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innovative power tm - 1 - www.active-semi.com copyright ? 2014 active-semi, inc. active-semi proprietary D for authorized recipients and customers activeqr tm is a trademark of active-semi. rev 4, 13-feb-14 activeqr tm quasi-resonant pwm controller features ? ccm and quasi-resonant operation ? adjustable up to 75khz switching frequency ? ocp/olp protection ? integrated patented frequency foldback technique ? integrated patented line compensation ? built-in soft-start circuit ? line under-voltage, thermal, output over- voltage, output short protections ? current sense resistor short protection ? transformer winding short protection ? 100mw standby power ? complies with global energy efficiency and cec average efficiency standards ? tiny sot23-6 packages applications ? ac/dc adaptors/chargers for cell phones, cordless phone, pdas, e-books ? adaptors for portable media player, dscs, set-top boxes, dvd players, records ? linear adapter replacements general description the act512 is a high performance peak current mode pwm controller. act512 applies activeqr tm and frequency foldback technique to reduce emi and improve efficiency. act512?s maximum design switching frequency is set at 75khz. very low standby power, good dynamic response and accurate voltage regulation is achieved with an opto-coupler and the secondary side control circuit. the idle mode operation enables low standby power of 100mw with small output voltage ripple. by applying frequency foldback and activeqr tm technology, act512 increases the average system efficiency compared to conventional solutions and exceeds the latest es2.0 efficiency standard with good margin. act512 integrates comprehensive protection. in case of over temperatur e, over voltage, winding short, current sense resistor short, open loop and overload conditions, it would enter into auto restart mode including cycle-by-cycle current limiting. act512 is to achieve no overshoot and very short rise time even with a big capacitive load with the built-in fast and soft start process. in full load condition, act512 is able to be designed to work in both ccm mode and dcm mode to meet different types of applications. quasi- resonant (qr) operation mode can improve efficiency during dcm operation, and reduce emi and further reduce the components in input filter. act512 is ideal for applications up to 60 watts. figure 1: simplified application circuit act512
act512 rev 4, 13-feb-14 innovative power tm - 2 - www.active-semi.com copyright ? 2014 active-semi, inc. active-semi proprietary D for authorized recipients and customers activeqr tm is a trademark of active-semi. pin configuration pin descriptions part number temperature range package pins packing method top mark act512us-t -40c to 85c sot23-6 6 tube & reel fsht sot23-6 act512us ordering information pin name description 1 cs current sense pin. connect an external resistor (r cs ) between this pin and ground to set peak current limit for the primary switch. 2 gnd ground. 3 gate gate drive. gate driver fo r the external mosfet transistor. 4 vdd power supply. this pin provides bias power fo r the ic during startup an d steady state operation. 5 vdet valley detector pin. connect this pin to a resist or divider network from the auxiliary winding to detect zero-crossing points for valley turn on operation. 6 fb feedback pin. connect this pin to opt ocouplers?s collector for output regulation.
act512 rev 4, 13-feb-14 innovative power tm - 3 - www.active-semi.com copyright ? 2014 active-semi, inc. active-semi proprietary D for authorized recipients and customers activeqr tm is a trademark of active-semi. absolute maximum ratings c electrical characteristics (v dd = 14v, l m = 0.8mh, r cs = 0.87 ? , v out = 12v, n p = 56, n s =9, n a =10, t a = 25c, unless otherwise specified.) c : do not exceed these limits to prevent damage to the device. exposure to absolute maximum ra ting conditions fo r long periods. parameter value unit fb, cs, vdet to gnd -0.3 to + 6 v vdd, gate to gnd -0.3 to + 28 v maximum power dissipation (sot23-6) 0.45 w operating junction temperature -40 to 150 ? c junction to ambient thermal resistance ( ja ) 220 ? c/w storage temperature -55 to 150 ? c lead temperature (soldering, 10 sec) 300 ? c parameter symbol test conditions min typ max unit supply vdd turn-on