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innovative power tm - 1 - www.active-semi.com copyright ? 2012 active-semi, inc. features ? up to 40v input voltage ? up to 2a output current ? output voltage up to 12v ? patent pending active cc sensorless constant current control ? integrated current control improves efficiency, lowers cost, and reduces component count ? resistor programmable ? current limit from 750ma to 2a ? patented cable compensation from 0 ? to 0.5 ? ? 7.5% cc accuracy ? compensation of input /output voltage change ? temperature compensation ? independent of inductance and inductor dcr ? 2% feedback voltage accuracy ? up to 93% efficiency ? 210khz switching frequency eases emi design ? advanced feature set ? integrated soft start ? thermal shutdown ? secondary cycle-by-cycle current limit ? protection against shorted iset pin ? sop-8ep package applications ? car charger/ adaptor ? rechargeable portable devices ? general-purpose cc/cv supply general description act4513 is a wide input voltage, high efficiency active cc step-down dc/dc converter that operates in either cv (c onstant output voltage) mode or cc (constant output current) mode. act4513 provides up to 2a output current at 210khz switching frequency. active cc is a patent-pending control scheme to achieve highest accuracy sensorless constant current control. active cc eliminates the expensive, high accuracy current sense resistor, making it ideal for battery charging applications and adaptors with accurate current limit. the act4513 achieves higher efficiency than traditional constant current switching regulators by eliminating its associated power loss. protection features include cycle-by-cycle current limit, thermal shutdown, and frequency foldback at short circuit. the devices are available in a sop- 8ep package and require very few external devices for operation. act4513 wide-input sensorless cc/cv step-down dc/dc converter rev 7, 14-nov-12 output voltage (v) output current (a) 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 act4513-001 6.0 5.0 4.0 3.0 2.0 1.0 0.0 cc/cv curve v in = 24v v in = 12v
act4513 rev 7, 14-nov-12 innovative power tm - 2 - www.active-semi.com copyright ? 2012 active-semi, inc. ordering information part number operation temperature range package pins packing act4513yh-t -40c to 85c sop-8ep 8 tape & reel pin configuration pin descriptions pin name description 1 hsb high side bias pin. this provides power to the internal high-side mosfet gate driver. connect a 10nf capacitor from hsb pin to sw pin. 2 in power supply input. bypass this pin with a 10f ceramic capacitor to gnd, placed as close to the ic as possible. 3 sw power switching output to external inductor. 4 gnd ground. connect this pin to a large pcb copper area for best heat dissipation. return fb, comp, and iset to this gnd, and con nect this gnd to power gnd at a single point for best noise immunity. 5 fb feedback input. the voltage at this pin is re gulated to 0.808v. connect to the resistor divider between output and gnd to set the output voltage. 6 comp error amplifier output. this pi n is used to compensate the converter. 7 en enable input. en is pulled up to 5v with a 4 a current, and contains a precise 0.8v logic threshold. drive this pin to a logic-high or leave unconnected to enable the ic. drive to a logic-low to disable the ic and enter shutdown mode. 8 iset output current setting pin. connect a resi stor from iset to gnd to program the output current. exposed pad heat dissipation pad. connect this exposed pad to large ground copper area with copper and vias.
act4513 rev 7, 14-nov-12 innovative power tm - 3 - www.active-semi.com copyright ? 2012 active-semi, inc. absolute maximum ratings c parameter value unit in to gnd -0.3 to 40 v sw to gnd -1 to v in + 1 v hsb to gnd v sw - 0.3 to v sw + 7 v fb, en, iset, comp to gnd -0.3 to + 6 v junction to ambient the rmal resistance 50 c/w operating junction temperature -40 to 135 c storage junction temperature -55 to 150 c lead temperature (soldering 10 sec.) 300 c c : do not exceed these limits to prevent damage to the device. exposure to absolute maximum rati ng conditions for long periods m ay affect device reliability.
