ap5002 pwm control 2a step-down converter ap5002 rev. 8 1 of 10 february 2009 www.diodes.com ? diodes incorporated ? input voltage: 3.6v to 20v ? output voltage: 0.8v to v cc ? duty ratio: up to 100% pwm control ? oscillation frequency: 500khz typical ? soft-start current limit, enable function ? thermal shutdown function ? built-in internal sw p-channel mos ? low esr output capacitor (mlcc, multi-layer ceramic capacitor) support ? efficiency 90% ? sop-8l: available in ?green? molding compound (no br, sb) ? lead free finish / rohs compliant (note 1) ap5002 consists of step-down switching regulator with pwm control. these devices include a reference voltage source, oscillation circuit, error amplifier, internal pmos. ap5002 provides low-ripple power, high efficiency, and excellent transient characteristics. the pwm control circuit is able to vary the duty ratio linearly up to 100%. this converter also contains an error amplifier circuit as well as a soft-start circuit that prevents overshoot at startup. an enable function, an over current protect function and a short circuit protect function are built inside, and when ocp or scp happens, the operation frequency will be reduced from 500khz to 50khz. also, an internal compensation block is built in to minimum external component count. with the addition of an internal p-channel power mos, a coil, capacitors, and a diode connected externally, these ics can function as step-down switching regulators. they serve as ideal power supply units for portable devices when coupled with the sop?8l mini-package, providing such outstanding features as low current consumption. since this converter can accommodate an input voltage up to 22v, it is also suitable for the operation via an ac adapter. ? pc motherboard ? lcd monitor ? graphic card ? dvd-video player ? telecom equipment ? adsl modem ? printer and other peripheral equipment ? microprocessor core supply ? networking power supply ap5002 s g - 13 package packing s : sop-8l 13 : tape & reel green g : green device package code packaging (note 2) 13? tape and reel quantity part number suffix ap5002sg-13 s sop-8l 2500/tape & reel -13 notes: 1. eu directive 2002/95/ec (rohs). all applicable rohs exemptions applied. please visit our website at http://www.diodes.com/products/lead_free.html . 2. pad layout as shown on diodes inc. suggested pad layout document ap02001, which can be found on our website at http://www.diodes.com/datasheets/ap02001.pdf . features general description applications ordering information
ap5002 pwm control 2a step-down converter ap5002 rev. 8 2 of 10 february 2009 www.diodes.com ? diodes incorporated ( top view ) 1 2 3 4 8 7 6 5 fb output comp sop-8l ap5002 output en vss vss v cc name pin description fb 1 feedback pin en 2 power-off pin h: normal operation (step-down operation) l: step-down operation stopped ( all circuits deactivated ) comp 3 compensation pin v cc 4 ic power supply pin output 5 6 switch pin. connect external inductor/diode here. minimize trace area at this pin to reduce emi. v ss 7 8 gnd pin block diagram oscillation circuit reference voltage source pwm-switched control circuit + - vss v en en 100ua comp fb vcc thermal shutdown output pin assignments pin descriptions
ap5002 pwm control 2a step-down converter ap5002 rev. 8 3 of 10 february 2009 www.diodes.com ? diodes incorporated absolute maxi mum ratings symbol parameter rating unit esd hbm human body model esd protection 5 kv esd mm machine model esd protection 200 v v cc v cc pin voltage v ss - 0.3 to v ss + 22 v v fb feedback pin voltage v ss - 0.3 to v cc v v en en pin voltage v ss - 0.3 to v in v v output switch pin volta g e v ss - 0.3 to v in v p d power dissipation 1000 mw t j operating junction temperature range -20 to +125 o c t st storage temperature range -65 to +150 o c caution: the absolute maximum ratings are rated values exceeding which the product could suffer physical damage. these values m ust therefore not be exceeded under any conditions. recommended oper ating conditions symbol parameter min max unit v in input voltage 3.6 20 v i out output current 0 2 a t a operating ambient temperature -20 85 o c
ap5002 pwm control 2a step-down converter ap5002 rev. 8 4 of 10 february 2009 www.diodes.com ? diodes incorporated electrical characteristics (v in = 12v, t a = 25 c, unless otherwise specified) symbol parameter conditions min typ. max unit v fb feedback voltage i out = 0.1a 0.784 0.8 0.816 v i fb feedback bias current i out = 0.1a - 0.1 0.5 a i ccq quiescent current v fb = 1.2 force drive off - 3 5 ma i sw switch current -- 3.5 - - a i sd shutdown supply current v en = 0v - 10 - a ? v out /v out line regulation v in = 4v~20v, i out = 0.2a - 1 2 % ? v out /v out load regulation i out = 0.1 to 2a - 0.5 1 % f osc oscillation frequency measure wavefo rm at sw pin 400 500 600 khz v sh en pin input voltage evaluate oscillation at sw pin 2.0 - - v v sl evaluate oscillation stop at sw pin - - 0.8 i sh en pin input leakage current ven = 2v -10 - 10 a i sl ven = 0.8v -10 - 10 a t ss soft-start time -- - 3 - ms r dson internal mosfet rdson v in = 5v, v fb = 0v - 110 150 m ? v in = 12v, v fb = 0v - 70 100 thermal shutdown 140 o c minimum duty cycle 6.5 % ja thermal resistance junction-to-ambient sop-8l (note 3) 124 o c/w jc t hermal resistance junction-to-case sop-8l (note 3) 25 o c/w notes: 3. test condition: device mounted on 2oz copper, minimum recommended pad layout, fr-4 pcb.
