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AP65200 document number: ds35548 rev. 3 - 2 1 of 15 www.diodes.com december 2012 ? diodes incorporated new product a p65200 light load improved 2a syn ch dc/dc buck converter description the AP65200 is a 340khz switching frequency external compensated synchronous dc/dc buck converter. it has integrated low r dson high and low side mosfets. the AP65200 enables continues load current of up to 2a with efficiency as high as 95%. the AP65200 implements an automatic custom light load efficiency improvement algorithm. the AP65200 features current mode control operation, which enables fast transient response times and easy loop stabilization. the AP65200 simplifies board layout and reduces space requirements with its high level of integration and minimal need for external components, making it ideal for distributed power architectures. the AP65200 is available in a standard green so-8 package and is rohs compliant. features ? v in 4.75v to 18v ? 2a continuous output current, 3a peak ? efficiency up to 95% ? automated light load improvement ? v out adjustable to 0.925 to 16v ? 340khz switching frequency ? external programmable soft-start ? enable pin ? ocp and thermal protection ? totally lead-free & fully rohs compliant (notes 1 & 2) ? halogen and antimony free. ?green? device (note 3) pin assignments applications ? gaming consoles ? flat screen tv sets and monitors ? set top boxes ? distributed power systems ? home audio ? consumer electronics ? network systems ? fpga, dsp and asic supplies ? green electronics notes: 1. no purposely added lead. fully eu directiv e 2002/95/ec (rohs) & 2011/6 5/eu (rohs 2) compliant. 2. see http://www.diodes.com for more in formation about diodes incorpor ated?s definitions of halogen- and antimony-free, "gree n" and lead-free. 3. halogen- and antimony-free "green? products are defined as those which contain <900ppm br omine, <900ppm chlorine (<1500ppm t otal br + cl) and <1000ppm antimony compounds. typical applications circuit figure 1. typical application circuit http://www..net/ datasheet pdf - http://www..net/
AP65200 document number: ds35548 rev. 3 - 2 2 of 15 www.diodes.com december 2012 ? diodes incorporated new product a p65200 pin descriptions pin name pin number function so-8 bs 1 high-side gate drive boost input. bs supplies the drive for the high-side n-channel mosfet a 0.01f or greater capacitor from sw to bs to power the high side switch. in 2 power input. in supplies the power to the ic, as well as the step-down converter switc hes. drive in with a 4.75v to 18v power source. bypass in to gnd with a suitably large capacitor to eliminate noise on the input to the ic. see input capacitor. sw 3 power switching output. sw is the switching node that supplies power to the output. connect the output lc filter from sw to the output load. note that a capacitor is required from sw to bs to power the high-side switch. gnd 4 ground fb 5 feedback input. fb senses the output voltage and regulat es it. drive fb with a resistive voltage divider connected to it from the output voltage. the feedback th reshold is 0.925v. see setting the output voltage. comp 6 compensation node. comp is used to compensate the regulation control loop. connect a series rc network from comp to gnd. in some cases, an additional capacit or from comp to gnd is required. see compensation components. en 7 enable input. en is a digital input that turns the regulato r on or off. drive en high to turn on the regulator; low to turn it off. attach to in with a 100k ? pull up resistor for automatic startup. ss 8 soft-start control input. ss controls the soft-start period. connect a capacitor from ss to gnd to set the soft- start period. a 0.1f capacitor sets the soft-start peri od to 15ms. to disable the soft-start feature, leave ss floating. functional block diagram http://www..net/ datasheet pdf - http://www..net/
