit using tny253. figure 10. 10 w standby supply circuit. use of a low cost ee16 core transformer up to the 10 w level. figure 10 shows a 5 v, 10 w circuit for such an application. the circuit operates from the high-voltage dc supply already available from the main power supply. capacitor c1 flters the high-voltage dc supply, and is necessary only if there is a long trace length from the source of the dc supply to the inputs of the standby circuit. the high-voltage dc bus is applied to the primary winding of t1 in series with the integrated high-voltage mosfet inside the tny255. the diode d1, capacitor c2 and resistor r1 comprise the clamp circuit that limits the turn-off voltage spike on the tinyswitch drain pin to a safe value. the secondary winding is rectifed and fltered by d2 and c4 to provide the 5 v ouput. additional fltering is provided by l1 and c5. the output voltage is determined by the sum of the optocoupler u2 led forward drop (~ 1 v) and zener diode vr1 voltage. the resistor r2, maintains a bias current through the zener to improve its voltage tolerance. for tighter tolerance, a tl431 precision reference ic feedback circuit may be used. cellular phone charger the tinyswitch is well suited for applications that require a constant voltage and constant current output. tinyswitch is always powered from the input high-voltage, therefore it does not require bias winding for power. consequently, its opera - tion is not dependent on the level of the output voltage. this allows for constant current charger designs that work down to zero volts on the output. pi-2242-082898 tinyswitch d s en bp + 5 v rtn c1 0.01 f 1 kv c3 0.1 f 240 - 375 vdc r1 150 k 1 w u2 ltv817 d2 sb540 l1 10 h c4 2700 f 6.3 v c5 220 f 10 v vr1 1n5229b u1 tny255p c2 4700 pf 1 kv t1 1 4 8 10 r2 68 d1 1n4937 optional pi-2246-082898 dc in 120 - 375 vdc tinyswitch d s en bp + ? + 7.5 v rtn c3 0.1 f r2 1 k vr1 1n5235b c1 0.01 f 1 kv r1 100 1/2 w c2 56 pf 1 kv d1 1n4934 l1 15 h c5 47 f 10 v c4 330 f 10 v u1 tny253p t1 u2 sfh615-2 c6 680 pf y1 safety 1 4 8 10 optional
tny253/254/255 7 rev e 02/12 figure 11. 3.6 w constant voltage-constant current cellular phone charger circuit. figure 11 shows a 5.2 v, 3.6 w cellular phone charger circuit that uses the tny254 and provides constant voltage and constant current output over an universal input (85 to 265 vac) range. the ac input is rectifed and fltered by d1 - d4, c1 and c2 to create a high-voltage dc bus connected to t1 in series with the high-voltage mosfet inside the tny254. the inductor l1 forms a -flter in conjunction with c1 and c2. the resistor r1 damps resonances in the inductor l1. the low frequency of operation of tny254 (44 khz) allows use of the simple -flter described above in combination with a single y1-capacitor c8 to meet worldwide conducted emi standards. the diode d6, capacitor c4 and resistor r2 comprise the clamp circuit that limits the turn-off voltage spike on the tinyswitch drain pin to a safe value. the secondary winding is rectifed and fltered by d5 and c5 to provide the 5.2 v output. additional fltering is provided by l2 and c6. the output voltage is determined by the sum of the optocoupler u2 led forward drop (~ 1 v) and zener diode vr1 voltage. the resistor r8, maintains a bias current through the zener to improve its voltage tolerance. a simple constant current circuit is implemented using the v be of transistor q1 to sense the voltage across the current sense resistor r4, which can be made up of one or more resistors to figure 12. 0.5 w open loop ac adapter circuit. pi-2244-082898 tinyswitch d s en bp + 5.2 v rtn d1 1n4005 c1 6.8 f 400 v fusible rf1 10 c3 0.1 f 85 - 265 vac l1 560 h d2 1n4005 d3 1n4005 d4 1n4005 r2 100 k 1 w u2 ltv817 d5 fr201 l2 3.3 h c5 220 f 25 v c2 4.7 f 400 v c6 220 f 16 v r7 100 r3 22 r4 1 1 w r9 47 q1 2n3904 r8 820 vr1 1n5230b 4.7 v c8 2.2 nf y1 safety u1 tny254p c4 2200 pf d6 1n4937 r6 0.82 1/2 w t1 r1 1.2 k 1 2 5 10 r5 18 1/8 w pi-2190-031501 tinyswitch d s en bp + 9 v rtn d1 1n4004 c1 2.2 f 200 v fusible rf1 1.8 c4 68 pf 1 kv 115 vac 15% r2 100 d2 1n4004 c3 0.1 f d3 1n3934 c6 100 f 16v c2 2.2 f 200 v vr1 1n5239b c5 2.2 nf y1 safety u1 tny253p t1 1 5 6 10
