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data sheet 3a, 1.25mhz high performance synchronous buck converter AP3436/a jan. 2013 rev. 1.2 bcd semiconductor manufacturing limited 1 general description the AP3436/a is a step-down dc-dc converter with integrated power stage capable of driving up to 3a continuous output current. it integrates 2 n-channel power mosfets with low on-resistance. current mode control provides fast transient response and cycle-by-cycle current limit. for AP3436, the regulator adopts current-mode in forced pulse-width modulation (pwm) mode with 1.25mhz switching frequency internally, which allows small-sized components, such as capacitors and inductors. this feature greatly simplifies the design of switch-mode power supplies. under pwm mode, the device remains at the fixed pwm operation (typical at 1.25mhz), regardless of if the load current is high or low. for AP3436a, the regulator operates in either fixed pwm mode or a pulse-skipping modulation (psm) mode depending on the different load conditions. the device can operate at typical 1.25mhz fixed switching frequency under heavy load condition. at light load, the regulator enters a psm mode to minimize the switching loss by reducing the switching frequency. the AP3436/a provides en function. pulling this pin high statically enables the device while pulling the pin low statically for longer than 10s will shut it down. under voltage lockout is internally set at 2.75v for v cc detection. the output voltage startup ramp is controlled by the soft start. an open drain power good signal indicates the output is within 75% to 125% of its nomin al voltage. the AP3436/a is available in dfn-33-10 package. features ? analog power input v cc range: 3.0v to 5.5v ? power input v in range: 1.3v to 5.5v ? 0.6v reference voltage with 1.5% precision ? 2 mosfets (typ 50m ? ) for high efficiency at 3a loads ? high efficiency: up to 95% ? output current: 3a ? current mode control ? built-in soft start function ? uv and ov power good output ? built-in uv and ov protection function ? built-in over current protection ? built-in thermal shutdown function ? thermally enhanced 3mm3mm dfn package applications ? desktop & notebook ? low voltage, high density power system ? consumer application such as set top box, lcd display and cpe equipment figure 1. package type of AP3436/a dfn-33-10
data sheet 3a, 1.25mhz high performance synchronous buck converter AP3436/a jan. 2013 rev. 1.2 bcd semiconductor manufacturing limited 2 pin configuration dn package (dfn-33-10) pin 1 mark 1 2 3 4 56 7 8 9 10 figure 2. pin configuratio n of AP3436/a (top view) pin description pin number pin name function 1 fb voltage feedback input. connect to v out through a voltage divider to set the output voltage 2 vcc analog power input 3 vin power input 4, 5 gnd ground. must be connected to gnd on pcb 6, 7 sw power switch output 8 boot high side switch driver supply 9 pgood open drain power good output 10 en enable 11 exposed pad thermal connection to the pcb. must be connected to gnd on pcb
data sheet 3a, 1.25mhz high performance synchronous buck converter AP3436/a jan. 2013 rev. 1.2 bcd semiconductor manufacturing limited 3 functional block diagram 75% logic 125% ea voltage reference soft start en shutdown logic thermal shutdown uvlo boot charge boot uvlo logic and pwm latch pwm slope compensation oscillator current limit and short protection current sense fb 1 2 vcc 9 10 pgood en gnd gnd sw boot 3 vin 8 6,7 4,5 4,5 + figure 3. functional block diagram of AP3436/a ordering information AP3436 - circuit type blank: AP3436 a: AP3436a package temperature range function part number marking id packing type dfn-3 3-10 -40 to 85c pwm AP3436dntr-g1 bdb tape & reel pwm/psm AP3436adntr-g1 bdf bcd semiconductor's pb-free products, as designated wi th "g1" in the part number, are rohs compliant and green. package dn: dfn-33-10 g1: green tr: tape & reel
