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preliminary datasheet 3a, 2mhz high performance synchr onous buck converter AP3433 jul. 2012 rev. 1. 1 bcd semiconductor manufacturing limited 1 general description the AP3433 is a current mode, pwm synchronous buck (step-down) dc-dc converter, capable of driving a 3a load with high e fficiency, excellent line and load regulation. the device integrates two n-channel power mosfets with low on-res istance. current mode control provides fast transient response and cycle-by-cycle current limit. the switching frequency of AP3433 can be programmable from 300khz to 2mhz, which allows small-sized components, such as capacitors and inductors. a standard series of inductors from several different manufacturers are available. this feature greatly simplifies the design of switch-mode power supplies. under voltage lockout is internally set at 2.6v, but can be increased by programming the threshold with a resistor network on the enable pin. the output voltage startup ramp is controlled by the soft-start pin. an open drain power good signal indicates the output is within 93% to 107% of its nominal voltage. the AP3433 is available in qfn-33-16 package. features ? input voltage range: 2.95v to 5.5v ? 0.827v reference voltage with 3% precision ? two 45m ? (typical) mosfets for high efficiency at 3a load ? high efficiency: up to 94% ? output current: 3a ? programmable frequency:300khz to 2mhz ? current mode control ? synchronizes to external clock ? adjustable soft-start ? soft start-up into pre-biased output ? uv and ov power good output ? built-in over current protection ? built-in thermal shutdown function ? programmable uvlo function ? built-in over voltage protection ? thermally enhanced 3mm3mm 16-pin qfn applications ? low-voltage, high-density power systems ? point of load regulation for consumer applications such as set top boxes, lcd displays, cpe equipment figure 1. package type of AP3433 qfn-33-16
preliminary datasheet 3a, 2mhz high performance synchr onous buck converter AP3433 jul. 2012 rev. 1. 1 bcd semiconductor manufacturing limited 2 pin configuration fn package (qfn-33-16) vin vin gnd gnd ss sw sw sw ep 5678 1 2 3 49 12 pin 1 mark 11 10 13 14 15 16 figure 2. pin configurat ion of AP3433 (top view) pin description pin number pin name function 1,2,16 vin supply input pin. a capacitor should be connected between the vin and gnd pin to keep the dc input voltage constant 3,4 gnd power ground. this pin should be electri cally connected to the power pad under the ic 5 agnd analog ground. this pin should be electr ically connected to gnd close to the device 6 fb feedback pin. inverting node of the transconductance error amplifier 7 comp compensation pin. this pin is the output of the transconductance error amplifier and the input to the current comparator. connect external compensation elements to this pin to stabilize the control loop 8 rt/clk resistor timing or external clock input pin 9 ss soft-start pin. an external capacitor connected to this pin sets the output voltage rise time. this pin can also be used for tracking 10,11,12 sw internal power switch output pin. this pin is connected to the inductor and bootstrap capacitor 13 boot bootstrap pin. a bootstrap capacitor is connected between the boot pin and sw pin. the voltage across the bootstrap capacitor drives th e internal high-side power mosfet 14 pgd power good indicator output. asserts low if output voltage is low due to thermal shutdown, over-current, over/und er-voltage or en shut down 15 en enable pin, internal pull-up current source . pull below 1.2v to disable. float to enable. can be used to set the on/off th reshold (adjust uvlo) with two additional resistors
preliminary datasheet 3a, 2mhz high performance synchr onous buck converter AP3433 jul. 2012 rev. 1. 1 bcd semiconductor manufacturing limited 3 functional block diagram figure 3. functional block diagram of AP3433 ordering information AP3433 - circuit type package fn: qfn-3 3-16 package temperature range part number marking id packing type qfn-33-16 -40 to 85oc AP3433fntr-g1 b1d tape & reel bcd semiconductor's pb-free products, as designated with "g1" suffix in the part number, are rohs compliant and green. g1: green tr: tape & reel