ap5002 pwm control 2a step-down converter ap5002 rev. 8 5 of 10 february 2009 www.diodes.com ? diodes incorporated typical application circuit u1 ap5002 1 2 3 4 5 6 7 8 fb en comp vcc output output vss vss c8 0.1uf c3 0.1uf c6 0.1uf c7 0.1uf c1 330pf c4 22uf d1 dii 723 b340a l1-(wurth s05100104) 10uh 1 2 r4 0.8~2k r1 3.8k vin+12v r2 1.2k r5 100k vout = 3.3v c2 22uf on/off compensation capacitor selection(mlcc) vin vout r4 c7 c1 12v 5/ 3.3/ 2.5/ 1.8/ 1.5v 0.8~2k 0.1f 330pf 5v 3.3/ 2.5/ 1.8/ 1.5v 0.8~2k 27nf 330pf vout = 3.3v 10uh 1 2 r1 3.8k on/off u1 ap5002 1 2 3 4 5 6 7 8 fb en comp vcc output output vss vss r4 4.7~6.8k c3 0.1uf c8 0.1uf c6 0.1uf c7 33nf c1 330pf c4 470uf d1 b340a vin+12v r2 1.2k r5 100k c2 470uf dii 723 l1-(wurth s05100104) notes: 4. v out = v fb ) r2 r1 (1 +
ap5002 pwm control 2a step-down converter ap5002 rev. 8 6 of 10 february 2009 www.diodes.com ? diodes incorporated typical performance characteristics ap5002 vin vs. frequency (vout=3.3v; iout=0.2a) 510 520 530 540 550 560 570 0 5 10 15 20 25 vin(v) frequency(khz) ap5002 temperature vs. frequency (vout=3.3v; iout=0.2a) 485 500 515 530 545 560 575 -20 0 20 40 60 80 100 120 frequency(khz) temperature( ) ap5002 vin vs. fb (vout=3.3v; iout=0.2a) 0.8 0.802 0.804 0.806 0.808 0 5 10 15 20 25 vin(v) vfb(v) ap5002 temperature vs. fb (vout=3.3v; iout=0.2a) 0.78 0.79 0.8 0.81 0.82 - 2 03 08 01 3 0 vfb(v) temperature( ) ap5002 efficiency 0 10 20 30 40 50 60 70 80 90 100 0 0.5 1 1.5 2 iout( a ) efficiency(%) vout=5v vout=3.3v
ap5002 pwm control 2a step-down converter ap5002 rev. 8 7 of 10 february 2009 www.diodes.com ? diodes incorporated typical performance ch aracteristics (continued) ap5002 load regulation 3.3 3.31 3.32 3.33 3.34 3.35 00.511.52 iout( a ) vout(v) ap5002 line regulation 3.3 3.31 3.32 3.33 3.34 3.35 0 5 10 15 20 25 vin(v) vout(v) ap5002 vin vs. i ccq (vout=3.3v) 0 1 2 3 4 5 0 5 10 15 20 vin(v) i ccq (ma) ap5002 temperature vs. i ccq (vout=3.3v) 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 -20 0 20 40 60 80 100 120 i ccq (ma) temperature( )
ap5002 pwm control 2a step-down converter ap5002 rev. 8 8 of 10 february 2009 www.diodes.com ? diodes incorporated typical performance characteristics (continued) ap5002 v out ripple (vin=12v; vout=5v; iout=0.2a) a p5002 v out ripple (vin=12v; vout=5v; iout=2a) test circuit a fb vcc vss en open open fb vcc vss en + - oscillation output output a fb vcc vss en + - + - v output comp comp comp enable function test feedback function test operation function test 1.2k 6.8k 22u 6.8k 1500p
ap5002 pwm control 2a step-down converter ap5002 rev. 8 9 of 10 february 2009 www.diodes.com ? diodes incorporated functional description pwm control the ap5002 consists of dc/dc converters that employ a pulse-width modulation (pwm) system. in converters of the ap5002, the pulse width varies in a range up to 100%, according to the load current. the ripple voltage produced by the switching can easily be removed through a filter because the switching frequency remains constant. therefore, these converters provide a low-ripple power over broad ranges of input voltage and load current. r ds(on) current limiting the current limit threshold is set by the internal circuit. setting the output voltage application circuit item shows the basic application circuit with adjustable output version. the external resistor sets the output voltage according to the following equation: v out (v) r1 (k ? ) r2 (k ? ) 5 6.4 1.2 3.3 3.8 1.2 2.5 2.6 1.2 1.8 3.3 2.6 1.5 3.3 3.7 1.2 3.3 6.5 1 3.3 13 inductor selection for most designs, the operates with inductors of 10h to 22h. the inductor value can be derived from the following equation: oscl on out in fi2 tvv l u ' u where is inductor ripple current. large value inductors lower ripple current and small value inductors result in high ripple currents. choose