rev e 02/12 tny253/254/255 8 achieve the appropriate value. r3 is a base current limiting resistor. when the drop across r4 exceeds the v be of transistor q1, it turns on and takes over the control of the loop by driving the optocoupler led. r6 drops an additional voltage to keep the control loop in operation down to zero volts on the output. with the output shorted, the drop across r4 and r6 (~ 1.5 v) is suffcient to keep the q1 and led circuit active. resistors r7 and r9 limit the forward current that could be drawn through vr1 by q1 under output short-circuit conditions, due to the voltage drop across r6 and r4. ac adapter many consumer electronic products utilize low power 50/60 hz transformer based ac adapters. the tinyswitch can cost ef - fectively replace these linear adapters with a solution that is lighter, smaller and more energy effcient . figure 12 shows a 9 v, 0.5 w ac adapter circuit using the tny253. this circuit operates from a 115 vac input. to save cost, this circuit runs without any feedback, in discontinuous conduction mode to deliver constant power output relatively independent of in - put voltage. the output voltage is determined by the voltage drop across zener diode vr1. the primary inductance of the transformer is chosen to deliver a power that is in excess of the required output power by at least 50% to allow for component tolerances and to maintain some current through the zener vr1 at full load. at no load, all of the power is delivered to the zener which should be rated and heat sinked accordingly. in spite of a constant power consumption from the mains input, this solu - tion is still signifcantly more effcient than linear adapters up to output power levels of approximately 1 w. the ac input is rectifed by diodes d1 and d2. d2 is used to reduce conducted emi by only allowing noise onto the neutral line during diode conduction. the rectifed ac is then fltered by capacitors c1 and c2 to generate a high-voltage dc bus, which is applied to the series combination of the primary wind - ing of t1 and the high-voltage mosfet inside the tny253. the resistor r2 along with capacitors c1 and c2 form a -flter which is suffcient for meeting emi conducted emissions at these power levels. c5 is a y capacitor which is used to reduce common mode emi. due to the 700 v rating of the tinyswitch mosfet, a simple capacitive snubber (c4) is adequate to limit the leakage inductance spike in 115 vac applications, at low power levels. the secondary winding is rectifed and fltered by d3 and c6. key application considerations for the most up to date information visit our web site at: www.powerint.com design output power range the power levels shown in the tinyswitch selection guide (table 1) are approximate, recommended output power ranges that will provide a cost optimum design and are based on following assumptions: 1. the minimum dc input voltage is 90 v or higher for 85 vac input or 240 v or higher for 230 vac input or 115 vac input with a voltage doubler. 2. the tinyswitch is not thermally limited - the source pins are soldered to suffcient copper area to keep the die temperature at or below 100 c. this limitation does not usually apply to tny253 and tny254. the maximum power capability of a tinyswitch depends on the thermal environment, transformer core size and design (continuous or discontinuous), effciency required, minimum specifed input voltage, input storage capacitance, output volt - age, output diode forward drop, etc., and can be different from the values shown in the selection guide. audible noise at loads other than maximum load, the cycle skipping mode operation used in tinyswitch can generate audio frequency components in the transformer. this can cause the transformer to produce audio noise. transformer audible noise can be reduced by utilizing appropriate transformer construction techniques and decreasing the peak fux density. for more information on audio suppression techniques, please check the application notes section on our web site at www.powerint.com . ceramic capacitors that use dielectrics such as z5u, when used in clamp and snubber circuits, can also generate audio noise due to electrostriction and piezo-electric effects. if this is the case, replacing them with a capacitor having a different type of dielectric is the simplest solution. polyester flm capacitor is a good alternative. short-circuit current the tinyswitch does not have an auto-restart feature. as a result, tinyswitch will continue to deliver power to the load during output short-circuit conditions. in the worst case, peak short-circuit current is equal to the primary current limit (i limit ) multiplied by the turns ratio of the transformer (n p /n s ). in a typical design the average current is 25 to 50% lower than this peak value. at the power levels of tinyswitch this is