act4513 rev 7, 14-nov-12 innovative power tm - 4 - www.active-semi.com copyright ? 2012 active-semi, inc. parameter test conditions min typ max unit input voltage 10 40 v v in uvlo turn-on voltage input vo ltage rising 9.05 9.35 9.65 v v in uvlo hysteresis input voltage falling 1.1 v v en = 3v, v fb = 1v 1.0 ma v en = 3v, v out = 5v, no load 2.5 ma shutdown supply current v en = 0v 75 100 a feedback voltage 792 808 824 mv internal soft-start time 400 s error amplifier transconductance v fb = v comp = 0.8v, ? i comp = 10a 650 a/v error amplifier dc gain 4000 v/v switching frequency v fb = 0.808v 190 210 240 khz foldback switching frequency v fb = 0v 30 khz maximum duty cycle 88 % minimum on-time 200 ns comp to current limit transconductance v comp = 1.2v 3.4 a/v secondary cycle-by-cycle current limit duty = 50% 3.2 a slope compensation duty = d max 0.75 a iset voltage 1 v iset to iout dc room temp current gain iout / iset 25000 a/a cc controller dc accuracy r iset = 19.6k ? , v in = 10v - 30v 1274 1300 1326 ma en threshold voltage en pin rising 0.75 0.8 0.85 v en hysteresis en pin falling 80 mv en internal pull-up current 4 a high-side switch on-resistance 0.22 ? sw off leakage current v en = v sw = 0v 1 10 a thermal shutdown temperature temperature rising 155 c standby supply current electrical characteristics (v in = 14v, t a = 25c, unless otherwise specified.)
act4513 rev 7, 14-nov-12 innovative power tm - 5 - www.active-semi.com copyright ? 2012 active-semi, inc. functional block diagram functional description cv/cc loop regulation as seen in functional block diagram , the act4513 is a peak current mode pulse width modulation (pwm) converter with cc and cv control. the converter operates as follows: a switching cycle starts when the rising edge of the oscillator clock output ca uses the high-side power switch to turn on and the low-side power switch to turn off. with the sw side of the inductor now connected to in, the inductor current ramps up to store energy in the magnetic field. the inductor current level is measured by the current sense amplifier and added to the oscillator ramp signal. if the resulting summation is higher than the comp voltage, the output of the pwm comparator goes high. when this happens or when oscillator clock output goes low, the high-side power switch turns off. at this point, the sw side of the inductor swings to a diode voltage below ground, causing the inductor current to decrease and magnetic energy to be transferred to output. this state continues until the cycle starts again. the high-side power switch is driven by logic using hsb as the positive rail. this pin is charged to v sw + 5v when the low-side power switch turns on. the comp voltage is the integration of the error between fb input and the internal 0.808v reference. if fb is lower than the reference voltage, comp tends to go higher to increase current to the ou tput. output current will increase until it reaches the cc limit set by the iset resistor. at this point, t he device will transition from regulating output voltage to regulating output current, and the output voltage will drop with increasing load. the oscillator normally switches at 210khz. however, if fb voltage is less than 0.6v, then the switching frequency decreases until it reaches a typical value of 30khz at v fb = 0.15v. enable pin the act4513 has an enable input en for turning the ic on or off. the en pin contains a precision 0.8v comparator with 75mv hysteresis and a 4a pull-up current source. the comparator can be used with a resistor divider from v in to program a startup voltage higher than the normal uvlo value. it can be used with a resistor divider from v out to disable charging of a deeply discharged battery, or it can be used with a resistor divider containing a thermistor to provide a temperature-dependent shutoff protection for over temperature battery. the thermistor should be thermally coupled to the battery pack for this usage. if left floating, the en pin will be pulled up to roughly 5v by the internal 4a current source. it can be driven from standard logic signals greater than 0.8v, or driven with open-drain logic to provide digital on/off control. thermal shutdown the act4513 disables switching when its junction temperature exceeds 155c and resumes when the temperature has dropped by 20c. en fb bandgap, regulator, & shutdown control + - oscillator v ref = 0.808v emi control pwm controller cc control sw hsb in avin pvin comp iset v ref = 0.808v
