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ap65211a document number: ds39744 rev. 1 - 2 1 of 13 www.diodes.com june 2017 ? diodes incorporated ap65211a new product tsot26 light load improved 2a synch dc-dc buck converter description the ap65211a is a 500 khz switching frequency internal compensated synchronous dc-dc buck converter. it ha s integrated low r ds ( on ) high and low side mosfets. the ap65211a enables continuous load current of up to 2a with efficiency as high as 97 %. the ap65211a implements an automatic custom light load efficien cy improvement algorithm. the ap65211a features current mode control operation, whic h enables fast transient response time and easy loop stabili zation. the ap65211a 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 ap65211a is available in a standard green tsot26 package and is rohs compliant. features ? v in 4 .5 v to 18v ? 2a continuous output current ? efficiency up to 97% ? automated light load improvement ? v out adjustable from 0.8v ? 500khz switching frequency ? internal soft-start ? enable pin ? overvoltage protection & undervoltage protection ? overcurrent protection (o cp ) with hiccup ? thermal protection ? totally lead-free & fully rohs compliant (notes 1 & 2) ? halogen and antimony free. green device (note 3) pin assignments (top view) 3 2 1 6 4 5 gnd sw in bst en fb tsot26 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 directive 2002/95/ec (rohs ) & 2011/65/eu (rohs 2) compliant. 2. see http://www.diodes.com/quality/lead_free.html for more information ab out diodes incorporated?s definitions of halogen - and antimony-free, "green" and lead-free. 3. halogen- and antimony-free "green" products are defined as those which contain <900ppm bromine, <900ppm chlorine (<1500ppm total br + cl) and <1000ppm antimony compounds. typical applications circuit ap65211a l1 4.7 h r1 40.2k r2 13k c5 1 f c2 22 f c1 22 f on off 3 in 5 en 2 sw 6 bst 4 fb 1 gnd input output v out 3.3v v in 12v r3 75k figure 1. typical application circuit
ap65211a document number: ds39744 rev. 1 - 2 2 of 13 www.diodes.com june 2017 ? diodes incorporated ap65211a new product pin descriptions pin number pin name function 1 gnd ground 2 sw power switching output. sw is the switching node that suppli es 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. 3 in power input. in supplies the power to the ic, as well as the step-down converter switches. drive in with a 4. 5v 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. 4 fb 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 0.8v. see setting the output voltage. 5 en 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 resisto r for automatic startup. 6 bs t 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 s witch. functional block diagram internal reference 0.4v 0.8v 1.1v v cc regulator + - + - + - - + 1.1v 0.4v + 0.8v internal ss error amplifier ovp pwm comparator oscillator 500khz + logic - + ref ocp 62pf 650k 1pf s e = 0.9v/t r t = 0.22v/a uvp hs ls 4 5 en fb 1 gnd 2 sw 6 bst 3 in figure 2. typical application circuit
ap65211a document number: ds39744 rev. 1 - 2 3 of 13 www.diodes.com june 2017 ? diodes incorporated ap65211a new product absolute maximum ratings (@t a = +25c, unless otherwise specified.) (note 4) 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 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 cdm charged device model 1 kv notes: 4 . stresses greater than the 'absolute maximum ratings' specified above m ay cause permanent damage to the device. these are stress ratings on ly; functional operation of the device at these or any other conditions e xceeding those indicated in this specification is not implied. device reliability may be affected by exposure to absolute maximum rating conditions for ext ended periods of time. 5 . semiconductor devices are esd sensitive and may be damaged by exposure to esd events. suitable esd precautions should be take n when handling and transporting these devices. thermal resistance (note 6) symbol parameter rating unit ja junction to ambient 1 20 c/w jc junction to case 30 c/w note: 6. device mounted on fr-4 substrate, single-layer pc board, 2oz copper, wi th minimum recommended pad layout. recommended operating conditions (@ t a = +25c, unless otherwise specified.) (note 7) symbol parameter min max unit v in supply voltage 4. 5 18 v t a operating ambient temperature range - 40 +85 c note: 7. the device function is not guaranteed outside of the recommend ed operating conditions.