tny253/254/255 9 rev e 02/12 figure 13. recommended pc layout for the tinyswitch. easily accommodated by rating the output diode to handle the short-circuit current. the short-circuit current can be minimized by choosing the smallest (lowest current limit) tinyswitch for the required power. layout single point grounding use a single point ground connection at the source pin for the bypass pin capacitor and the input filter capacitor (see figure 13). primary loop area the area of the primary loop that connects the input flter ca - pacitor, transformer primary and tinyswitch together, should be kept as small as possible. primary clamp circuit a clamp or snubber circuit is used to minimize peak voltage and ringing on the drain pin at turn-off. this can be achieved by using an rc snubber for less than 3 w or an rcd clamp as shown in figure 13 for higher power. a zener and diode clamp across the primary or a single 550 v zener clamp from drain to source can also be used. in all cases care should be taken to minimize the circuit path from the snubber/clamp components to the transformer and tinyswitch. thermal considerations copper underneath the tinyswitch acts not only as a single point ground, but also as a heatsink. the hatched area shown in figure 13 should be maximized for good heat-sinking of tinyswitch and output diode. y capacitor the placement of the y capacitor should be directly from the primary single point ground to the common/return terminal on the secondary side. such placement will maximize the emi beneft of the y capacitor. optocoupler it is important to maintain the minimum circuit path from the optocoupler transistor to the tinyswitch enable and source pins to minimize noise coupling. output diode for best performance, the area of the loop connecting the secondary winding, the output diode and the output filter capacitor, should be minimized. see figure 13 for optimized layout. in addition, suffcient copper area should be provided at the anode and cathode terminals of the diode to adequately heatsink the diode under output short-circuit conditions. input and output filter capacitors there are constrictions in the traces connected to the input and output flter capacitors. these constrictions are present for two reasons. the frst is to force all the high frequency currents to fow through the capacitor (if the trace were wide then it could fow around the capacitor). secondly, the constrictions minimize the heat transferred from the tinyswitch to the input flter capacitor and from the secondary diode to the output flter capacitor. the common/return (the negative output terminal in figure 13) terminal of the output flter capacitor should be connected with a short, low resistance path to the secondary winding. in addition, the common/return output connection should be taken directly from the secondary winding pin and not from the y capacitor connection point. top view pi-2176-071398 y1- capacitor opto- coupler c bp d en bp tinyswitc h + ? hv + ? dc out input filter capacitor output filter capacitor safety spacing transformer maximize hatched copper ar eas ( ) for optimum heat sinking s s pri sec