act4513 rev 7, 14-nov-12 innovative power tm - 6 - www.active-semi.com copyright ? 2012 active-semi, inc. (1) applications information output voltage setting figure 1: output voltage setting figure 1 shows the connections for setting the output voltage. select the proper ratio of the two feedback resistors r fb1 and r fb2 based on the output voltage. typically, use r fb2 10k ? and determine r fb1 from the following equation: cc current setting act4513 constant current value is set by a resistor connected between the iset pin and gnd. the cc output current is linearly proportional to the current flowing out of the iset pin. the voltage at iset is roughly 1v and the current gain from iset to output is roughly 25000 (25ma/1a). to determine the proper resistor for a desired current, please refer to figure 2 below. figure 2: curve for programming output cc current cc current line compensation when operating at cons tant current mode, the current limit increase slightly with input voltage. for wide input voltage applications, a resistor r c is added to compensate line change and keep output high cc accuracy, as shown in figure 3. figure 3: iutput line compensation inductor selection the inductor maintains a continuous current to the output load. this inductor cu rrent has a ripple that is dependent on the inductance value: higher inductance reduces the peak-to-peak ripple current. the trade off for high inductance value is the increase in inductor core size and series resistance, and the reduction in current handling capability. in general, select an inductance value l based on ripple current requirement: where v in is the input voltage, v out is the output voltage, f sw is the switching frequency, i loadmax is the maximum load current, and k ripple is the ripple factor. typically, choose k ripple = 30% to correspond to the peak-to-peak ripple current being 30% of the maximum load current. with a selected inductor value the peak-to-peak inductor current is estimated as: the peak inductor current is estimated as: output current vs. r iset act4513-002 output current (ma) r iset (k ? ) 0 10 20 30 40 50 60 70 90 80 2400 2000 1600 1200 800 400 0 ? ? ? ? ? ? ? = 1 v 808 . 0 v r r out 2 fb 1 fb (2) ( ) ripple loadmax sw in out in out k i f v v v v l _ = (3) ( ) sw in out in out pk lpk f v l v v v i = _ _ pk lpk loadmax lpk _ i 2 1 i i + = (4) r c r iset in v in iset act4513
act4513 rev 7, 14-nov-12 innovative power tm - 7 - www.active-semi.com copyright ? 2012 active-semi, inc. (6) esr ripple outmax ripple r k i v = out 2 sw in lc f 28 v + applications information cont?d the selected inductor should not saturate at i lpk. the maximum output current is calculated as: l lim is the internal current limit, which is typically 3.2a, as shown in electrical characteristics table. external high voltage bias diode it is recommended that an external high voltage bias diode be added when the system has a 5v fixed input or the power supply generates a 5v output. this helps improve the efficiency of the regulator. the high voltage bias diode can be a low cost one such as in4148 or bat54. figure 4: external high voltage bias diode this diode is also recommended for high duty cycle operation and high output voltage applications. input capacitor the input capacitor needs to be carefully selected to maintain sufficiently low ripple at the supply input of the converter. a low esr