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innovative power tm - 1 - www.active-semi.com copyright ? 2012 active-semi, inc. features ? 2a output current ? wide 4.5v to 18v operating input range ? synchronous buck topology ? integrated 130m ? power mosfet switches ? output adjustable from 0.923v to 12v ? up to 96% efficiency ? stable with low esr ceramic output capacitors ? internal soft start ? 1.5ma low standby input current ? high light load efficiency ? cycle-by-cycle over current limit ? input under voltage lockout ? hiccup protection at short circuit and over current ? low power loss at output short ? frequency fold back protection ? low power dissipation at over current and short circuit applications ? lcd-tv ? set-top box ? distributed power systems ? networking systems general description ACT4060B is a monolithic synchronous buck regulator. the device integrates two 130m ? mosfets, and provides 2a of continuous load current over a wide input voltage of 4.5v to 18v. current mode control provides fast transient response and cycle-by-cycle current limit. hiccup at short circuit reduces ic temperatures. an internal soft-start prevents inrush current at turn- on, and in shutdown mode t he supply current drops to 10 a. pulse-skipping mode at light load reduces standby power down to 1.5ma. this device, available in an 8-pin sop package, provides a very compact solution with minimal external components. ACT4060B 18v/2a step-down dc/dc converter rev 1, 23-may-12 ? efficiency vs. load current ACT4060B-001 efficiency (%) load current (ma) 10 100 1000 10000 80 75 70 65 60 55 85 90 95 100 v out = 5v v in = 7v v in = 12v v in = 18v
ACT4060B rev 1, 23-may-12 ? innovative power tm - 2 - www.active-semi.com copyright ? 2012 active-semi, inc. ordering information part number operation temperature range package pins packing ACT4060Bsh-t -40c to 85c sop-8 8 tape & reel pin configuration pin descriptions pin name description 1 hsb high-side bias input. this pin acts as the positive rail for the high-side switch's gate driver. connect a 10nf or greater capacitor between hsb and sw pins. 2 in input supply. bypass this pin to gnd with a lo w esr capacitor. drive in with a 4.5v to 18v power source. see input capacitor in the application information section. 3 sw switch output. connect this pin to the switch ing end of the external inductor. note that a capacitor is required from sw to hsb to power the high-side switch. 4 gnd ground. 5 fb feedback input. fb senses the output voltage to regulate that voltage. drive fb with a resistive voltage divider from the output voltage. the feedback threshold is 0.923v. see setting the output voltage . 6 comp compensation node. comp is used to comp ensate the regulation control loop. see compensation components. 7 en enable input. when higher than 2.5v, this pin turns the ic on. when lower than 2.3v, this pin turns ic off. when left unconnected, en is pulled up to logic high with a 2a pull-up current. en is a digital input t hat turns the regulator on or off. 8 n/c not connected.
ACT4060B rev 1, 23-may-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 + 20 v sw to gnd -1 to vin + 1 v hsb to gnd v sw - 0.3 to v sw + 6 v fb, en, comp to gnd -0.3 to + 6 v continuous sw current internally limited a junction to ambient thermal resistance 105 ? c/w maximum power dissipation 0.76 w operating junction temperature -40 to 150 ? c storage junction -55 to 150 ? c lead temperature (soldering 10 sec.) 300 ? c c : do not exceed these limits to prevent damage to the device. ex posure to absolute maximum rati ng conditions for long periods m ay affect device reliability.