rev e 02/12 tny253/254/255 10 storage temperature ...................................... -65 to 150 c operating junction temperature (2) ................ -40 to 150 c lead temperature (3) ................................................. 260 c thermal impedance ( ja ) .................. 70 c/w (4) , 55 c/w (5) thermal impedance ( jc ) ....................................... 11 c/w 4. soldered to 0.36 sq. inch (232 mm 2 ), 2 oz. (610 gm/m 2 ) copper clad. 5. soldered to 1 sq. inch (645 mm 2 ), 2 oz. (610 gm/m 2 ) copper clad. 6. the higher peak drain current is allowed while the drain voltage is simultaneously less than 400 v. absolute maximum ratings (1) drain voltage .......................................... -0.3 v to 700 v peak drain current (tny253/4) ............ 400 (500) ma (6) peak drain current (tny255) ............... 530 (660) ma (6) enable voltage ........................................... -0.3 v to 9 v enable current ................................................... 100 ma bypass voltage ............................................ -0.3 v to 9 v 1. all voltages referenced to source, t a = 25 c. 2. normally limited by internal circuitry. 3. 1/16" from case for 5 seconds. 40 44 48 66 68 71 -68 -50 -30 -15 -10 -5 1.10 1.45 1.80 -58 -42 -25 160 200 140 180 -2.5 5.8 0.72 control functions output frequency maximum duty cycle enable pin turnoff threshold current enable pin hysteresis current enable pin voltage enable short- circuit current drain supply current bypass pin charge current bypass pin voltage bypass hysteresis khz % a a v a a a ma ma v v min typ max f osc dc max i dis i hys v en i ensc i s1 i s2 i ch1 i ch2 v bp v bph parameter symbol (unless otherwise specifed) see figure 14 conditions tny253 tny255 tny253 tny254 tny255 tny253 tny254 tny255 tny253 tny254 tny255 130 215 -4.5 -3.3 tny254 enable open (mosfet switching) see note b, c t j = 25 c 115 140 265 -2.0 -5.0 -3.5 -4.0 -1.0 5.6 6.1 0.60 0.85 units source = 0 v ; t j = -40 to 125 c tny253 tny255 67 tny254 t j = -40 c to 125 c t j = 125 c -68 -52 -45 v en = 0 v, t j = -40 c to 125 c v en = 0 v, t j = 125 c -58 -45 -38 v bp = 0 v, t j = 25 c see note d, e v bp = 4 v, t j = 25 c see note d, e 64 69 -4.8 -1.8 -6.0 -3.0 170 215 tny253 tny254 tny255 s1 open see note a i en = -25 a v en = 0 v (mosfet not switching) see note b see note d
tny253/254/255 11 rev e 02/12 conditions parameter symbol source = 0 v; t j = -40 to 125 c see figure 14 (unless otherwise specifed) di/dt = 12.5 ma/ s t j = 25 c di/dt = 25 ma/ s t j = 25 c di/dt = 80 ma/ s t j = 25 c 135 150 165 230 255 280 255 280 310 170 240 170 215 200 250 100 150 125 135 145 70 31 36 50 60 23 27 37 45 50 700 50 50 i limit note f i init t leb t ild r ds(on) i dss bv dss t r t f ma ma ns ns c c ? a v ns ns current limit initial current limit leading edge blanking time current limit delay thermal shutdown temperature thermal shutdown hysteresis on-state resistance off-state drain leakage current breakdown voltage rise time fall time min typ max units circuit protection output v bp = 6.2 v, v en = 0 v, v ds = 560 v, t j = 125 c t j = 25 c t j = 100 c t j = 25 c t j = 100 c tny253/tny254 i d = 25 ma measured with figure 10 schematic. tny253 tny254 tny255 v bp = 6.2 v, v en = 0 v, i ds = 100 a, t j = 25 c tny253 tny254 tny255 tny253 tny254 tny255 t j = 25 c see note g tny255 i d = 33 ma see figure 17 t j = 25 c t j = 25 c 0.65 x i limit(min)
rev e 02/12 tny253/254/255 12 notes: a. for a threshold with a negative value, negative hysteresis is a decrease in magnitude of the corresponding threshold. b. total current consumption is the sum of i s1 and i dss when enable pin is shorted to ground (mosfet not switching) and the sum of i s2 and i dss when enable pin is open (mosfet switching). c. since the output mosfet is switching, it is diffcult to isolate the switching current from the supply current at the drain. an alternative is to measure the bypass pin current at 6.2 v. d. bypass pin is not intended for sourcing supply current to external circuitry. e. see typical performance characteristics section for bypass pin start-up charging waveform. f. for current limit at other di/dt values, refer to current limit vs. di/dt curve under typical performance characteristics. g. this parameter is derived from the change in current limit measured at 5x and 10x of the di/dt shown in the i limit specifcation. figure 14. tinyswitch general test circuit. pi-2211-061898 0.1 f 10 v 50 v 470 5 w s2 s1 470 note: this test circuit is not applicable for current limit or output characteristic measurements. de n bp s s s s s conditions parameter symbol source = 0 v; t j = -40 to 125 c see figure 14 (unless otherwise specifed) 50 0.5 t en t dst v s s drain supply voltage output enable delay output disable setup time min typ max units output (cont.) tny253 tny254 tny255 10 14