capacitor is highly recommended. since large current flows in and out of this capacitor during switching, its esr also affects efficiency. the input capacitance needs to be higher than 10f. the best choice is the ceramic type, however, low esr tantalum or electrolytic types may also be used provided that the rms ripple current rating is higher than 50% of the output current. the input capacitor should be placed close to the in and gnd pins of the ic, with the shortest traces possible. in the case of tantalum or electrolytic types, they ca n be further away if a small parallel 0.1f ceramic capacitor is placed right next to the ic. output capacitor the output capacitor also needs to have low esr to keep low output voltage ripple. the output ripple voltage is: where i outmax is the maximum output current, k ripple is the ripple factor, r esr is the esr of the output capacitor, f sw is the switching frequency, l is the inductor value, and c out is the output capacitance. in the ca se of ceramic output capacitors, r esr is very small and does not contribute to the ripple. therefore, a lower capacitance value can be us ed for ceramic type. in the case of tantalum or electrolytic capacitors, the ripple is dominated by r esr multiplied by the ripple current. in that case, the output capacitor is chosen to have sufficiently low esr. for ceramic output capacitor, typically choose a capacitance of about 22f. for tantalum or electrolytic capacitors, choose a capacitor with less than 50m ? esr. rectifier diode use a schottky diode as the rectifier to conduct current when the high-side power switch is off. the schottky diode must have current rating higher than the maximum output current and a reverse voltage rating higher than the maximum input voltage. (5) pk lpk lim outmax i 2 1 i i _ _ =
act4513 rev 7, 14-nov-12 innovative power tm - 8 - www.active-semi.com copyright ? 2012 active-semi, inc. v out c out r comp c comp c comp2 c 2.5v 47 f ceramic cap 5.6k ? 3.3nf none 3.3v 47 f ceramic cap 6.2k ? 3.3nf none 5v 47 f ceramic cap 8.2k ? 3.3nf none 2.5v 470 f/6.3v/30m ? 39k ? 22nf 47pf 3.3v 470 f/6.3v/30m ? 45k ? 22nf 47pf 5v 470 f/6.3v/30m ? 51k ? 22nf 47pf ? ? ? ? ? ? ? ? ? out out 6 esrcout v 012 . 0 , c 10 1 . 1 min r (15) ( ? ) (16) comp esrcout out 2 comp r r c c = out out 5 comp c v 10 2 . 1 c ? = (f) (14) (13) (f) comp 5 comp r 10 8 . 1 c ? = (12) ( ? ) out out 8 c v 10 75 . 2 = v 808 . 0 g g 10 f c v 2 r comp ea sw out out comp = (11) comp2 comp 3 p c r 2 1 f = (10) (9) out out out 2 p c v 2 i f = (8) (7) comp vea out vdc g a i v 808 . 0 a = stability compensation figure 5: stability compensation c : c comp2 is needed only for high esr output capacitor the feedback loop of the ic is stabilized by the components at the comp pin, as shown in figure 3. the dc loop gain of the system is determined by the following equation: the dominant pole p1 is due to c comp : the second pole p2 is the output pole: the first zero z1 is due to r comp and c comp : and finally, the third pole is due to r comp and c comp2 (if c comp2 is used): the following steps should be used to compensate the ic: step 1. set the cross over frequency at 1/10 of the switching frequency via r comp : step 2. set the zero f z1 at 1/4 of the cross over frequency. if r comp is less than 15k ? , the equation for c comp is: if r comp is limited to 15k ? , then the actual cross over frequency is 3.4 / (v out c out ). therefore: step 3. if the output capacitor?s esr is high enough to cause a zero at lower than 4 times the cross over frequency, an additional compensation capacitor c comp2 is required. the condition for using c comp2 is: and the proper value for c comp2 is: though c comp2 is unnecessary when the output capacitor has sufficiently low esr, a small value c comp2 such as 100pf may improve stability against pcb layout parasitic effects. table 2 shows some calculated results based on the compensation method above. table 1: typical