AP65200 document number: ds35548 rev. 3 - 2 3 of 15 www.diodes.com december 2012 ? diodes incorporated new product a p65200 absolute maximum ratings (note 4) (@t a = +25c, unless otherwise specified.) symbol parameter rating unit v in supply voltage -0.3 to +20 v v sw switch node voltage -1.0 to v in +0.3 v v bs bootstrap voltage v sw -0.3 to v sw +6.0 v v fb feedback voltage -0.3v to +6.0 v v en enable/uvlo voltage -0.3v to +6.0 v v comp comp voltage -0.3v to +6.0 v t st storage temperature -65 to +150 c t j junction temperature +160 c t l lead temperature +260 c esd susceptibility (note 5) hbm human body model 2 kv mm machine model 200 v notes: 4. stresses greater than the 'absolute maximum ratings' specified above may cause permanent damage to the device. these are stress ratings only; functional operation of the device at these or any other conditions exceeding those indicated in this specification is not implied. device reliability may be affected by exposure to absolute maximum rating conditions for extended periods of time. 5. semiconductor devices are esd sensitive and may be damaged by exposure to esd events. suitable esd precautions should be ta ken when handling and transporting these devices. thermal resistance (note 6) symbol parameter rating unit ja junction to ambient so-8 119 c/w jc junction to case so-8 31 c/w note: 6. test condition: so-8: device mounted on 1"x1" fr-4 substrate pcb, 2oz copper, with minimum recommended pad layout. recommended operating conditions (note 7) (@t a = +25c, unless otherwise specified.) symbol parameter min max unit v in supply voltage 4.75 18.0 v t a operating ambient temperature range -40 +85 c note: 7. the device function is not guaranteed outside of the recommended operating conditions. http://www..net/ datasheet pdf - http://www..net/
AP65200 document number: ds35548 rev. 3 - 2 4 of 15 www.diodes.com december 2012 ? diodes incorporated new product a p65200 electrical characteristics (@t a = +25c, v in = 12v, unless otherwise specified.) symbol parameter test conditions min typ max unit i in shutdown supply current v en = 0v 0.3 3.0 a i in supply current (quiescent) v en = 2.0v, v fb = 1.0v 0.6 1.5 ma r ds(on)1 high-side switch on-resistance (note 8) 130 m ? r ds(on)2 low-side switch on-resistance (note 8) 130 m ? i limit hs current limit minimum duty cycle 4.4 a i limit ls current limit from drain to source 0.9 a high-side switch leakage current v en = 0v, v sw = 0v, v sw =12v 0 10 a avea error amplifier voltage gain (note 8) 800 v/v gea error amplifier transconductance i c = 10a 1000 a/v gcs comp to current sense transconductance 2.8 a/v f sw oscillator frequency v fb = 0.75v 300 340 380 khz f fb fold-back frequency v fb = 0v 0.30 f sw d max maximum duty cycle v fb = 800mv 90 % t on minimum on time 130 ns v fb feedback voltage t a = -40c to +85c 900 925 950 mv feedback overvoltage threshold 1.1 v v en_rising en rising threshold 0.7 0.8 1.2 v en lockout threshold voltage 2.2 2.5 2.7 v en lockout hysteresis 220 mv inuv vth v in under voltage threshold rising 3.80 4.05 4.40 v inuv hys v in under voltage threshold hysteresis 250 mv soft-start current v ss = 0v 6 a soft-start period c ss = 0.1f 15 ms t sd thermal shutdown (note 8) 160 c note: 8. guaranteed by design. http://www..net/ datasheet pdf - http://www..net/
AP65200 document number: ds35548 rev. 3 - 2 5 of 15 www.diodes.com december 2012 ? diodes incorporated new product a p65200 typical performance characteristics (@t a = +25c, v in = 12v, v out = 3.3v, unless otherwise specified.) http://www..net/ datasheet pdf - http://www..net/
AP65200 document number: ds35548 rev. 3 - 2 6 of 15 www.diodes.com december 2012 ? diodes incorporated new product a p65200 typical performance characteristics (cont.) (@t a = +25c, v in = 12v, v out = 3.3v, unless otherwise specified.) http://www..net/ datasheet pdf - http://www..net/
AP65200 document number: ds35548 rev. 3 - 2 7 of 15 www.diodes.com december 2012 ? diodes incorporated new product a p65200 typical performance characteristics (cont.) (@t a = +25c, v in = 12v, v out = 3.3v, l = 3.3h, c1 = 22f, c2 = 47f, unless otherwise specified.) steady state test 2a time-2s/div startup through vin no load time-5ms/div startup through vin 2a load time-5ms/div load transient test 0.15 to 2a time-500s/div shutdown through vin no load time-20ms/div shutdown through vin 2a time-100s/div short circuit test time-20s/div short circuit recovery time-50s/div load transient test 0.15 to 2a time-20s/div load transient test 2a to 0.15a time-20s/div http://www..net/ datasheet pdf - http://www..net/