ap65211a document number: ds39744 rev. 1 - 2 4 of 13 www.diodes.com june 2017 ? diodes incorporated ap65211a new product electrical characteristics (@ t a = +25c, v in = 12v, unless otherwise specified.) symbol parameter test conditions min typ max unit i shdn shutdown supply current v en = 0v 1.0 a i q supply current (quiescent) v en = 2.0v, v fb = 0.85v 0.8 ma r ds(on)1 high-side switch on-resistance (note 8) 160 m ? r ds(on)2 low -side switch on-resistance (note 8) 85 m ? i limit_peak hs peak current limit (note 8) minimum duty cycle , t a = -40c to +85c 3.0 3.5 a i sw_lkg switch leakage current v en = 0v, v sw =12v 1 a f sw oscillator frequency v fb = 0.75v 4 00 500 600 khz d max maximum duty cycle v fb = 700mv 88 92 % t on minimum on -time 90 ns v fb feedback voltage t a = -40c to +85c 776 800 824 mv v en_rising en rising threshold 1.4 1.5 1.6 v v en_falling en falling threshold 1.23 1.32 1.41 v i en en input current v en = 2v 2.85 a v en = 0v 0 a inuv vth v in undervoltage threshold rising 3.7 4.05 4.4 v inuv hys v in undervoltage threshold hysteresis 250 mv t ss soft-start period 1 ms t shdn thermal shutdown (note 8) + 160 c t hys thermal hysteresis (note 8) + 20 c note: 8 . compliance to the datasheet limits is assured by one or more methods: prod uction test, characterization, and/or design.
ap65211a document number: ds39744 rev. 1 - 2 5 of 13 www.diodes.com june 2017 ? diodes incorporated ap65211a new product typical performance characteristics (@ t a = +25c, v in = 12v, v out = 3.3v, l = 4.7h, unless otherwise specified.) vin=7v vin=12v vin=18v vin=4.5v vin=12v vin=18v vin=4.5v vin=12v vin=18v vin=4.5v vin=12v vin=18v
ap65211a document number: ds39744 rev. 1 - 2 6 of 13 www.diodes.com june 2017 ? diodes incorporated ap65211a new product typical performance characteristics (cont. ) (@ t a = +25c, v in = 12v, v out = 3.3v, l = 4.7h, unless otherwise specified.) vin=4.5v vin=12v vin=18v vin=4.5v vin=12v vin=18v vin=4.5v iout=1.5a vin=12v iout=2a vin=18v iout=0a
ap65211a document number: ds39744 rev. 1 - 2 7 of 13 www.diodes.com june 2017 ? diodes incorporated ap65211a new product typical performance characteristics (cont.) (@ t a = +25c, v in = 12v, v out = 3.3v, l = 4.7h, c1 = 22f, c2 = 22f, unless otherwis e specified.) startup through v en 2a load time-500s/div startup through v in 2a load time-500s/div short circuit test time-5ms/div shutdown through v en 2a load time-50s/div shutdown through v in 2a load time-200s/div short circuit recovery time-5ms/div startup through v en 0a load time-500s/div startup through v in 0a load time-500s/div transient response (1 to 2a ) time-100s/div shutdown through v en 0a load time-500ms/div shutdown through v in 0a load time-500ms/div input/output ripple (i o =2 a) time-2s/div vin (12v/div ) vout (3.3v/div ) iout ( 2a /div ) sw (1 0v /div ) v en (5 v/div ) iout ( 2a /div ) sw ( 10v /div ) vout (3.3v/div ) ve n (5 v/div ) vout (3.3v/div ) iout ( 2a /div ) sw (1 0v /div ) vin (12v/div ) vout (3.3v/div ) iout ( 2a /div ) sw (1 0v /div ) vout (2v/div ) iout ( 2a /div ) vout (2v/div ) iout ( 2a /div ) iout ( 1a /div ) vout_ac (200mv/div ) vout_ac (50mv/div ) sw ( 10v /div ) v en (5 v/div ) iout (100ma/div ) sw ( 10v /div ) vout (3.3v/div ) ve n (5 v/div ) vout (3.3v/div ) iout (100ma/div ) sw (1 0v /div ) vin (12v/div ) vout (3.3v/div ) iout (100ma/div ) sw (1 0v /div ) vin (12v/div ) vout (3.3v/div ) iout (100ma/div ) sw (1 0v /div ) il ( 2a /div ) vin_ac (200mv/div )