data sheet 3a, 1.25mhz high performance synchronous buck converter AP3436/a jan. 2013 rev. 1.2 bcd semiconductor manufacturing limited 4 absolute maximum ratings (note 1) parameter symbol value unit vcc, vin pin voltage v cc, v in -0.3 to 6 v en pin voltage v en -0.3 to 6 v sw pin voltage v sw -0.3 to v in +0.3 v sw pin transient voltage (<50ns) v sw_transient -5 to v in +5 v fb pin voltage v fb -0.3 to 6 v pgood pin voltage v pgd -0.3 to 6 v boot to sw voltage v boot_sw 0 to 6 v thermal resistance (junctio n to ambient, simulation) ja 33 oc/w operating junction temperature t j -40 to 150 oc storage temperature t stg -65 to 150 oc lead temperature (soldering, 10sec) t lead 260 oc esd (human body model) v hbm 2000 v esd (machine model) v mm 200 v 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 analog input voltage v cc 3.0 5.5 v power input voltage v in 1.3 5.5 v maximum output current i out(max) 3 a output voltage v out 0.8 v in v operating ambient temperature t a -40 85 oc
data sheet 3a, 1.25mhz high performance synchronous buck converter AP3436/a jan. 2013 rev. 1.2 bcd semiconductor manufacturing limited 5 electrical characteristics v cc =5v, v in =5v, t a =25c, unless otherwise specified. parameter symbol conditions min typ max unit supply voltage (vcc, vin pin) analog power input voltage v cc 3.0 5.5 v power input voltage v in 1.3 5.5 v quiescent current i q v fb =1.5v, v cc =5v, v in =5v 400 a shutdown supply current i shdn v en =0v, 3.0v v cc 5.5v, 1.3v v in 5.5v 1 a power on reset internal under voltage lockout threshold for v cc v uvlo 2.75 2.85 v internal under voltage hysteresis for v cc v hys_vcc 150 mv voltage reference (fb pin) voltage reference v fb 3.0v v cc 5.5v 0.591 0.600 0.609 v internal pwm frequency pwm frequency f 3.0v v cc 5.5v 1.0 1.25 1.5 mhz mosfet spec high side switch on-resistance r on_h v boot_sw =5.0v 50 100 m ? v boot_sw =3.0v 70 140 m ? low side switch on-resistance r on_l v cc =5.0v 50 100 m ? v cc =3.0v 70 140 m ? current limit current limit threshold i limit 4.8 7.6 a thermal shutdown thermal shutdown t tsd 160 c hysteresis 20 c boot spec (boot pin) boot charge resistor r boot v cc =5.0v 16 ? boot to sw uvlo v cc =3.0v 2.2 v soft start soft start time t ss 0.8 2 ms
data sheet 3a, 1.25mhz high performance synchronous buck converter AP3436/a jan. 2013 rev. 1.2 bcd semiconductor manufacturing limited 6 electrical characteristics (continued) v cc =5v, v in =5v, t a =25c, unless otherwise specified. parameter symbol conditions min typ max unit enable (en pin) en pin threshold v en_l 0.8 v v en_h 1.6 v power good (pgood pin) feedback threshold v fbth v fb falling (fault) 70 75 %v ref v fb rising (good) 77 82 v fb rising (fault) 125 130 v fb falling (good) 118 123 delay time for pgood from high to low t pg_dly 30 s internal power good pull low resistance r pg 150 ? external pull-up resistance range r pg_up 3000 ? system performance output under voltage protection threshold v uvp v in =1.3 to 5.5v 0.5 v out v delay time for uvp triggered t uvp v in =1.5 to 5v 65 s output over voltage protection threshold v ovp v in =1.3 to 5.5v 1.5 v out v delay time for ovp triggered t ovp v in =1.5 to 5v 65 s output current i out v in =1.5 to 5v, v out =1.0v 3 a output voltage line regulation v in =1.5 to 5v, i out =100ma 0.4 % v out /v output voltage load regulation i out =0a to 3a 0.3 % v out /a output voltage load transient v tran v in =5v, v out =1.0v, di/dt=400ma/ s 2.5 % v out /a efficiency v cc =5v, v in =5v, i out =3a, v out =1.2v 80 %
data sheet 3a, 1.25mhz high performance synchronous buck converter AP3436/a jan. 2013 rev. 1.2 bcd semiconductor manufacturing limited 7 typical performance characteristics figure 4. efficiency vs. output current figure 5. reference voltage vs. input voltage figure 6. reference voltage vs. temperature figure 7. pwm frequency vs. input voltage -40 -20 0 20 40 60 80 100 120 140 0.56 0.57 0.58 0.59 0.60 0.61 0.62 0.63 0.64 reference voltage(v) temperature ( o c) v in =v cc =5.0v 3.00 3.25 3.50 3.75 4.00 4.25 4.50 4.75 5.00 5.25 5.50 1.00 1.05 1.10 1.15 1.20 1.25 1.30 1.35 1.40 1.45 1.50 pwm frequency (mhz) input voltage (v) v cc =v in =v en 0.00 0.25 0.50 0.75 1.00 1.25 1. 50 1.75 2.00 2.25 2.50 2.75 3.00 0 10 20 30 40 50 60 70 80 90 100 output current (a) efficiency (%) v in =v cc =5.0v v out =1.0v AP3436 3.00 3.25 3.50 3.75 4.00 4.25 4.50 4.75 5.00 5.25 5.50 0.590 0.592 0.594 0.596 0.598 0.600 0.602 0.604 0.606 0.608 0.610 input voltage(v) reference voltage(v) v in =v cc =v en