preliminary datasheet 3a, 2mhz high performance synchr onous buck converter AP3433 jul. 2012 rev. 1. 1 bcd semiconductor manufacturing limited 4 absolute maximum ratings (note 1) parameter symbol value unit vin pin voltage v in -0.3 to 6.5 v en pin voltage v en -0.3 to 6.5 v sw pin voltage v sw -0.3 to v in +0.3 v fb pin voltage v fb -0.3 to 6.5 v comp pin voltage v comp -0.3 to 6.5 v pgd pin voltage v pgd -0.3 to 6.5 v rt/clk pin voltage v rt/clk -0.3 to 6.5 v ss pin voltage v ss -0.3 to 6.5 v thermal resistance (junction to ambient) ja 70 oc/w thermal resistance (junction to case) jc (bottom) note 1: stresses greater than those listed under ?absolute maximum ratings? may cause permanent damage to the device. these are stress ratings only, and functional op eration of the device at these or any other conditions beyond those indicated under ?recommended operating co nditions? is not implied. exposure to ?absolute maximum ratings? for extended periods may affect device reliability. recommended operating conditions parameter symbol min max unit input voltage v in 2.95 5.5 v maximum output current i out(max) 3 a operating ambient temperature t a -40 85 oc
preliminary datasheet 3a, 2mhz high performance synchr onous buck converter AP3433 jul. 2012 rev. 1. 1 bcd semiconductor manufacturing limited 5 electrical characteristics v in =2.95 to 5.5v, t a =25oc, unless otherwise specified. specifications with boldface type apply over full operating temperature range from -40 to 85oc. parameters symbol condi tions min typ max unit supply voltage (vin pin) input voltage v in 2.95 5.5 v quiescent current i q v fb =0.9v,v in =5v, t a =25 c, r t =400k ? 360 575 a shutdown supply current i shdn v en =0v,t a =25 c 2.95v v in 5.5v 2 5 a enable and uvlo (en pin) enable threshold v en_h rising 1.16 1.25 1.37 v v en_l falling 1.18 v internal under voltage lockout threshold v uvlo 2.6 2.8 v internal under voltage hysteresis v hys 150 mv voltage reference (fb pin) voltage reference v ref 2.95v v in 5.5v 0.802 0.827 0.852 v mosfet high side switch on-resistance r on_h v boot-sw =5v 45 81 m ? v boot-sw =2.95v 64 110 m ? low side switch on-resistance r on_l v in =5v 42 81 m ? v in =2.95v 59 110 m ? current limit current limit threshold i limit 4.2 6.6 a thermal shutdown thermal shutdown t tsd 140 c hysteresis 20 c
preliminary datasheet 3a, 2mhz high performance synchr onous buck converter AP3433 jul. 2012 rev. 1. 1 bcd semiconductor manufacturing limited 6 electrical characteristics (continued) v in =2.95 to 5.5v, t a =25oc, unless otherwise specified. specifications with boldface type apply over full operating temperature range from -40 to 85oc. parameters symbol condi tions min typ max unit timing resistor and external clock (rt/clk pin) switching frequency range (rt mode) 300 2000 khz switching frequency range (clk mode) 300 2000 khz switching frequency f s r t =400k ? 400 500 600 khz minimum clk pulse width 75 ns rt/clk voltage r t =400k ? 0.5 v rt/clk high threshold 1.6 2.2 v rt/clk low threshold 0.4 0.6 v boot (boot pin) boot charge resistor r boot v in =5v 16 ? boot-sw uvlo v in =2.95v 2.2 v soft start (ss pin) charge current i ss v ss =0.4 2.2 a ss to reference crossover v ss 98% nominal 1.1 v power good (pgd pin) feedback threshold v fb_th v fb falling (fault) 91 %v ref v fb rising (good) 93 v fb rising (fault) 107 v fb falling (good) 105
preliminary datasheet 3a, 2mhz high performance synchr onous buck converter AP3433 jul. 2012 rev. 1. 1 bcd semiconductor manufacturing limited 7 typical performance characteristics figure 4. supply current vs. input voltage figure 5. supply current vs. temperature figure 6. efficiency vs. output current figure 7.uvlo threshold vs. temperature 2.7 3.0 3.3 3.6 3.9 4.2 4.5 4.8 5.1 5.4 5.7 360 365 370 375 380 385 390 395 400 405 410 415 420 425 430 supply current ( a) input voltage (v) -50 -25 0 25 50 75 100 125 150 370 380 390 400 410 420 430 440 450 460 470 v in =5v v fb =0.9v supply current ( a) temperature ( o c) 0 300 600 900 1200 1500 1800 2100 2400 2700 3000 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 efficiency (%) output current (ma) v out =1.8v v in =3.3v v in =5v -50 -25 0 25 50 75 100 125 150 2.10 2.15 2.20 2.25 2.30 2.35 2.40 2.45 2.50 2.55 2.60 uvlo threshold (v) temperature ( o c) start switching stop switching
preliminary datasheet 3a, 2mhz high performance synchr onous buck converter AP3433 jul. 2012 rev. 1. 1 bcd semiconductor manufacturing limited 8 typical performance characteristics (continued) figure 8. switching frequency vs. temper ature figure 9. reference voltage vs. temperature figure 10. switching frequency vs. rt resistance figure 11. switching frequency vs. rt resistance low frequency range high frequency range -50 -25 0 25 50 75 100 125 150 900 910 920 930 940 950 960 970 980 990 1000 1010 1020 r t =180k switching frequency (khz) temperature ( o c) -50 -25 0 25 50 75 100 125 150 0.816 0.818 0.820 0.822 0.824 0.826 0.828 0.830 0.832 0.834 reference voltage (v) temperature ( c) 300 400 500 600 700 800 900 1000 100 200 300 400 500 600 700 800 switching frequency (khz) rt resistance (k ? ) 80 100 120 140 160 180 200 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 switching frequency (khz) rt resistance (k ? )
