AP5004 pwm control 2.5a step-down converter AP5004 rev. 3 1 of 10 june 2008 www.diodes.com ? diodes incorporated features general description AP5004 consists of step-down switching regulator with pwm control. these devices include a reference voltage source, oscillation circuit, error amplifier, internal nmos. ? input voltage: 10v to 32v ? adjustable output voltage from 0.8v to 6v ? duty ratio: 0% to 90% pwm control AP5004 provides low-ripple power, high efficiency and excellent transient characteristics. the pwm control circuit is able to vary the duty ratio linearly from 0 up to 90%. 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 300 khz to 50 khz. also, an internal compensation block is built to minimize external component count. ? oscillation frequency: 300khz typical ? short circuit protect frequency:50 khz ? 2ua maximum standby current ? current limit, enable function ? thermal shutdown function ? built-in internal sw n-channel mos ? sop-8l: available in ?green? molding compound (no br, sb) with built-in power nmos, a step-down switching regulator is easy to be built by adding a coil, capacitors and a diode. ? lead free finish/rohs compliant (note 1) the high efficiency, low standby current, high input voltage (32v) and output current (2.5a) combining with small sop-8l package give AP5004 unprecedented advantage in high power system applications. ? microprocessor core supply ? networking power supply ? lcd mnt, tv power supply ? telecom power supply ordering information AP5004 s g - x package packing u : tube 13 : tape & reel lead free g : green s : sop-8l tube 13? tape and reel device package code packaging (note 2) quantity part number suffix quantity part number suffix AP5004sg-u s sop-8l 100 -u na na AP5004sg-13 s sop-8l na na 2500/tape & reel -13 applications notes: 1. eu directive 2002/95/ec (rohs). all applicable rohs exemptions applied, see eu directive 2002/95/ec annex notes. 2. pad layout as shown on diodes inc. suggested d la yout document ap02001, which can be found on our website at pa http://www.diodes.com/d atasheets/ap02001.pdf .
AP5004 pwm control 2.5a step-down converter AP5004 rev. 3 2 of 10 june 2008 www.diodes.com ? diodes incorporated AP5004 1 2 3 7 6 5 4 8 (top view ) gnd gnd vcc vcc en fb vboost output sop-8l pin name pin # description en 1 h: normal operation l: step-down operation stopped fb 2 feedback pin v boost 3 high-side gate driver boost pin output 4 switch output pin v cc 5 6 signal v cc gnd 7 8 gnd pin block diagram oscillation circuit reference voltage pwm - switched control circuit + - gnd en output fb vboost vcc v en driver thermal shutdown vl pin assignments pin descriptions
AP5004 pwm control 2.5a step-down converter AP5004 rev. 3 3 of 10 june 2008 www.diodes.com ? diodes incorporated absolute maximum ratings symbol parameter rating unit esd hbm human body model esd protection 1.8 kv esd mm machine model esd protection 550 v v cc v cc pin voltage v ss - 0.3 to v ss + 35 v v fb v out pin voltage v ss - 0.3 to v cc v v en en pin voltage v ss - 0.3 to v cc + 0.3 v v boost v boost pin voltage v output + 7v v v output switch pin voltage v ss - 0.3 to v cc + 0.3 v t j operating junction temperature range -10 to +125 o c t st storage temperature range -40 to +150 o c caution: the absolute maximum ratings are rated values exceedi ng which the product could suffer physical damage. these values m ust therefore not be exceeded under any conditions. recommended operating conditions symbol parameter min max unit v in input voltage 10 32 v i out output current 0 2.5 a t a operating ambient temperature -10 85 o c
AP5004 pwm control 2.5a step-down converter AP5004 rev. 3 4 of 10 june 2008 www.diodes.com ? diodes incorporated electrical characteristics (v in = 12v, t a =25c, unless otherwise specified) symbol parameter conditions min typ. max unit v fb feedback voltage 0.780 0.8 0.820 v v in input voltage 10 - 32 v i stby standby current v en =0v - 2 - a ? v out /v out line regulation v in = 10v~32v - 1.0 1.5 %/v ? v out /v out load regulation i out = 0.1 to 2.5a - 1 1.5 % f osc oscillation frequency measure waveform at sw pin 240 300 360 khz f osc1 frequency of current limit or short circuit protect measure waveform at sw pin - 50 - khz maximum duty cycle v fb =0.5v - 90 - % dc minimum duty cycle v fb =1.0v - 0 - % v ih regulator on 2.0 - - v il en pin logic input threshold voltage regulator off - - 0.8 v i sh - 20 - a i sl en pin input leakage current - -10 - a r ds(on) internal mosfet r ds(on) - 80 120 m ? i limit current limit 3.5 - - a efficiency v in = 12v, v out = 5v, i out = 2.5a - 90 - % ja thermal resistance junction-to-ambient sop-8l (note 3) - 124 - o c/w jc thermal resistance junction-to-case sop-8l (note 3) - 25 - o c/w notes: 3. test condition for sop-8l: device mounte d on 2oz copper, minimum recommended pad layout, fr-4 pcb. typical application circuit vboost gnd vcc AP5004 gnd vcc output fb en 5 6 vin c3 0.1uf 1 c2 220uf/63v 8 3 4 2 7 d1 b340 r1 685ohm l1-(wurth 744132) 33uh c5 0.1uf c1 100pf vout = 5v r5 100k c6 0.1uf u1 c7 0.1uf 1 2 r2 130ohm c4 470uf/16v note : v out = v fb x (1+r1/r2) r b = 100 ~ 300 ohm notes: 4. suggested diodes power schottky p/n: pds540 or b540c.