tny253/254/255 13 rev e 02/12 1.1 1.0 0.9 -50 -25 02 55 07 5 100 125 150 breakdown vs. temperature pi-2213-040901 typical performance characteristics figure 17. current limit envelope. figure 15. tinyswitch duty cycle measurement. pi-2194-062398 enable t p t en t p = 1 2f osc for tny253/254 dc max t p = 1 f osc for tny255 figure 16. tinyswitch output enable timing. 1.2 1.0 0.8 0.6 0.4 0.2 0 -50 -25 02 55 07 5 100 125 frequency vs. temperature pi-2238-033001 0.8 1.3 1.2 1.1 0.9 0.8 1.0 0 01 26 8 3 time (s) drain current (normalized) pi-2248-090198 45 7 0.7 0.6 0.5 0.4 0.3 0.2 0.1 i limit(max) @ 25 c i limit(min) @ 25 c i init(min) t leb (blanking time) pi-2048-033001 drain voltage hv 0 v 90% 10% 90% t 2 t 1 d = t 1 t 2
rev e 02/12 tny253/254/255 14 typical performance characteristics (continued) 1.2 1.0 0.8 0.6 0.4 0.2 0.0 0 12.5 25 37.5 50 62.5 75 87.5 100 di/dt in ma/s tny253 current limit vs. di/dt pi-2230-082798 current limit (normalized to 12.5 ma/s) 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 0 50 100 150 200 250 di/dt in ma/s tny254 current limit vs. di/dt pi-2232-082798 current limit (normalized to 25 ma/s) 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 0 160 320 480 640 800 di/dt in ma/s tny255 current limit vs. di/dt pi-2234-082798 current limit (normalized to 80 ma/s) 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 -50 -250 25 50 75 100 125 current limit vs. temperature pi-2236-033001 1.4 6 5 4 3 2 1 0 0 0.2 0.4 0.6 0.8 1.0 time (ms) bypass pin start-up waveform pi-2240-082898 bypass pin voltage (v) 7 drain voltage (v) drain current (ma) output characteristic 300 250 200 100 50 150 0 02 46 81 0 pi-2221-033001 tny253 1.00 tny254 1.00 tny255 1.33 scaling factors:
tny253/254/255 15 rev e 02/12 pi-2076-040110 1 a k j1 4 l g 8 5 c n pdip-8 (p package) d s .004 (.10) j2 -e- -d- b -f- dim a b c g h j1 j2 k l m n p q inches 0.367-0.387 0.240-0.260 0.125-0.145 0.015-0.040 0.120-0.140 0.057-0.068 0.014-0.022 0.008-0.015 0.100 bsc 0.030 (min) 0.300-0.320 0.300-0.390 0.300 bsc mm 9.32-9.83 6.10-6.60 3.18-3.68 0.38-1.02 3.05-3.56 1.45-1.73 0.36-0.56 0.20-0.38 2.54 bsc 0.76 (min) 7.62-8.13 7.62-9.91 7.62 bsc notes: 1. package dimensions conform to jedec specification ms-001-ab for standard dual in-line (dip) package .300 inch row spacing (plastic) 8 leads (issue b, 7/85). 2. controlling dimensions are inches. 3. dimensions shown do not include mold flash or other protrusions. mold flash or protrusions shall not exceed .006 (.15) on any side. 4. d, e and f are reference datums on the molded body . h m p q p08a typical performance characteristics (continued) 100 1 0 600 drain voltage (v) drain capacitance (pf) c oss vs. drain voltage 10 pi-2223-033001 200 400 tny253 1.00 tny254 1.00 tny255 1.33 scaling factors: 50 30 40 10 20 0 0 200 400 600 drain voltage (v) power (mw) drain capacitance power pi-2225-033001 tny253 1.00 tny254 1.00 tny255 1.33 scaling factors:
rev e 02/12 tny253/254/255 16 pi-2077-0401 10 1 a j1 4 l 85 c g08a smd-8 (g package) d s .004 (.10) j2 e s .010 (.25) -e- -d- b -f- m j3 dim a b c g h j1 j2 j3 j4 k l m p inches 0.367-0.387 0.240-0.260 0.125-0.145 0.004-0.012 0.036-0.044 0.057-0.068 0.048-0.053 0.032-0.037 0.007-0.01 1 0.010-0.012 0.100 bsc 0.030 (min) 0.372-0.388 0-8 mm 9.32-9.83 6.10-6.60 3.18-3.68 0.10-0.30 0.91-1.12 1.45-1.73 1.22-1.35 0.81-0.94 0.18-0.28 0.25-0.30 2.54 bsc 0.76 (min) 9.45-9.86 0-8 notes: 1. package dimensions conform to jedec specification ms-001-ab (issue b, 7/85) except for lead shape and size. 2. controlling dimensions are inches. 3. dimensions shown do not include mold flash or other protrusions. mold flash or protrusions shall not exceed .006 (.15) on any side. 4. d, e and f are reference datums on the molded body . k g h .004 (.10) j4 p .010 (.25) m a s .420 .046 .060 .060 .046 .080 pin 1 .086 .186 .286 solder pad dimensions revision notes date a - 02/99 b 1. leading edge blanking time (t leb ) typical and minimum values increased to improve design fexibility. 2. minimum drain supply current (i s1 , i s2 ) eliminated as it has no design revelance. 07/01 c 1. updated package reference. 2. corrected vr1 in figure 12. 3. corrected storage temperature, ja and jc and updated nomenclature in parameter table. 4. corrected spacing and font sizes in fgures. d 1. corrected ja for p/g package. 2. updated dip-8 and smd-8 package drawings. 3. figure 10 caption and text description modifed. 04/03 e 1. changed soa limit. 02/12