ACT4060B rev 1, 23-may-12 ? innovative power tm - 4 - www.active-semi.com copyright ? 2012 active-semi, inc. parameter symbol test cond itions min typ max unit shutdown supply current v en = 0v 10 20 a supply current (no switching) v en = 3v, v fb = 1.2v 0.75 1.1 ma feedback voltage v fb 4.75v v in 18v 0.909 0.923 0.937 v error amplifier voltage gain a ea 400 v/v error amplifier transconductance g ea i c = 10 a 800 a/v high-side switch on resistance r ds(on)1 130 m ? low-side switch on resistance r ds(on)2 130 m ? upper switch current limit 50% duty cycle 3.5 a comp to current sense g cs 3.5 a/v oscillation frequency f sw 290 350 400 khz short circuit oscillation frequency 80 khz maximum duty cycle d max 88 % en lockout threshold voltage 2.4 2.6 2.8 v en lockout hysteresis 75 mv input under voltage lockout threshold input voltage rising 4.0 4.2 4.4 v internal soft startup time 2 ms hiccup frequency at short circuit 26 hz under voltage threshold 0.74 v thermal shutdown hysteresis window 30 c thermal shutdown 160 c input voltage 4.5 18 v electrical characteristics (v in = 12v, t a = 25c, unless otherwise specified.)
ACT4060B rev 1, 23-may-12 ? innovative power tm - 5 - www.active-semi.com copyright ? 2012 active-semi, inc. functional block diagram functional description as seen in function block diagram, the ACT4060B is peak current mode controlled synchronous buck converter. 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 and the low-side power switch turns on. the high-side power switch is driven by logic using hsb as the positive rail. this pin is charged to vsw + 5v when the low-side power switch turns on. the comp voltage is the integration of the error between fb input and the internal 0.923v reference. if fb is lower than the reference voltage, comp tends to go higher to increase current to the output to keep the output voltage regulated. the oscillator normally switches at 350khz. pulse skipping mode to decrease the power recycling at very light load, the low-side fet current is sensed to emulate a diode. when the low-side fet current decreases to zero, the fet is turned off to avoid negative inductor current. at no load and very light load, ACT4060B skips pulse automatically and thus achieve very high light load efficiency. with load increasing, ACT4060B goes into discontinuous current mode (dcm) and then continuous current mode (ccm). soft startup the ACT4060B builds in internal soft startup function. the internal fb reference voltage rises to steady state of 0.923v in 2ms to avoid inrush input current during startup. under voltage protection (uvp) at output short circuit or over current, the fb voltage is usually pulled low. to protect the ic at over current and short circuit, the ACT4060B builds in under voltage protection (uvp) function. when ACT4060B detects the fb voltage below 80% of the 0.923v reference, it pulls low comp voltage and discharges internal soft-start capacitor and goes into hiccup mode. the ic restarts in 32ms after going into hiccup mode. if the short circuit or over current is clear, the ic restarts back to normal mode. the uvp is disabled for 6ms starting from startup. if the output is short at startup, the output voltage never rises to nominal voltage. during the 6ms period of time, the output current is limited by cycle-by-cycle current limit. with 32ms shutdown period, the average input and output current at short circ uit is significantly reduced and the ic is more reliable.
ACT4060B rev 1, 23-may-12 ? innovative power tm - 6 - www.active-semi.com copyright ? 2012 active-semi, inc. secondary over current protection (socp) in normal operation, ACT4060B high-side fet current is protected by cy cle-by-cycle current limit. in some fault conditions, the input current may run away. socp current limit is set 30% higher than cycle-by-cycle current limit, and once socp is triggered, ACT4060B goes into hiccup mode and reduce the power dissipation significantly. enable pin the ACT4060B has an enable input en for turning the ic on or off. the en pin contains a precision 2.5v comparator with 75mv hysteresis and a 1.3 a 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. if left floating, the en pin will be pulled up to roughly 5v by the internal 1.3 a current source. it can be driven from standard logic signals greater than 2.5v, or driven with open-drain logic to provide digital on/off control. thermal shutdown the ACT4060B disables switching when its junction temperature exceeds 160c and resumes when the temperature has dropped by 30c.