preliminary datasheet 3a, 2mhz high performance synchr onous buck converter AP3433 jul. 2012 rev. 1. 1 bcd semiconductor manufacturing limited 9 typical performance characteristics (continued) time 4ms/div time 20 s/div time 200 s/div time 400ns/div v out(ac) 200mv/div figure 14. load transient response figure 15. synchronizing to external clock (v in =5v, v out =1.8v, i out =0 to 3a) (f clock =2mhz) i out 2a/div v clock 2v/div v sw 2v/div v out 1v/div v in 2v/div i l 2a/div v ss 2v/div figure 12. start up from v in (v in =5v, v out =1.8v, i out =3a) figure 13. disable ic (v in =5v, v out =1.8v, i out =3a) v en 2v/div v out 1v/div v ss 2v/div i l 2a/div
preliminary datasheet 3a, 2mhz high performance synchr onous buck converter AP3433 jul. 2012 rev. 1. 1 bcd semiconductor manufacturing limited 10 typical performance characteristics (continued) time 4ms/div time 4ms/div figure 16. short circuit protection figure 17. short circuit recovery (v in =5v, v out =1.8v, i out =3a) (v in =5v, v out =1.8v, i out =3a) v out 1v/div v ss 2v/div v comp 0.5v/div i l 2a/div v out 1v/div v ss 2v/div v comp 0.5v/div i l 2a/div
preliminary datasheet 3a, 2mhz high performance synchr onous buck converter AP3433 jul. 2012 rev. 1. 1 bcd semiconductor manufacturing limited 11 typical application figure 18. typical application of AP3433
preliminary datasheet 3a, 2mhz high performance synchr onous buck converter AP3433 jul. 2012 rev. 1. 1 bcd semiconductor manufacturing limited 12 mechanical dimensions qfn-33-16 unit:mm(inch)
important notice bcd semiconductor manufacturing limited reserves the right to make changes without further not ice to any products or specifi- cations herein. bcd semiconductor manufacturing limited does not as sume any responsibility for us e of any its products for any particular purpose, nor does bcd semiconductor manufacturi ng limited assume any liability aris ing out of the application or use of any its products or circui ts. bcd semiconductor manufacturing limited does not convey any license under its patent rights or other rights nor the rights of others. - wafer fab shanghai sim-bcd semiconductor manufacturing co., ltd. 800 yi shan road, shanghai 200233, china tel: +86-21-6485 1491, fax: +86-21-5450 0008 main site regional sales office shenzhen office shanghai sim-bcd semiconductor manuf acturing co., ltd., shenzhen office unit a room 1203, skyworth bldg., gaoxin ave.1.s., nanshan district, shenzhen, china tel: +86-755-8826 7951 fax: +86-755-8826 7865 taiwan office bcd semiconductor (taiwan) company limited 4f, 298-1, rui guang road, nei-hu district, taipei, taiwan tel: +886-2-2656 2808 fax: +886-2-2656 2806 usa office bcd semiconductor corp. 30920 huntwood ave. hayward, ca 94544, usa tel : +1-510-324-2988 fax: +1-510-324-2788 - headquarters bcd semiconductor manufacturing limited no. 1600, zi xing road, shanghai zizhu sc ience-based industrial park, 200241, china tel: +86-21-24162266, fax: +86-21-24162277 bcd semiconductor manufacturing limited important notice bcd semiconductor manufacturing limited reserves the right to make changes without further not ice to any products or specifi- cations herein. bcd semiconductor manufacturing limited does not as sume any responsibility for us e of any its products for any particular purpose, nor does bcd semiconductor manufacturi ng limited assume any liability aris ing out of the application or use of any its products or circui ts. bcd semiconductor manufacturing limited does not convey any license under its patent rights or other rights nor the rights of others. - wafer fab shanghai sim-bcd semiconductor manufacturing limited 800, yi shan road, shanghai 200233, china tel: +86-21-6485 1491, fax: +86-21-5450 0008 bcd semiconductor manufacturing limited main site regional sales office shenzhen office shanghai sim-bcd semiconductor manuf acturing co., ltd. shenzhen office advanced analog circuits (shanghai) corporation shenzhen office room e, 5f, noble center, no.1006, 3rd fuzhong road, futian district, shenzhen 518026, china tel: +86-755-8826 7951 fax: +86-755-8826 7865 taiwan office bcd semiconductor (taiwan) company limited 4f, 298-1, rui guang road, nei-hu district, taipei, taiwan tel: +886-2-2656 2808 fax: +886-2-2656 2806 usa office bcd semiconductor corporation 30920 huntwood ave. hayward, ca 94544, u.s.a tel : +1-510-324-2988 fax: +1-510-324-2788 - ic design group advanced analog circuits (shanghai) corporation 8f, zone b, 900, yi shan road, shanghai 200233, china tel: +86-21-6495 9539, fax: +86-21-6485 9673 bcd semiconductor manufacturing limited http://www.bcdsemi.com bcd semiconductor manufacturing limited

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