data sheet 3a, 1.25mhz high performance synchronous buck converter AP3436/a jan. 2013 rev. 1.2 bcd semiconductor manufacturing limited 8 typical performance characteristics (continued) figure 8. pwm frequency vs. temperature figure 9. current limit vs. input voltage figure 10. current limit vs. temperature figure 11. line regulation vs. input voltage -40 -20 0 20 40 60 80 100 120 140 1.00 1.05 1.10 1.15 1.20 1.25 1.30 1.35 1.40 1.45 1.50 pwm frequency (mhz) temperature ( o c) v in =v cc =5.0v -40-20 0 20406080100120140 6.00 6.25 6.50 6.75 7.00 7.25 7.50 7.75 8.00 8.25 8.50 8.75 9.00 current limit (a) temperature ( o c) v in =v cc =5.0v 3.00 3.25 3.50 3.75 4.00 4.25 4.50 4.75 5.00 5.25 5.50 -0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 line regulation (%) input voltage (v) v out = 1.0v v in = v cc = v en 3.00 3.25 3.50 3.75 4.00 4. 25 4.50 4.75 5.00 5.25 5.50 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0 current limit (a) input voltage (v) v in =v cc =v en
data sheet 3a, 1.25mhz high performance synchronous buck converter AP3436/a jan. 2013 rev. 1.2 bcd semiconductor manufacturing limited 9 typical performance characteristics (continued) figure 12. load regulation vs. output current figure 13. power on waveform (v in =v cc =5v, v out =1v, i out =3a) figure 14. power off waveform figure 15. enable waveform (v in =v cc =5v, v out =1v, i out =3a) (v in =v cc =5v, v out =1v, i out =3a) v in 2v/div v out 500mv/div i l 1a/div time 400 s/div time 1ms/div i l 1a/div v out 500mv/div v cc/in 2v/div v en 1v/div 0.00 0.25 0.50 0.75 1.00 1.25 1. 50 1.75 2.00 2.25 2.50 2.75 3.00 -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 load regulation (%) output current (a) v in =v cc =v en =5.0v v out =1.0v time 20ms/div v in 2v/div i l 2a/div v out 1v/div
data sheet 3a, 1.25mhz high performance synchronous buck converter AP3436/a jan. 2013 rev. 1.2 bcd semiconductor manufacturing limited 10 typical performance characteristics (continued) figure 16. disable waveform figure 17. load transient response (v in =v cc =5v, v out =1v, i out =3a) (v in =v cc =5v, v out =1v, i out =0 to 3a) figure 18. load transient response (v in =v cc =3.3v, v out =1v, i out =0 to 3a) time 200 s/div v cc/in 2v/div v en 1v/div v out 500mv/div i l 1a/div v out_ac 20mv/div i out 1a/div time 200 s/div time 200 s/div v out_ac 20mv/div i out 1a/div
data sheet 3a, 1.25mhz high performance synchronous buck converter AP3436/a jan. 2013 rev. 1.2 bcd semiconductor manufacturing limited 11 typical application pgood ep en vcc fb gnd gnd sw sw boot vin r pg v cc c vcc v out c boot l1 c out r fb2 r fb1 v in c in 9 10 2 1 6 7 4 5 11 8 3 note 2: when using a single power supply for v cc and v in , a 4.7 ? resistor should be placed between them for noise isolation. figure 19. typical application circuit of AP3436/a table 1. component guide component value unit component value unit c vcc 1 f c in 44 f r pg 10 k ? c boot 0.1 f r fb2 tbd k ? l1 1.5 h r fb1 tbd k ? c out 88 f
data sheet 3a, 1.25mhz high performance synchronous buck converter AP3436/a jan. 2013 rev. 1.2 bcd semiconductor manufacturing limited 12 application information 1. overview the AP3436/a is a 3a synchronous buck (step-down) converter with two integrated n-channel mosfets. for AP3436, the regulator operates in pwm mode with 1.25mhz switching frequency internally, regardless of if the load current is high or low. for AP3436a, when the load is very light, the regulator automatically operates in the psm mode to minimize the switching loss, thus achi eving high efficiency at light load. when the load increases, the regulator automatically switches over to a current-mode pwm operating at nominal 1.25mhz switching frequency. 2. power on reset a power on reset (por) circuitry continuously monitors the supply voltage at vcc pin. once the rising por threshold is exceeded, the AP3436/a sets itself to active state and is ready to accept chip enable command. the rising por threshold is typically 2.75v . 