ACT4060B rev 1, 23-may-12 ? innovative power tm - 7 - www.active-semi.com copyright ? 2012 active-semi, inc. 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: table 1: recommended resistance values 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 = 20~40% to correspond to the peak-to-peak inductor ripple current being 20~40% 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: 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 3.5a, as shown in electrical characteristics table. (1) ? ? ? ? ? ? ? = 1 923 . 0 2 1 v v r r out fb 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) (5) pk lpk lim outmax i 2 1 i i _ _ = v out r1 r2 5.0v 47k ? 10.5k ? 3.3v 27.4k ? 10.5k ? 2.5v 18k ? 10.5k ? 1.8v 10.2k ? 10.5k ? 1.2v 3.3k ? 10.5k ? 1.0v 1k ? 10.5k ? table 2: inductor values range and typical compensation v out v in l c out r comp c comp c comp2 5.0v 7v ~ 18v 10h ~ 33h 330f/10v 25k ? 2.2nf 220pf 22f/ ceramic 2 10k ? 2.2nf n/a 3.3v 5v ~ 18v 8.2h ~ 22h 330f/10v 21k ? 2.2nf 220pf 22f/ ceramic 2 8.2k ? 2.2nf n/a 1.8v 4.5v ~ 18v 5.6h ~ 15h 470f/10v 12k ? 4.7nf 220pf 22f/ ceramic 2 8.2k ? 4.7nf n/a 1.2v 4.5v ~ 16v 4h ~ 12h 470f/10v 12k ? 10nf 220pf 22f/ ceramic 2 8.2k ? 10nf n/a 4.5v ~ 13v 3.3h ~ 10h 470f/10v 10k ? 10nf 220pf 22f/ ceramic 2 8.2k ? 10nf n/a 1.0v
ACT4060B rev 1, 23-may-12 ? innovative power tm - 8 - 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 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 2: 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 can 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 case of ceramic output capacitors, r esr is very small and does not contribute to the ripple. therefore, a lower capacitance value can be used 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. optional schottky diode during the transition between high-side switch and low-side switch, the body diode of the low-side power mosfet conducts the inductor current. the forward voltage of this body diode is high. an optional schottky diode may be paralleled between the sw pin and gnd pin to improve overall efficiency.
ACT4060B rev 1, 23-may-12 ? innovative power tm - 9 - www.active-semi.com copyright ? 2012 active-semi, inc. 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 both the ac loop and dc loop size. ac loop includes input cap, v in pin and v in ground pin, dc loop includes sw pin, inductor, output capacitor and ground pin. 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 3 shows an example of pcb layout. figure 4 and figure 5 give two typical car charger application schematics and associated bom list. figure 3: pcb layout