AP65200 document number: ds35548 rev. 3 - 2 8 of 15 www.diodes.com december 2012 ? diodes incorporated new product a p65200 application information theory of operation the AP65200 is a 2a current mode control, synchronous buck regulator with built in power mosfets. current mode control assures excellent line and load regulation and a wide loop bandwidth for fast respons e to load transients. the figure 1 depicts the functional bl ock diagram of AP65200. the operation of one switching cycle can be explained as follows. at the beginning of each cycle, hs (high-side) mosfet is off. the error amplifier (ea) output voltage is higher than the current sense amplifier output, and the current comparator?s output is low. the rising edge of the 340khz oscillator clock signal sets the rs flip-flop. its output turns on hs mosfet. the current sense amplifier is reset for e very switching cycle. when the hs mosfet is on, inductor current starts to increase. the current sense am plifier senses and amplifies the inductor cu rrent. since the current mode control is subject to sub-harmonic oscillations that peak at half the switching frequency, ramp slope compensa tion is utilized. this will help to stabilize the power supply. this ramp compens ation is summed to the current sense amplifier output and compar ed to the error amplifier output by the pwm comparator. when the sum of the cu rrent sense amplifier output and the slope compensation signal ex ceeds the ea output voltage, the rs flip-flop is reset and hs mosfet is turned off. for one whole cycle, if the sum of the current sense amplif ier output and the slope compensation signal does not exceed the ea output, then the falling edge of the oscillator clock resets the flip-flop. the output of the error amplifier increases when feedback voltage (v fb) is lower than the reference voltage of 0.925v. this also increases the i nductor current as it is proportional to the ea voltage. if in one cycle the current in the power mosfet does not reach th e comp set current value, the power mosfet will be forced to turn off. when the hs mosfet turns off, the synchronous ls mosfet turns on unt il the next clock cycle begins. there is a ?dead time? between the hs turn off and ls turn on that prevents the switches from ?shooting through? from the input supply to ground. the voltage loop is compensated through an internal transconduct ance amplifier and can be adjusted through the external compens ation components. enable above the ?en rising threshold?, the inter nal regulator is turned on and the quiescent current can be measured above this thres hold. the enable (en) input allows the user to control turning on or off the regulator. to enable the AP65200, en must be pulled above the ?en l ockout threshold voltage? and to disable the AP65200, en must be pulled below ?en lockout threshold voltage - en lockout hysteresis? (2.2v - 0.22v = 1.98v). automated no-load and light-load operation the AP65200 operates in light load high e fficiency mode during light load operation. the advantage of this light load high effi ciency mode is low power loss at no-load and light-load conditions. the AP65200 automatically detects the output current and enters th e light load high efficiency m ode. the output current reaches a critical level at which the transitions between the light-load and heavy current m ode occurs. once the output current exceeds the critical lev el, the AP65200 transitions from light load high efficiency mode to continuous pwm mode. external soft start soft start is traditionally implemented to prevent the excess inru sh current. this in turn prevents the converter output voltage from overshooting when it reaches regulation. the AP65200 has an internal current s ource with a soft start capacitor to ramp the reference voltag e from 0v to 0.925v. the soft start current is 6a. the soft start sequence is reset when there is a thermal shutdown, under voltage lockout (uvlo) or when the part is disabled using the en pin. http://www..net/ datasheet pdf - http://www..net/
AP65200 document number: ds35548 rev. 3 - 2 9 of 15 www.diodes.com december 2012 ? diodes incorporated new product a p65200 application information (cont.) external soft start (cont.) external soft start can be calculated from the formula below: dt dv *c ss i = where; i ss = soft start current c = external capacitor dv=change in feedback voltage from 0v to maximum voltage dt = soft start time current limit protection in order to reduce the total power dissipation and to protect the application, AP65200 has cycle-by-cycle current limiting impl ementation. the voltage drop across the internal high-side mosf et is sensed and compared with the internally set current limit threshold. this voltage drop is sensed at about 30ns after the hs turns on. when the peak inductor current exceeds the set current limit threshold, current lim it protection is activated. during this time the feedback voltage (vfb) drops down . when the voltage at the fb pin reaches 0.3v, the internal o scillator shifts the frequency from the normal operating frequency of 340khz to a fold-back frequency of 102khz. the current limit is reduced to 70% of nominal current limit when the part is