voltage v ddon v dd rising from 0v 11.3 12.3 13.3 v vdd turn-off voltage v ddoff v dd falling after turn-on 6.7 7.4 8.1 v vdd over voltage protection v ddovp v dd rising from 0v 25 v start up supply current i ddst v dd = 10v, before vdd turn-on 8 15 a idd supply current i dd v dd = 15v, after vdd turn-on ,fb floating 0.6 ma idd supply current at standby i ddstby fb = 1.3v 0.4 ma idd supply current at fault i ddfault fault mode, fb floating 250 a feedback fb pull up resistor r fb 15 k ? cs to fb gain a cs 3 v/v vfb at max peak current 3 + v be v fb threshold to stop switching v fbbm1 1.32 v fb threshold to start switching v fbbm2 1.41 v output overload threshold 4.2 v overload/over voltage blanking time t ovblank 320 ms
act512 rev 4, 13-feb-14 innovative power tm - 4 - www.active-semi.com copyright ? 2014 active-semi, inc. active-semi proprietary D for authorized recipients and customers activeqr tm is a trademark of active-semi. parameter symbol test conditions min typ max unit current limit cs current limit threshold v cslim 0.91 0.96 1.01 v leading edge blanking time t csblank 240 300 360 ns gate drive gate rise time t rise vdd = 10v, cl = 1nf 150 250 ns gate falling time t fall vdd = 10v, cl = 1nf 115 200 ns gate low level on-resistance r onlo i sink = 30ma 7 ? gate high level on-resistance r onhi i source = 30ma 40 ? gate leakage current gate = 25v, before vdd turn-on 1 a oscillator maximum switching frequency f max 75 khz switching frequency foldback f min fb = 2.3v+v be f max /3 khz maximum duty cycle d max 65 75 % valley detection zcd threshold voltage vdet th 100 mv valley detection time window after valley detection time window, if no valley de- tected, forcedly turn-on main switch 3.5 s vdet leakage current 1 a protection cs short waiting time 2 s cs short detection threshold 0.115 v cs open threshold voltage 1.73 v abnormal ocp blanking time 150 ns thermal shutdown temperature 135 ? c line uvlo i vdetuvlo 0.1 ma line ovp i vdetovp 2 ma vdet over voltage protection v detvoovp 2.448 2.72 2.992 v vdet vo short threshold v detvoshort 0.406 0.58 0.754 v electrical characteristics cont?d (v dd = 14v, l m = 0.8mh, r cs = 0.87 ? , v out = 12v, n p = 54, n s = 9, n a = 10, t a = 25c, unless otherwise specified.)
act512 rev 4, 13-feb-14 innovative power tm - 5 - www.active-semi.com copyright ? 2014 active-semi, inc. active-semi proprietary D for authorized recipients and customers activeqr tm is a trademark of active-semi. functional block diagram
act512 rev 4, 13-feb-14 innovative power tm - 6 - www.active-semi.com copyright ? 2014 active-semi, inc. active-semi proprietary D for authorized recipients and customers activeqr tm is a trademark of active-semi. act512 is a high performance peak current mode low-voltage pwm controller ic. the controller includes the most advance features that are required in the adaptor applications up to 60 watt. unique fast startup, frequency foldback, qr switching technique, accurate peak current line compensation, idle mode, short winding protection, ocp, otp, ovp and uvlo are included in the controller. startup startup current of act512 is designed to be very low so that vdd could be charged to v ddon threshold level and device starts up quickly. a large value startup resistor can therefore be used to minimize the power loss yet reliable startup in application. for a typical ac/dc adaptor with universal input range design, two 1m ? , 1/8 w startup resistors could be used together with a vdd capacitor(4.7uf) to provide a fast startup and yet low power dissipation design solution. during startup period, the ic begins to operate with minimum ippk to minimize the switching stresses for the main switch, output diode and transformers. and then, the ic operates at maximum power output to achieve fast rise time. after this, v out reaches about 90% v out , the ic operates with a ?soft-landing? mode(decrease ippk) to avoid output overshoot. constant voltage (cv) mode operation in constant voltage operation, the act512 regulates its output voltage through secondary side control circuit . the output voltage information is sensed at fb pin through opto coupling. the error signal at fb pin is amplified through tl431 and opto circuit. when the secondary output voltage is above regulation, the error amplifier output voltage decreases to reduce the switch current. when the secondary output