ACT4060B rev 1, 23-may-12 ? innovative power tm - 10 - www.active-semi.com copyright ? 2012 active-semi, inc. figure 4: typical application circuit for 1.8v/2a dc-dc converter table 3: bom list for 1.8v/2a dc-dc converter item reference description manufacturer qty 1 u1 ic, ACT4060Bsh, sop-8 active-semi 1 2 c1 capacitor, ceramic, 10f/25v, 1210, smd murata, tdk 1 3 c2 capacitor, ceramic, 6.8nf/6.3v, 0603, smd murata, tdk 1 4 c3 capacitor, ceramic, 10nf/25v, 0603, smd murata, tdk 1 5 c4,c5 capacitor, ceramic, 47f/10v, 1206, smd murata, tdk 2 6 l1 inductor,10h, 3a, 20%, smd tyco electronics 1 7 r1 chip resistor, 10k ? , 0603, 1% murata, tdk 1 8 r2 chip resistor, 10.5k ? , 0603, 1% murata, tdk 1 9 r3 chip resistor, 6.8k ? , 0603, 5% murata, tdk 1
ACT4060B rev 1, 23-may-12 ? innovative power tm - 11 - www.active-semi.com copyright ? 2012 active-semi, inc. figure 5: typical application circuit for 5v/2a dc-dc converter table 4: bom list for 5v/2a dc-dc converter item reference description manufacturer qty 1 u1 ic, ACT4060Bsh, sop-8 active-semi 1 2 c1 capacitor, ceramic, 10f/50v, 1210, smd murata, tdk 1 3 c2 capacitor, ceramic, 6.8nf/6.3v, 0603, smd murata, tdk 1 4 c3 capacitor, ceramic, 10nf/50v, 0603, smd murata, tdk 1 5 c4,c5 capacitor, ceramic, 22f/10v, 1206, smd murata, tdk 2 6 l1 inductor, 22h, 3a, 20% sumida 1 7 d1 diode, 75v/150ma, ll4148 good-ark 1 8 r1 chip resistor, 47k ? , 0603, 1% murata, tdk 1 9 r2 chip resistor, 10.5k ? , 0603, 1% murata, tdk 1 10 r3 chip resistor, 8.2k ? , 0603, 5% murata, tdk 1
ACT4060B rev 1, 23-may-12 ? innovative power tm - 12 - www.active-semi.com copyright ? 2012 active-semi, inc. typical performanc e characteristics (l = 22h, c in = 100f, c out = 330f, ta = 25c, r comp = 15k, c comp1 = 2.2nf, c comp2 = n/c) ACT4060B-005 0.94 0.93 0.92 0.91 0.9 0.95 fb voltage (v) fb voltage vs. load current ACT4060B-006 fb voltage vs. ic temperature fb voltage (v) 0.926 0.923 0.92 0.917 0.914 0.911 0.929 0.932 temperature (c) 20 40 60 80 100 120 140 160 ACT4060B-007 shutdown current vs. v in current (a) 21 18 15 12 9 6 3 0 24 v in voltage (v) 5 7 9 11 13 17 15 19 21 ACT4060B-003 frequency vs. v in frequency (khz) 420 400 380 360 340 320 300 280 ACT4060B-004 frequency vs. fb voltage frequency (khz) 250 200 150 100 50 0 300 350 400 fb voltage (v) 0 200 400 600 800 1000 load current (ma) 0 400 800 1200 1600 2000 v in voltage (v) 2 4 6 8 10 14 12 16 20 22 18 ACT4060B-002 efficiency (%) load current (ma) 10 100 1000 10000 80 75 70 65 60 55 85 90 95 100 v out = 5v v in = 7v v in = 12v v in = 18v efficiency vs. load current
ACT4060B rev 1, 23-may-12 ? innovative power tm - 13 - www.active-semi.com copyright ? 2012 active-semi, inc. typical performance ch aracteristics cont?d 10ma load operation 100ma load operation no load operation ACT4060B-011 ACT4060B-012 ACT4060B-013 ch1: v ripple , 10mv/div ch2: sw, 5v/div ch3: i l , 200ma/div time: 10s/div ch1: v ripple , 20mv/div ch2: sw, 5v/div ch3: i l , 1a/div time: 2s/div ch1 ch2 ch1 ch2 ch1 ch2 standby current vs. v in ACT4060B-008 3 2.5 2 1.5 1 0.5 0 standby current (ma) v in voltage (v) 3 5 7 9 11 13 15 17 19 21 ACT4060B-009 i in vs. v in at output dead short i in (ma) 140 120 100 80 60 40 20 v in (v) 4 6 8 10 12 14 16 18 20 ACT4060B-010 peak current limit vs. duty cycle peak current (a) 3.2 3.0 2.8 2.6 2.4 3.4 3.6 duty cycle 20 30 40 50 60 70 80 90 (l = 22h, c in = 100f, c out = 330f, ta = 25c, r comp = 15k, c comp1 = 2.2nf, c comp2 = n/c) v in = 12v v 0ut = 5v v in = 12v v 0ut = 5v v in = 12v v 0ut = 5v ch3 ch3 ch1: v ripple , 20mv/div ch2: sw, 5v/div ch3: i l , 1a/div time: 2s/div ch3