inductor ripple current approximately 15% of the maximum load current 2a, il=0.3a. the dc current rating of the inductor should be at least equal to the maximum load current plus half the ripple current to prevent core saturation (2a+0.15a). input capacitor selection el cap this capacitor should be located close to the ic using short leads and the voltage rating should be approximately 1.5 times the maximum input voltage. the rms current rating requirement for the input capacitor of a buck regulator is approximately 1 2 the dc load current. a low esr input capacitor sized for maximum rms current must be used. a 470f low esr capacitor for most applications is sufficient. mlcc cap a 22f mlcc capacitor for most applications is sufficient. output capacitor selection el cap the output capacitor is required to filter the output voltage and provides regulator loop stability. the important capacitor parameters are the 100khz equivalent series resistance (esr), the rms ripples current rating, voltage rating and capacitance value. for the output capacitor, the esr value is the most important parameter. the output ripple can be calculated from the following formula. es r iv l ripple u ' the bulk capacitor?s esr will determine the output ripple voltage and the initial voltage drop after a high slew-rate transient. an aluminum electrolytic capacitor's esr value is related to the capacitance and its voltage rating. in most case, higher voltage electrolytic capacitors have lower esr values. most of the time, capacitors with much higher voltage ratings may be needed to provide the low esr values required for low output ripple voltage. mlcc cap a 22f mlcc capacitor for most applications is sufficient. pcb layout guide if you need low t c & t j or large pd(power dissipation), the dual sw pins(5& 6) and vss pins(7& 8)on the sop-8l package are internally connected to die pad, the pcb layout should allow for maximum possible copper area at the sw pins. 1. connect c3 to vcc and vss pin as closely as possible to get good power filter effect. 2. connect r4 to vcc and ocset pin as closely as possible. 3. connect ground side of the c2 & d1 as closely as possible. typical pc board layout top side layout guide bottom side layout guide use vias to conduct the heat into the backside of pcb layer. the pcb heat sink copper area should be solder-painted without masked. this approaches a ?best case? pad heat sink.
ap5002 pwm control 2a step-down converter ap5002 rev. 8 10 of 10 february 2009 www.diodes.com ? diodes incorporated marking information ( top view ) ap5002 yy ww x x logo part number 5 8 4 1 ww : week : 01~52; 52 yy : year : 08, 09,10~ g : green x : internal code represents 52 and 53 week package information (all dimensions in mm) 1.27typ 0.3/0.5 7~9 4.85/4.95 3.85/3.95 5.90/6.10 0.15/0.25 7~9 0.62/0.82 0.10/0.20 gauge plane 0.254 seating plane 0.35max. 45 detail "a" detail "a" 1.30/1.50 1.75max. land pattern recommendation (unit: mm) 6x-1.27 8x-1.55 8x-0.60 5.4 0/8 important notice life support diodes incorporated and its subsidiaries reserve the right to make modifications, enhancements, improvements, corrections or ot her changes without further notice to any product herein. diodes incorporated does not assume any liability arising out of the application or use of any pr oduct described herein; neither does it convey any license under its patent rights, nor the rights of others. the user of products in such applications shall assume all risks of such use and will agree to hold diodes incorporated and all the companies whose products are represented on our website, harmless against all dam ages. diodes incorporated products are not authorized for use as critical components in life support devices or systems without the e xpressed written approval of the president of diodes incorporated.
|