voltage is below regulation, the error amplifier output voltage increases to ramp up the switch current to bring the secondary output back to regulation. the ou tput regulation voltage is determined by the following relationship: where r f1 (r15) and r f2 (r16) are top and bottom feedback resistor of the tl431. no load idle mode in no load standby mode, the feedback voltage falls below v fbbm2 and reaches v fbbm1 , act512 stop switching. after it stops, as a result of a feedback reaction, the feedback voltage increases. when the feedback voltage reaches v fbbm2 , act512 start switching again. feedback voltage drops again and output voltage starts to bounds back and forward with very small output ripple. act512 leaves idle mode when load is added strong enough to pull feedback voltage exceed v fbbm2. figure 2: idle mode primary inductor current limit compensation the act512 integrates a primary inductor peak current limit compensation circuit to achieve constant olp over wide line and wide inductance. frequency foldback when the load drops to 75% of full load level, act512 starts to reduce the switching frequency, which is proportional to the load current ,to improve the efficiency of the converter. act512?s load adaptive switching frequency enables applications to meet all latest green energy standards. the actual minimum average switching frequency is programmable with output capacitance, feedback circuit and dummy load (while still meeti ng standby power). valley switching act512 employed valley switching from no load to heavy load to reduce switching loss and emi. in discontinuous mode operation, the resonant voltage between inductance and parasitic capacitance on mosfet source pin is coupled by auxiliary winding and reflected on vdet pin through feedback network r5, r6. internally, the vdet pin is connected to an zero-crossing detector to generate the switch turn on signal when the conditions are met. functional description (1) ) r r 1 ( v v 2 f 1 f 431 tl _ ref outcv + = ip vo vfb t ip_fl ilim vfb_fl vfb_olp 2a vfbbm1 io 12v vfbbm2 0a
act512 rev 4, 13-feb-14 innovative power tm - 7 - www.active-semi.com copyright ? 2014 active-semi, inc. active-semi proprietary D for authorized recipients and customers activeqr tm is a trademark of active-semi. figure 3: valley switching protection features the act512 provides full protection functions. the following table summarizes all protection functions. auto-restart operation act512 will enter into auto-restart mode when a fault is identified. there is a startup phase in the auto-restart mode. after this startup phase the conditions are checked whet her the failure is still present. normal operation proceeds once the failure mode is removed. otherwise, new startup phase will be initiated again. to reduce the power loss during fault mode, the startup delay control is implemented. the startup delay time increases over lines. functional description cont?d protection functions failure condition protection mode v dd over voltage v dd > 25v (4 duty cycle) auto restart v vdet over volt- age/no voltage v vd > 2.72v or no switching for 4 cycles auto restart over temperature t > 135 ? c auto restart short winding/ short diode v cs > 1.72v auto restart over load/open loop ipk = i limit or v fb = 3.5v + v be for 320ms auto restart output short circuit v det < 0.58v auto restart v dd under volt- age v dd < 7.4v auto restart vdrain_gnd t dc voltage t ton possible valley turn on v
act512 rev 4, 13-feb-14 innovative power tm - 8 - www.active-semi.com copyright ? 2014 active-semi, inc. active-semi proprietary D for authorized recipients and customers activeqr tm is a trademark of active-semi. typical application design example the design example below gives the procedure for 12v/2a flyback converter using act512. refer to application circuit figure 4, the design for an adapter application starts with the following specification: the operation for the circuit shown in figure 4 is as follows: the rectifier bridge d1 ? d4 and the capacitor c1/c2 convert the ac line voltage to dc bus voltage. this voltage supplies the primary winding of the transformer t1 and the startup circuit of r7/ r8 and c4 to vdd pin of act512. the primary power current path is formed by the transformer?s primary winding, q1, and the current sense resistor r9. the resistors r3, r2, diode d5 and capacitor