operating at 102khz. this low fold-back frequency prevents runaway current. under voltage lockout (uvlo) under voltage lockout is implemented to prevent the ic from in sufficient input voltages. the AP65200 has a uvlo comparator that monitors the input voltage and the internal bandgap reference. if the input voltage falls below 4.0v, the AP65200 will latch an under vo ltage fault. in this event the output will be pulled low and power has to be re-cycled to reset the uvlo fault. over voltage protection when the AP65200 fb pin exceeds 20% of the nominal regulation voltage of 0.925v, the over voltage comparator is tripped and the comp pin and the ss pin are discharged to gnd, forcing the high-side switch off. thermal shutdown the AP65200 has on-chip thermal protection that prevents damage to the ic when the die temperature exceeds safe margins. it imp lements a thermal sensing to monitor the operating j unction temperature of the ic. once the die temperature rises to approximately +160c , the thermal protection feature gets activated. the inter nal thermal sense circuitry turns the ic of f thus preventing the power switch from damage. a hysteresis in the thermal sense circui t allows the device to cool down to approx imately +120c before the ic is enabled again through soft start. this thermal hysteresis feature prevents undesir able oscillations of the t hermal protection circuit. setting the output voltage the output voltage can be adjusted from 0.925v to 16v using an external resistor divider. table 1 shows a list of resistor selection for common output voltages. resistor r1 is selected based on a design tr adeoff between efficiency and output voltage accuracy. for high va lues of r1 there is less current consumption in the feedback network. however the tr ade off is output voltage accuracy due to the bias current i n the error amplifier. r1 can be determined by the following equation: ? ? ? ? ? ? ? ? ??= 1 0.925 out v 2 r 1 r figure 2. feedback divider network table 1. resistor selection for common output voltages v out (v) r1 (k ? ) r2 (k ? ) 5 44.2 10 3.3 26.1 10 2.5 16.9 10 1.8 9.53 10 1.2 3 10 http://www..net/ datasheet pdf - http://www..net/
AP65200 document number: ds35548 rev. 3 - 2 10 of 15 www.diodes.com december 2012 ? diodes incorporated new product a p65200 application information (cont.) compensation components the AP65200 has an external comp pin through which system stabilit y and transient response can be c ontrolled. comp pin is the o utput of the internal trans-conductance error amplifier. a series capacitor-resistor combination sets a pole-zero combination to control the characteristics of the control system. the dc gain of the voltage feedback loop is given by: out fb vea cs load vdc v v agra = where v fb is the feedback voltage (0.925v), r load is the load resistor value, g cs is the current sense trans-conductance and a vea is the error amplifier voltage gain. the control loop trans fer function incorporates two poles one is due to the compensation capacitor (c3) and the output resistor of error amplifier, and the other is due to the output capacitor and the load resistor . these poles are located at: vea ea p1 a3c2 g f = load p2 r2c2 1 f = where g ea is the error amplifier trans-conductance. one zero is present due to the compensation capacitor (c3) an d the compensation resistor (r3). this zero is located at: 3r3c2 1 f z1 = the goal of compensation design is to shape the converter transfer function to get a desired loop gain. the system crossover fr equency where the feedback loop has the unity gain is crucial. a rule of thumb is to set the crossover frequency to below one -tenth of the switching frequency. use the following procedure to optimize the compensation components: 1. choose the compensation resistor (r3) to set the desired cr ossover frequency. determine the r3 value by the following equati on: fb out cs g ea fb out csea v v g fs1.02c2 v v gg fc2c2 3r < = where f c is the crossover frequency, which is typically less than one tenth of the switching frequency. 2. choose the compensation capacitor (c3) to achieve the desired phas e margin set the compensation zero, f z1 , to below one fourth of the crossover frequency to provide suffi cient phase margin. determine the c3 value by the following equation: fc3r 2 3c > where r3 is the compensation resistor value. v out (v) c in /c1 (f) c out /c2 (f) r c /r3 (k ? ) c c /c3 (nf) l1 (h) 1.2 22 47 3.24 6.8 3.3 1.8 22 47 6.8 6.8 3.3 2.5 22 47 6.8 6.8 10 3.3 22 47 6.8 6.8 10 5 22 47 6.8 6.8 10 12 22 47 6.8 6.8 15 table 2. recommended component selection inductor calculating the inductor value is a critic al factor in designing a buck converter. for most designs, the following equation can be used to calculate the inductor value; swlin out in out f ? iv )v(vv l ?? ?? = where l ?i is the inductor ripple current. and sw f is the buck converter switching frequency. http://www..net/ datasheet pdf - http://www..net/