AP5004 pwm control 2.5a step-down converter AP5004 rev. 3 5 of 10 june 2008 www.diodes.com ? diodes incorporated typical performance characteristics line regulation load regulation 0 0.2 0.4 0.6 0.8 1 1.2 0123 iout(a) load regulation(%) 0 0.3 0.6 0.9 1.2 1.5 0 4 8 121620242832 vin(v) line regulation(%) frequency vs. vin iccq vs. vin 310 315 320 325 330 0 5 10 15 20 25 30 35 vin(v) frequency(khz) vout=5v;iout=0.2a 7.05 7.1 7.15 7.2 7.25 7.3 7.35 7.4 7.45 0 5 10 15 20 25 30 35 vin(v) quiescent current(ma) vfb=1v istandby vs. vin 0 0.03 0.06 0.09 0.12 0.15 0 5 10 15 20 25 30 35 vin(v) standby current(ua) ven=0v
AP5004 pwm control 2.5a step-down converter AP5004 rev. 3 6 of 10 june 2008 www.diodes.com ? diodes incorporated typical performance characteristics (continued) vout ripple (vcc= 12v, vout= 5v, iout= 0a, vripple= 19.0mv) vout ripple (vcc= 12v, vout= 5v, iout= 2.5a, vripple= 35.0mv) power transient wave (iout= 0.1~2.5a, vi n= 12v, vout= 5v) power transient wave (iout= 0.1~2.5a, vin= 32v, vout= 5v)
AP5004 pwm control 2.5a step-down converter AP5004 rev. 3 7 of 10 june 2008 www.diodes.com ? diodes incorporated test circuit a fb vcc gnd en open open fb vcc gnd en + - oscillation output output a fb vcc gnd en + - + - v output vboost open vboost vboost enable function test feedback function test operation function test 220uf 0.1uf 33uh 470uf 530 ohm 100 ohm
AP5004 pwm control 2.5a step-down converter AP5004 rev. 3 8 of 10 june 2008 www.diodes.com ? diodes incorporated functional description pwm control the AP5004 consists of dc/dc converters that employ a pulse-width modulation (pwm) system. the pwm controller is internally clocked by a fixed 300khz oscillator. in converters of the AP5004, the pulse width varies in a range from 0 to 90%, 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. enable control this allows the output of AP5004 to be turned on or off. connecting this pin to gnd or any voltage lower than 0.8v turn off the output off. at off state current drawn through the v cc input is approximately 2ua. note that the slew rate from on to off must be >0.013v/us to ensure proper operation. c boost a capacitor must be connected from pin 3 to the switch output, pin 4. this capacitor boosts t he gate drive to the internal mosfet above v in to fully turn it on. this minimizes conduction losses in the power switch to maintain high efficiency. the recommended value for c boost is 0.1uf. feedback this is the input to a two-stage high gain amplifier, which drivers the pwm controller. it is necessary to connect pin 2 to the actual output of the power supply to set the dc output voltage. two external resistors are required to set the dc output voltage. for stable operation of the power supply, it is important to prevent coupling of any inductor flux to the feedback input. current limit the current limit threshold is se t by the internal circuit that minimum switching current is 3.5a. the output voltage will be reduced immediately and switching frequency will be dropped to 50khz when switching current over limit threshold. inductor selection for most designs, the operates with inductors of 15h to 33h. the inductor value can be derived from the following equation: () oscl on out in fi tvv l ? = where is inductor ripple curren t. large value inductors lower ripple current and small value i nductors result in high ripple currents. choose inductor ripple current approximately 15% of the maximum load current 2.5a, il=0.375a. the dc current rating of the inductor should be at least equal to the maximum load current plus half the ripple curr ent to prevent core saturation (2a+0.19a). input capacitor selection the input current to the step-do wn converter is discontinuous, and therefore an input capacitor c2 is required to supply the ac current to the step-down converter while maintaining the dc input voltage. a low esr capacitor is required to keep the noise at the ic to a minimum. its rms current rating should be greater than approximately 1/2 of the dc load current. output capacitor selection the output capacitor is required to maintain the dc output voltage. low esr capacitors are preferred to keep the output voltage ripple low. the characterist ics of the output capacitor also affect the stability of the regulation control system. the esr dominates the impedance at the switching frequency, and so the output ripple is calculated as: esr ripple riv ? output rectifier diode the output rectifier diode supplies the current to the inductor when the high-side switch is off. to reduce losses due to the diode forward voltage and recovery times, use a schottky rectifier. pcb layout guide if you need low t c & t j or large pd(power dissipation), the dual output pin(4) 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 ground side of the c2 & d1 as closely as possible. typical pc board layout top side layout guide bottom side layout guide
AP5004 pwm control 2.5a step-down converter AP5004 rev. 3 9 of 10 june 2008 www.diodes.com ? diodes incorporated marking information ( top view ) sop-8l AP5004 yy ww x x logo part no. internal code year : "07" = 2007 "08" = 2008 xth week : 01~52 ~ 5 8 4 1 a~z : green package information (all dimensions in mm) 1.27typ 0.3/0.5 7~9 4.80/5.30 3.70/4.10 5.79/6.20 0.20typ 7~9 3.70/4.10 0.38/1.27 0.08/0.25 gauge plane 0.254 seating plane 0.35max. 45 detail "a" detail "a" 1.30/1.50 1.75max. land pattern recommendation 0.78 (unit: mm) 6x-1.27 8x-1.55 8x-0.60 5.4
AP5004 pwm control 2.5a step-down converter AP5004 rev. 3 10 of 10 june 2008 www.diodes.com ? diodes incorporated 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 a ssume 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.
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