c3 create a snubber clamping network that protects q1 from damage due to high voltage spike during q1?s turn off. the network consisting of capacitor c4, diode d6 and resistor r4 provides a vdd supply voltage for act512 from the auxiliary winding of the transformer. the resistor r4 is optional, which filters out spikes and noise to makes vdd more stable. c4 is the decoupling capacitor of the supply voltage and energy storage component for startup. during power startup, the current charges c4 through startup resistor r7/r8 from the rectified bus voltage. the diode d8 and the capacitor c5/l2/c6 rectify filter the output voltage. the resistor divider consists of r15 and r16 programs the output voltage. since a bridge rectifier and bulk input capacitors are used, the resulting minimum and maximum dc input voltages can be calculated: where ? is the estimated circuit efficiency, f l is the line frequency, t c is the estimated rectifier conduction time, c in is empirically selected to be 47f electrolytic capacitors. the maximum duty cycle is set to be 45% at low line voltage 90vac and the circuit efficiency is estimated to be 86%. then in ccm the primary to secondary turn ratio n p /n s: ef25 core is selected for the transformer. the core minimum ae is 0.51cm^2. the minimum turn of the primary winding is: vdd voltage is set to 13v, base on the data we can get primary, secondly and auxiliary turns: we set dcm/ccm boundary is 185vac,then the duty at full load is: the peak current of primary is: the primary inductance is: v 90 f 47 86 . 0 ) ms 5 . 3 47 2 1 ( 24 2 90 2 c ) t f 2 1 ( p 2 v 2 v 2 in c l out 2 min _ inac min _ indc - - - = = (2) v 375 ) v 265 ( 2 v 2 v ac ac ) max ( in dc ) max ( in = = = (3) 136 . 6 12 ) 45 . 0 1 ( 90 45 . 0 v ) d 1 ( v d n n o max _ ccm min _ in max _ ccm s p = ? = ? = (4) t 42 51 . 0 2500 75000 10 45 . 0 90 ) cm gaus ( ae b f 10 d v n 8 2 min max max 8 max _ ccm min _ in p = = (5) 22 . 0 5 6 1 2 9 414 . 1 18 5 56 12 n v n v n v d p o s indc p o ccm = + = + = (8) (9) a 97 . 0 86 . 0 22 . 0 414 . 1 185 2 12 2 d v i v 2 i dcm in o o ppk = = = (10) input voltage range 90vac - 265vac, 50/60hz output power, p o 24w output voltage, v outcv 12v full load current, i outfl 2a ocp current, i outmax 2.3-2.6a system efficiency cv, 0.86 (7) t 10 n , t 9 n , t 56 n a s p = = = = = = 1 . 1 45 . 0 12 7 . 0 13 v v v v n n sec _ d o aux _ d dd s a = + + = + + =
act512 rev 4, 13-feb-14 innovative power tm - 9 - www.active-semi.com copyright ? 2014 active-semi, inc. active-semi proprietary D for authorized recipients and customers activeqr tm is a trademark of active-semi. typical application cont?d determining the value of t he current sense resistor (r7) uses the maximum current in the design. so the input primary maximum current at maximum load: since the act512 internal current limit is set to 0.96v, the design of the current sense resistor is given by: the voltage feedback resistors are selected according to the design. because the line uvlo is 75vdc, the upper feedback resistor is given by: the lower feedback resistor is selected as: when selecting the output capacitor, a low esr electrolytic capacitor is recommended to minimize ripple from the current ripple. the approximate equation for the output capacitance value is given by: two 680f electrolytic capacitors are used to further reduce the output ripple. pcb layout guideline good pcb layout is critical to have optimal performance. decoupling capacitor (c4) and feedback resistor (r5/r6) should be placed close to vdd and fb pin respectively. there are two main power path loops. one is formed by c1/c2, primary winding, mosfet transistor and current sense resistor (r9). the other is secondary winding, rectifier d8 and output capacitors (c5/c6). keep these loop areas as small as possible. connecting high current ground returns, the input capacitor ground lead, and the act512 gnd pin to a single point (star ground configuration). (11) (12) 87 . 0 1 . 1 96 . 0 i v r ocp _ p cs cs = = (13) k 9 . 54 ma 2 . 0 56 10 60 i n n v r uvlo _ fb p a uvlo _ indc up _ fb = = (14) k 7 . 11 k 9 . 54 2 . 2 1 . 1 ) 45 . 0 12 ( 2 . 2 r v n n ) v v ( v r up _ fb fb s a d out low _ fb fb + = + = - - f 533 mv 50 k 75 2 v f i c ripple sw out out = = = (15) a 1 . 1 86 . 0 75 8 . 0 12 6 . 2 2 f l v i 2 i sw p out ocp _ out ocp _ p = = =