AP65200 document number: ds35548 rev. 3 - 2 11 of 15 www.diodes.com december 2012 ? diodes incorporated new product a p65200 application information (cont.) inductor (cont.) choose the inductor ripple current to be 30 % of the maximum load current. the maximum inductor peak current is calculated from: 2 i ii l load l(max) += peak current determines the required saturati on current rating, which influences the si ze of the inductor. saturating the induc tor decreases the converter efficiency while increas ing the temperatures of the inductor and the in ternal mosfets. hence choosing an inductor wit h appropriate saturation current rating is important. a 1h to 10h inductor with a dc current rati ng of at least 25% percent higher than the maximum load current is recommended for most applications. for highest efficiency, the inductor ?s dc resistance should be less than 200m ? . use a larger inductance for im proved efficiency under light load conditions. input capacitor the input capacitor reduces the surge curr ent drawn from the input supply and the swit ching noise from the device. the input ca pacitor has to sustain the ripple current produced during the on time on the upper mosfet. it mu st hence have a low esr to minimize the losses . the rms current rating of the input capacitor is a critical parameter that must be hi gher than the rms input current. as a rule of thumb, select an input capacitor which has rms rating that is greater than half of the maximum load current. due to large di/dt through the input capacitors, electrolytic or ceramics should be used. if a tant alum must be used, it must b e surge protected. otherwise, capacitor failure could occur. for most applications, a 4.7f cerami c capacitor is sufficient. output capacitor the output capacitor keeps the output voltage ripple small, ensures feedback loop stability and reduces the overshoot of the output voltage. the output capacitor is a basic component for t he fast response of the power supply. in fact, during load trans ient, for the first few microseconds it supplies the current to the load. the converter recognizes the l oad transient and sets the duty cycle to maximum, but the curre nt slope is limited by the inductor value. maximum capacitance required can be calc ulated from the following equation: esr of the output capacitor dominates t he output voltage ripple. the amount of rippl e can be calculated from the equation below : esr* i vout inductor capacitor = an output capacitor with ample capacitance and low esr is the bes t option. for most applications , a 22f ceramic capacitor will be sufficient. 2 out 2 out 2 inductor out o v)v v( ) 2 i l(i c ?+ + = where v is the maximum output voltage overshoot. http://www..net/ datasheet pdf - http://www..net/
AP65200 document number: ds35548 rev. 3 - 2 12 of 15 www.diodes.com december 2012 ? diodes incorporated new product a p65200 application information (cont.) pc board layout this is a high switching frequency converter. hence attention must be paid to the swit ching currents interference in the layout . switching current from one power device to another can gener ate voltage transients across the impedances of the interconnecting bond wires and ci rcuit traces. these interconnecting impedanc es should be minimized by using wide, short printed circuit traces. external bootstrap diode it is recommended that an external bootstrap diode be added when the input voltage is no greater than 5v or the 5v rail is avai lable in the system. this helps to improve the efficienc y of the regulator. this solution is also applicable for d > 65%. the bootstrap diod e can be a low cost one such as bat54 or a schottky that has a low v f . figure 7?external bootstrap compensation components recommended diodes: part number voltage/current rating vendor b130 30v, 1a diodes inc sk13 30v, 1a diodes inc http://www..net/ datasheet pdf - http://www..net/
AP65200 document number: ds35548 rev. 3 - 2 13 of 15 www.diodes.com december 2012 ? diodes incorporated new product a p65200 ordering information part number package code tape and reel quantity part number suffix AP65200s-13 s 2500 -13 marking information (1) so-8 http://www..net/ datasheet pdf - http://www..net/