compensation for different output voltages and output capacitors c : c comp2 is needed for high esr output capacitor. c comp2 47pf is recommended. cc loop stability the constant-current control loop is internally compensated over the 750ma-2500ma output range. no additional external compensation is required to stabilize the cc current. output cable resistance compensation to compensate for resistive voltage drop across the charger's output cable, the act4513 integrates a simple, user-programmable cable voltage drop compensation using the impedance at the fb pin. use the curve in figure 4 to choose the proper feedback resistance values for cable compensation. comp vea ea 1 p c a 2 g f = comp comp 1 z c r 2 1 f =
act4513 rev 7, 14-nov-12 innovative power tm - 9 - www.active-semi.com copyright ? 2012 active-semi, inc. stability compensation cont?d r fb1 is the high side resistor of voltage divider. in the case of high r fb1 used, the frequency compensation needs to be adjusted correspondingly. as show in figure 7, adding a capacitor in paralled with r fb1 or increasing the compensation capacitance at comp pin helps the system stability. figure 6: cable compensation at various resistor divider values figure 7: frequency compensation for high r fb1 pc board layout guidance when laying out the printed circuit board, the following checklist should be used to ensure proper operation of the ic. 1) arrange the power components to reduce the ac loop size consisting of c in , in pin, sw pin and the schottky diode. 2) place input decoupling c eramic capacitor c in as close to in pin as possible. c in is connected power gnd with vias or short and wide path. 3) return fb, comp and iset to signal gnd pin, and connect the signal gnd to power gnd at a single point for best noise immunity. 4) use copper plane for power gnd for best heat dissipation and noise immunity. 5) place feedback resistor close to fb pin. 6) use short trace connecting hsb-c hsb -sw loop figure 8 shows an example of pcb layout. figure 9 and figure 10 give two typical car charger application schematics and associated bom list. delta output voltage vs. output current act4513-003 300 250 200 150 100 50 0 350 400 450 delta output voltage (mv) output current (a) 0 0.4 0.8 1.2 1.6 2 r f b 1 = 3 0 0 k r f b 1 = 2 4 0 k r f b 1 = 1 5 0 k r f b 1 = 2 0 0 k r f b 1 = 1 0 0 k r f b 1 = 3 6 0 k r f b 1 = 5 1 k r f b 1 = 4 30k figure 8: pcb layout
act4513 rev 7, 14-nov-12 innovative power tm - 10 - www.active-semi.com copyright ? 2012 active-semi, inc. figure 10: typical application circuit for 5v/1.5a car charger table 3: bom list for 5v/1.5a car charger item reference description manufacturer qty 1 u1 ic, act4513yh, sop-8ep active-semi 1 2 c1 capacitor, electrolytic, 47f/50v, 6.3 7mm murata, tdk 1 3 c2 capacitor, ceramic, 10f/50v, 1210, smd murata, tdk 1 4 c3 capacitor, ceramic, 2.2nf/6.3v, 0603, smd murata, tdk 1 5 c4 capacitor, ceramic, 10nf/50v, 0603, smd murata, tdk 1 8 l1 inductor,47h, 2.1a, 20% sumida 1 9 d1 diode, schottky, 40v/2a, sb240 diodes 1 10 d2 diode, 75v/150ma, ll4148 good-ark 1 11 r1 chip resistor, 16.2k ? , 0603, 1% murata, tdk 1 12 r2 chip resistor, 52k ? , 0603, 1% murata, tdk 1 13 r3 chip resistor, 8.2k ? , 0603, 5% murata, tdk 1 14 r4 chip resistor, 10k ? , 0603, 1% murata, tdk 1 6 c5 capacitor, electrolytic, 100f/10v, 6.3 7mm murata, tdk 1 7 c6 capacitor, ceramic, 1f/10v, 0603, smd murata, tdk 1