act512 rev 4, 13-feb-14 innovative power tm - 10 - www.active-semi.com copyright ? 2014 active-semi, inc. active-semi proprietary D for authorized recipients and customers activeqr tm is a trademark of active-semi. figure 4: universal vac input, 12v/2a output adaptor
act512 rev 4, 13-feb-14 innovative power tm - 11 - www.active-semi.com copyright ? 2014 active-semi, inc. active-semi proprietary D for authorized recipients and customers activeqr tm is a trademark of active-semi. item reference description qty manufacturer 1 u1 ic, act512, sot23-6 1 active-semi 2 c1 capacitor, electrolytic, 47f/400v, 16 14mm 1 ksc 3 c3 capacitor, ceramic,1000pf/500v,0805,smd 1 poe 4 c4 capacitor, electrolytic, 4.7f/35v, 5 11mm 1 ksc 5 c5,c6 capacitor, electrolytic, 680f/25v, 10 11.5mm 2 ksc 6 c8 capacitor, ceramic, 0.1f/50v,0805,smd 1 poe 7 c9 capacitor, ceramic,1000pf/100v,0805,smd 1 poe 8 cfb capacitor, ceramic, 1000pf/50v,0805,smd 1 poe 9 d1-d4 diode, rectifier ,1000v2a, rl207, do-41 4 good-ark 10 d5,d6 diode, ultra fast, fr107,1000v/1.0a, do-41 2 good-ark 11 d8 diode, schottky, 100v/20a , sbl20100, do-220 1 good-ark 12 l1 cm inductor, 30mh, uu10.5 1 soka 13 bead1,2 t6*2*3, r5 2 soka 14 l3 dm inductor, 3h, r5 1 soka 15 q1 mosfet transisor, 4n65, to-220f 1 st 16 pcb1 pcb, l*w*t = 48.5 29 1.6mm, cem-1, rev:a 1 jintong 17 f1 fusible, 2a/250v 1 ty-ohm 18 r12 chip resistor, 3.3k ? , 0805, 5% 1 ty-ohm 19 r2 carbon resistor, 100k ? , 2w, 5% 1 ty-ohm 20 r3 chip resistor, 100 ? , 0805, 5% 1 ty-ohm 21 r4 chip resistor, 4.7 ? , 0805, 5% 1 ty-ohm 22 r5 chip resistor, 54.9k ? , 0805, 1% 1 ty-ohm 23 r6 chip resistor, 11.7k ? , 0805, 1% 1 ty-ohm 24 r7,r8 chip resistor, 1m ? , 0805, 5% 2 ty-ohm 25 r9 chip resistor, 0.87 ? ,1w, 1% 1 ty-ohm 26 r10 chip resistor, 510 ? , 0805, 5% 1 ty-ohm 27 r14 chip resistor, 300k ? , 0805, 5% 1 ty-ohm 28 r15 chip resistor, 23.7k ? , 0805, 1% 1 ty-ohm 29 r16 chip resistor, 6.19k ? , 0805, 1% 1 ty-ohm 30 rgate chip resistor, 47 ? , 0805, 5% 1 ty-ohm 31 t1 transformer, l p = 0.8mh, rm8 1 32 ntc thermistor, sc053 1 ty-ohm 33 tvs varistor, 10471 1 ty-ohm 34 cx1 x capacitance, 0.22f/400v,x1 2 35 cy1 y capacitance, 2200pf/400v,y1 1 sec 36 u2 opto-coupler, pc817c ctr = 200% 1 sharp 37 u3 voltage regulator, tl431a, v ref = 2.5v 1 st table 1: act512 12v24w bill of materials
act512 rev 4, 13-feb-14 innovative power tm - 12 - www.active-semi.com copyright ? 2014 active-semi, inc. active-semi proprietary D for authorized recipients and customers activeqr tm is a trademark of active-semi. typical performanc e characteristics act512-001 vdd on/off voltage vs. temperature 13.5 12.5 11.5 10.5 9.5 8.5 7.5 6.5 v ddon and v ddoff (v) temperature (c) 0 40 120 80 v ddoff act512-002 startup supply current vs. temperature 8 7 6 9 startup supply current (a) act512-003 supply current at idle/fault mode vs. temperature supply current (ma) 0.4 0.3 0.2 act512-004 maximum switching frequency vs. temperature 90 70 60 80 maximum switching frequency (khz) act512-005 v cs voltage vs. temperature v cs voltage (v) 1.0 0.9 0.8 0.7 0.6 act512-006 v fb threshold voltage vs. temperature v fb threshold voltage (v) 4 3 2 1 0 5 v ddon temperature (c) 0 20 60 40 80 100 120 stop switching start switching idle mode fault mode temperature (c) 0 20 60 40 80 100 120 temperature (c) 0 20 60 40 80 100 120 temperature (c) 0 20 60 40 80 100 120 temperature (c) 0 20 60 40 80 100 120 olp
act512 rev 4, 13-feb-14 innovative power tm - 13 - www.active-semi.com copyright ? 2014 active-semi, inc. active-semi proprietary D for authorized recipients and customers activeqr tm is a trademark of active-semi. package outline sot23-6 package outline and dimensions active-semi, inc. reserves the right to modify the circuitry or specifications without notice. user s should evaluate each product to make sure that it is suitable for their applicat ions. active-semi products are not intended or authorized for use as critical components in life-support dev ices or systems. active-semi, inc. does not assume any liability arising out of the use of any product or circuit described in this datasheet, nor does it convey any patent license. active-semi and its logo are trademarks of active-semi, inc. for more information on this and other products, contact sales@active-semi.com or visit http://www.active-semi.com . is a registered trademark of active-semi.
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