AP65200 document number: ds35548 rev. 3 - 2 14 of 15 www.diodes.com december 2012 ? diodes incorporated new product a p65200 package outline dimensions (all dimensions in mm.) please see ap02002 at http://ww w.diodes.com/datasheets/ap02002. pdf for latest version. (1) so-8 suggested pad layout please see ap02001 at http://www. diodes.com/datasheets/ap02001.pdf for the latest version. (1) so-8 so-8 dim min max a - 1.75 a1 0.10 0.20 a2 1.30 1.50 a3 0.15 0.25 b 0.3 0.5 d 4.85 4.95 e 5.90 6.10 e1 3.85 3.95 e 1.27 typ h - 0.35 l 0.62 0.82 0 8 all dimensions in mm dimensions value (in mm) x 0.60 y 1.55 c1 5.4 c2 1.27 gauge plane seating plane detail ?a? detail ?a? e e1 h l d e b a2 a1 a 45 7 ~ 9 a3 0.254 x c1 c2 y http://www..net/ datasheet pdf - http://www..net/
AP65200 document number: ds35548 rev. 3 - 2 15 of 15 www.diodes.com december 2012 ? diodes incorporated new product a p65200 important notice diodes incorporated makes no warranty of any kind, express or implied, with regards to this document, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose (and their equivalents under the laws of any jurisdiction). diodes incorporated and its subsidiaries rese rve the right to make modi fications, enhancements, improv ements, corrections or ot her changes without further notice to this document and any product descri bed herein. diodes incorporated does not assume any liability ari sing out of the application or use of this document or any product described her ein; neither does diodes incor porated convey any license under its patent or trademark rights, nor the rights of others. any customer or us er of this document or products described herein in such applica tions shall assume all risks of such use and will agree to hold diodes incorporated and all the companies whose products are represented on diodes incorporated website, harmless against all damages. diodes incorporated does not warrant or accept any liability whatsoever in respect of any products purchased through unauthoriz ed sales channel. should customers purchase or use diodes inco rporated products for any unintended or una uthorized application, customers shall i ndemnify and hold diodes incorporated and its representativ es harmless against all claims, damages, expenses, and attorney fees arising out of, directly or indirectly, any claim of personal injury or death a ssociated with such unintended or unauthorized application. products described herein may be covered by one or more united states, international or fore ign patents pending. product names and markings noted herein may also be covered by one or more un ited states, international or foreign trademarks. this document is written in english but may be translated into multiple languages for reference. only the english version of t his document is the final and determinative format released by diodes incorporated. life support diodes incorporated products are specifically not authorized for use as critical component s in life support devices or systems without the express written approval of the chief executive offi cer of diodes incorporated. as used herein: a. life support devices or systems are devices or systems which: 1. are intended to implant into the body, or 2. support or sustain life and whose failure to perform when proper ly used in accordance with in structions for use provided in the labeling can be reasonably expected to result in significant injury to the user. b. a critical component is any component in a life support devic e or system whose failure to perform can be reasonably expected to cause the failure of the life support device or to affect its safety or effectiveness. customers represent that they have all necessary expertise in the safety and regulatory ramifi cations of their life support dev ices or systems, and acknowledge and agree that they are solely responsible for all legal, regulatory and safety-rel ated requirements concerning the ir products and any use of diodes incorporated products in su ch safety-critical, life support devices or systems, notwithstanding any devices- or s ystems-related information or support that may be provided by diodes incorporated. further, customer s must fully indemnify diodes incorporate d and its representatives against any damages arisi ng out of the use of diodes incorporated pr oducts in such safety-critical, life suppor t devices or systems. copyright ? 2012, diodes incorporated www.diodes.com http://www..net/ datasheet pdf - http://www..net/

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