ACT4060B rev 1, 23-may-12 ? innovative power tm - 14 - www.active-semi.com copyright ? 2012 active-semi, inc. 2a load operation typical performance ch aracteristics cont?d ACT4060B-014 ACT4060B-015 load transient (0a~1a) ACT4060B-016 start up with v in (load 0a) ACT4060B-017 start up with en (load 0a) ACT4060B-018 ACT4060B-019 ch1 ch2 ch1 ch2 ch1: v out , 50mv/div ch2: i load , 500ma/div time: 4ms//div load transient (1a~2a) ch1 ch2 ch1 ch2 ch1: v in , 10v/div ch2: v out , 5v/div ch3: sw, 10v/div ch4: i l , 2a/div time: 2ms/div start up with v in (load 2a) ch1 ch2 ch1 ch2 (l = 22h, c in = 100f, c out = 330f, ta = 25c, r comp = 15k, c comp1 = 2.2nf, c comp2 = n/c) v in = 12v v 0ut = 5v v in = 12v v 0ut = 5v v in = 12v v 0ut = 5v v in = 12v v 0ut = 5v v in = 12v v 0ut = 5v v in = 12v v 0ut = 5v ch3 ch1: v ripple , 50mv/div ch2: sw, 5v/div ch3: i l , 1a/div time: 2s/div ch1: v out , 50mv/div ch2: i load , 500ma/div time: 4ms//div ch3 ch4 ch3 ch4 ch1: v in , 10v/div ch2: v out , 5v/div ch3: sw, 10v/div ch4: i l , 2a/div time: 2ms/div ch3 ch4 ch1: en, 5v/div ch2: v out , 5v/div ch3: sw, 10v/div ch4: i l , 2a/div time: 2ms/div
ACT4060B rev 1, 23-may-12 ? innovative power tm - 15 - www.active-semi.com copyright ? 2012 active-semi, inc. typical performance ch aracteristics cont?d ACT4060B-020 start up with en (load 2a) ch1 ch2 ACT4060B-021 short circuit ch1 ch2 ch1: i out , 10a/div ch2: v out , 5v/div ch3: sw, 10v/div ch4: i l , 5a/div time: 20ms/div (l = 22h, c in = 100f, c out = 330f, ta = 25c, r comp = 15k, c comp1 = 2.2nf, c comp2 = n/c) v in = 12v v 0ut = 5v v in = 12v v 0ut = 5v ACT4060B-022 short circuit recovery ch1 ch2 v in = 12v v 0ut = 5v ACT4060B-023 start up with output dead short ch1 ch2 v in = 12v v 0ut = 5v ch1: en, 5v/div ch2: v out , 5v/div ch3: sw, 10v/div ch4: i l , 2a/div time: 2ms/div ch3 ch4 ch3 ch4 ch1: i out , 5a/div ch2: v out , 5v/div ch3: sw, 10v/div ch4: i l , 5a/div time: 20ms/div ch3 ch4 ch3 ch4 ch1: en, 5v/div ch2: i out , 5a/div ch3: sw, 10v/div ch4: i l , 5a/div time: 20ms/div
ACT4060B rev 1, 23-may-12 ? innovative power tm - 16 - www.active-semi.com copyright ? 2012 active-semi, inc. package outline sop-8 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. a a2 a1 l ? c e d e1 b e symbol dimension in millimeters dimension in inches min max min max a 1.350 1.750 0.053 0.069 a1 0.100 0.250 0.004 0.010 a2 1.350 1.550 0.053 0.061 b 0.330 0.510 0.013 0.020 c 0.190 0.250 0.007 0.010 d 4.700 5.100 0.185 0.201 e 3.800 4.000 0.150 0.157 e1 5.800 6.300 0.228 0.248 e 1.270 typ 0.050 typ l 0.400 1.270 0.016 0.050 0 8 0 8

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