3. soft start a built-in soft-start is used to prevent surge current from power supply input v in during turn on (referring to the functional block diagram). the error amplifier is a thr ee-input device. reference voltage v ref or the internal soft-start voltage v ss whichever is smaller dominates the behavior of the non-inverting inputs of the error amplifier. v ss internally ramps up to 0.6v after the soft-start cycle is initiated. the ramp is created digitally, so the output voltage will follow the v ss signal and ramps up smoothly to its target level. 4. en function the AP3436/a provides enable function. pulling this pin higher than 1.6v statically enables the AP3436/a while pulling the pin lower than 0.8v statically for longer than 10 s will shutdown the ic. 5. adjusting output voltage the output voltage is set with a resistor divider from the fb pin. it is recommended to use divider resistors with 1% tolerance or better. start with a 100k ? for the resistor r1 and use the following equation to calculate r2. consider using larger value resistors to improve efficiency at very light loads. if the values are too high, the regulator is more susceptible to noise and the voltage errors caused by fb input current are noticeable. figure 20. voltage divider circuit 6. short circuit protection (scp) the AP3436/a has over current protection (ocp) and under voltage protection (uvp) functions. 6.1 ocp function the high side switch current is detected during each cycle. during scp conditions, the output voltage is pulled down and the switch current is increased. once the increased high si de switching current is detected to trigger the current limit of high side switch, the high side switch will be immediately turned off and will not be turned on again until the next switching cycle. when over current condition is removed, the AP3436/a will recover back to normal operation again. 6.2 uvp function the fb voltage is also monitored for under voltage protection. the uv threshold is set at 0.2v. the under voltage protection has 65 s triggered delay. when uvp is triggered, both high side and low side are shutdown immediately. the uvp is a latched function, reset power supply or en pin to restart AP3436/a again. 7. over voltage protection (ovp) the output voltage is continuously monitored for over voltage protection by fb pin. when it is larger than 1.67 times as setting, the ovp function is triggered. the over voltage protection has 65 s triggered delay. when ovp is triggered, both high side and low side are shutdown immediately and the output voltage is discharged by an internal 1k ? resistor. 6 . 0 6 . 0 1 2 ? = out v r r fb v out r1 r2 AP3436/a - + + 0.6v v ss
data sheet 3a, 1.25mhz high performance synchronous buck converter AP3436/a jan. 2013 rev. 1.2 bcd semiconductor manufacturing limited 13 application information (continued) 8. power good the pgood pin output connects an open drain mosfet. the output is pulled low when the fb voltage enters the fault condition by falling below 75% or rising above 125% of the nominal internal reference voltage. there is a 7% hysteresis on the threshold voltage, so when the fb voltage rises to the good condition above 82% or falls below 118% of the internal voltage reference the pgood output mosfet is turned off. it is recommended to use a pull-up resistor between the values of 3k ? and 100k ? to a voltage source that is 5v or less. 9. thermal shutdown the device implements an in ternal thermal shutdown to protect itself if the j unction temperature exceeds 160c. switching is stopped when the junction temperature exceeds the thermal trip threshold. once the die temperature decr eases below 140c, the device reinitiates the soft start operation. the thermal shutdown hysteresis is 20c.
data sheet 3a, 1.25mhz high performance synchronous buck converter AP3436/a jan. 2013 rev. 1.2 bcd semiconductor manufacturing limited 14 mechanical dimensions dfn-33-10 unit: mm(inch) 2.900(0. 114) 3.100(0.122) 2.900(0. 114) 3.100(0. 122) 1.600(0. 063) 1.800(0. 071) 0.200(0. 008) 0.300(0. 012) 0.500(0. 020) typ 0.300(0. 012) 0.500(0. 020) 0.000(0. 000) 0.050(0. 002) 0.700(0.028) 0.800(0. 031) 0.153(0. 006) 0.253(0. 010) 2.300(0. 090) 2.500(0. 098) n1 n5 n6 n10 pin 1 mark pin #1 identification see detail a 1 2 detail a 1 2 1 2 pin 1 options
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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