tny253/254/255 17 rev e 02/12 notes
rev e 02/12 tny253/254/255 18 for the latest updates, visit our website: www.powerint.com power integrations reserves the right to make changes to its products at any time to improve reliability or manufacturability. power integrations does not assume any liability arising from the use of any device or circuit described herein. power integrations makes no warranty herein and specifically disclaims all warranties including, without limitation, the implied warranties of merchantability, fitness for a particular purpose, and non-infringement of third party rights. patent information the products and applications illustrated herein (including transformer construction and circuits external to the products) may be covered by one or more u.s. and foreign patents, or potentially by pending u.s. and foreign patent applications assigned to power integrations. a complete list of power integrations patents may be found at www.powerint.com. power integrations grants its customers a license under certain patent rights as set forth at http://www.powerint.com/ip.htm. life support policy power integrations products are not authorized for use as critical components in life support devices or systems without the express written approval of the president of power integrations. as used herein: 1. a life support device or system is one which, (i) is intended for surgical implant into the body, or (ii) supports or sustains life, and (iii) whose failure to perform, when properly used in accordance with instructions for use, can be reasonably expected to result in signifcant injury or death to the user. 2. a critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. the pi logo, topswitch, tinyswitch, linkswitch, dpa-switch, peakswitch, capzero, senzero, linkzero, hiperpfs, hipertfs, hiperlcs, qspeed, ecosmart, clampless, e-shield, filterfuse, stakfet, pi expert and pi facts are trademarks of power integrations, inc. other trademarks are property of their respective companies. ?2012, power integrations, inc. power integrations worldwide sales support locations world headquarters 5245 hellyer avenue san jose, ca 95138, usa. main: +1-408-414-9200 customer service: phone: +1-408-414-9665 fax: +1-408-414-9765 e-mail: usasales@powerint.com china (shanghai) rm 1601/1610, tower 1, kerry everbright city no. 218 tianmu road west, shanghai, p.r.c. 200070 phone: +86-21-6354-6323 fax: +86-21-6354-6325 e-mail: chinasales@powerint.com china (shenzhen) 3rd floor, block a, zhongtou international business center, no. 1061, xiang mei rd, futian district, shenzhen, china, 518040 phone: +86-755-8379-3243 fax: +86-755-8379-5828 e-mail: chinasales@powerint.com germany rueckertstrasse 3 d-80336, munich germany phone: +49-89-5527-3910 fax: +49-89-5527-3920 e-mail: eurosales@powerint.com india #1, 14th main road vasanthanagar bangalore-560052 india phone: +91-80-4113-8020 fax: +91-80-4113-8023 e-mail: indiasales@powerint.com italy via de amicis 2 20091 bresso mi italy phone: +39-028-928-6000 fax: +39-028-928-6009 e-mail: eurosales@powerint.com japan kosei dai-3 bldg. 2-12-11, shin-yokomana, kohoku-ku yokohama-shi kanagwan 222-0033 japan phone: +81-45-471-1021 fax: +81-45-471-3717 e-mail: japansales@powerint.com korea rm 602, 6fl korea city air terminal b/d, 159-6 samsung-dong, kangnam-gu, seoul, 135-728, korea phone: +82-2-2016-6610 fax: +82-2-2016-6630 e-mail: koreasales@powerint.com singapore 51 newton road #15-08/10 goldhill plaza singapore, 308900 phone: +65-6358-2160 fax: +65-6358-2015 e-mail: singaporesales@powerint.com taiwan 5f, no. 318, nei hu rd., sec. 1 nei hu dist. taipei, taiwan 114, r.o.c. phone: +886-2-2659-4570 fax: +886-2-2659-4550 e-mail: taiwansales@powerint.com europe hq 1st floor, st. jamess house east street, farnham surrey gu9 7tj united kingdom phone: +44 (0) 1252-730-141 fax: +44 (0) 1252-727-689 e-mail: eurosales@powerint.com applications hotline world wide +1-408-414-9660 applications fax world wide +1-408-414-9760
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