act4513 rev 7, 14-nov-12 innovative power tm - 11 - www.active-semi.com copyright ? 2012 active-semi, inc. typical performanc e characteristics (l = 33h, c in = 10f, c out = 47f, ta = 25c, r comp = 8.2k, c comp1 = 2.2nf, c comp2 = nc) act4513-004 efficiency (%) load current (ma) 200 600 1000 1400 1800 2200 100 85 80 75 70 65 60 95 90 efficiency vs. load current act4513-007 2200 2000 1900 1800 1700 1600 1500 2100 cc current (ma) temperature (c) 0 20 40 60 80 100 120 cc current vs. temperature act4513-008 cc current vs. input voltage cc current (ma) 1900 1800 1700 1600 1500 1400 input voltage (v) 10 14 18 22 26 34 30 act4513-009 maximum peak current vs. duty cycle maximum cc current (ma) 3.8 3.4 3.3 3.2 3.1 3 3.7 3.6 3.5 duty cycle 20 30 40 50 60 70 v in = 12v v in = 24v input voltage (v) 10 15 20 25 30 35 act4513-005 switching frequency vs. input voltage switching frequency (khz) 250 230 210 190 170 150 130 110 act4513-006 switching frequency vs. feedback voltage switching frequency (khz) 260 210 160 110 60 10 feedback voltage (mv) 0 100 200 300 400 500 600 700 800 900 v in = 12v v in = 24v v out = 5v
act4513 rev 7, 14-nov-12 innovative power tm - 12 - www.active-semi.com copyright ? 2012 active-semi, inc. typical performance ch aracteristics cont?d start up into cc mode sw vs. output voltage ripples start up into cc mode act4513-013 act4513-014 act4513-015 v out = 5v r lord = 1.5 ? i iset = 2a v in = 12v ch1: v out , 2v/div ch2: i out , 1a/div time: 200s/div ch1: v out , 2v/div ch2: i out , 1a/div time: 200s/div v in = 12v v out = 5v i out = 2a ch1 ch2 ch1: v out ripple, 20mv/div ch2: sw, 5v/div time: 2s/div v out = 5v r lord = 1.5 ? i iset = 2a v in = 24v ch1 ch2 ch1 ch2 (l = 33h, c in = 10f, c out = 47f, ta = 25 , r comp = 8.2k, c comp1 = 2.2nf, c comp2 = nc) shutdown current vs. input voltage act4513-010 130 120 110 100 90 80 70 shutdown current (a) input voltage (v) 10 15 20 25 30 35 40 act4513-011 standby current vs. input voltage standby supply current (ma) 3.6 3.2 2.8 2.4 2 1.6 1.2 0.8 0.4 0 input voltage (v) 0 4 8 12 16 20 24 28 32 36 40 act4513-012 reverse leakage current (v in floating) reverse leakage current (a) 160 120 80 40 0 v out (v) 0 1 2 3 4 5
act4513 rev 7, 14-nov-12 innovative power tm - 13 - www.active-semi.com copyright ? 2012 active-semi, inc. sw vs. output voltage ripple typical performance ch aracteristics cont?d (l = 33h, c in = 10f, c out = 47f, ta = 25 , r comp = 8.2k, c comp1 = 2.2nf, c comp2 = nc) act4513-016 act4513-017 start up with en act4513-018 load step waveforms act4513-019 short circuit act4513-020 act4513-021 v in = 24v v 0ut = 5v i 0ut = 2a ch1 ch2 ch1: v ripple , 20mv/div ch2: sw, 10v/div time: 2s/div v in = 12v v 0ut = 5v i 0ut = 2a ch1 ch2 ch1: en, 2v/div ch2: v out , 2v/div time: 400s//div start up with en ch1 ch2 ch1: en, 2v/div ch2: v out , 2v/div time: 400s//div v in = 12v v 0ut = 5v i iset = 2a ch1 ch2 ch1: v out , 200mv/div ch2: i out , 1a/div time: 200s/div load step waveforms ch1 ch2 ch1: v out , 200mv/div ch2: i out , 1a/div time: 200s/div v in = 12v v 0ut = 5v i iset = 2a ch1 ch2 ch1: v out , 2v/div ch2: i out , 1a/div time: 100s/div v in = 24v v 0ut = 5v i iset = 2a v in = 24v v 0ut = 5v i iset = 2a
act4513 rev 7, 14-nov-12 innovative power tm - 14 - www.active-semi.com copyright ? 2012 active-semi, inc. typical performance ch aracteristics cont?d act4513-022 short circuit v in = 24v v 0ut = 5v i iset = 2a ch1 ch2 ch1: v out , 2v/div ch2: i out , 1a/div time: 100s/div act4513-023 short circuit recovery v in = 12v v 0ut = 5v i iset = 2a ch1 ch2 ch1: v out , 2v/div ch2: i out , 2a/div time: 1ms/div act4513-024 short circuit recovery v in = 24v v 0ut = 5v i iset = 2a ch1 ch2 ch1: v out , 2v/div ch2: i out , 2a/div time: 1ms/div (l = 33h, c in = 10f, c out = 47f, ta = 25 , r comp = 8.2k, c comp1 = 2.2nf, c comp2 = nc)
act4513 rev 7, 14-nov-12 innovative power tm - 15 - www.active-semi.com copyright ? 2012 active-semi, inc. package outline sop-8ep package ou tline and dimensions symbol dimension in millimeters dimension in inches min max min max a 1.350 1.700 0.053 0.067 a1 0.000 0.100 0.000 0.004 a2 1.350 1.550 0.053 0.061 b 0.330 0.510 0.013 0.020 c 0.170 0.250 0.007 0.010 d 4.700 5.100 0.185 0.200 d1 3.202 3.402 0.126 0.134 e 3.800 4.000 0.150 0.157 e1 5.800 6.200 0.228 0.244 e2 2.313 2.513 0.091 0.099 e 1.270 typ 0.050 typ l 0.400 1.270 0.016 0.050 0 8 0 8 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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