ap65211a document number: ds39744 rev. 1 - 2 8 of 13 www.diodes.com june 2017 ? diodes incorporated ap65211a new product application information theory of operation the ap65211a is a 2a current mode control, synchronous buck regulator with integrated power mosfets. current mod e control assures excellent line regulation, load regulation, and a wide loop bandwidt h for fast response to load transients. figure 2 depicts the functional block diagram of ap65211a. the operation of one switching cycle can be explained as follow s: the rising edge of the 500khz oscillator clock signal set s the rs flip-flop. its output turns on hs mosfet . when the hs mosfet is on, inductor current starts to inc rease. the current sense amplifier with a gain of 0.22v/a is used to detect the inductor current. since the curre nt mode control is subject to sub-harmonic oscillations th at start at half duty cycle, ramp slope compensation of 0.9v/t is added to the current se nse signal. when the sum of the current sense amplifier output and the slope compensation signal exceeds the ea output voltage, the r s flip-flop is reset and hs mosfet is turned off. t he n synchronous ls mosfet turns on until the next clock cy cle begins. there is a dead time between the hs turn off and ls turn on th at prevents the switches from shooting through across the input supply to ground. if the sum of the current sense amplifier output and th e slope compensation signal does not exceed the ea output, then the falling edge of the oscillator clock resets the flip-flop, and forces the hs mosfet to turn off. the voltage loop is compensated internally. enable the enable (en) input allows the user to control turning on or off the regulator. the ap65211a has an internal pull down resistor on the en pin and when the en is not actively pulled up the part tur ns off. quiescent current above the ?en rising threshold?, the internal regulator is turn ed on and the quiescent current can be measured when v fb > 0.8v. automated no-load and light-load operation the ap65211a operates in light load high efficiency mode dur ing low load current operation. the advantage of this light loa d efficiency mode is lower power losses at no-load and light-load conditions. the ap65 21 1a automatically detects the inductor?s valley current and enters the light load high efficiency mode when value falls below zero ampere. once the inductor ?s valley current exceeds zero ampere, the ap65211a transitions from light load high efficiency mode back to continuous pwm mod e. current limit protection in order to reduce the total power dissipation and to pro tect the application, ap65211a has cycle- by -cycle current limiting implementation. the voltage drop across the internal high-side mosfet is sensed a nd compared with the internally set current limit thresho ld . this voltage drop is sensed at about 30ns after the hs turns on. when th e peak inductor current exceeds the set current limit t hreshold, current limit protection is activated. when the fb voltage pin dropped below 0. 4v, the device enters hiccup mode to periodically resta rt the part. this protection mode greatly reduces the power dissipated on chip and reduces the thermal stress to help protect the device. ap65211a will exit hiccup mode when the over current situation is resolved. undervoltage lockout (uvlo) undervoltage lockout is implemented to prevent the ic from insufficient input voltages . the ap65211a has a uvlo comparator that monitors the input voltage and the internal bandgap reference. if the input voltage falls below 4. 05 v, the ap65211a will disable . in this event, both hs and ls mosfets are turned off . overvoltage protection when the ap65211a fb pin exceeds 115% of the nominal regulation voltage of 0.8v, the overvoltage comparator i s tripped and internal regulator would stop switching. the v out would stay high voltage as tripped point and slowly discharged by output capacitance. thermal shutdown the ap65211a has on-chip thermal protection that prevents da mage to the ic when the die temperature exceeds safe marg ins. it implements a thermal sensing to monitor the operating junction temperature o f the ic. once the die temperature rises to approximately +160c, the thermal protection feature gets activated. the internal thermal se nse circuitry turns the ic off thus preventing the powe r switch from damage. a hysteresis in the thermal sense circuit allows the device to cool down to approximately +120c before the ic is enabled again t hrough soft start. this thermal hysteresis feature prevents undesirable oscillations of th e thermal protection circuit.
ap65211a document number: ds39744 rev. 1 - 2 9 of 13 www.diodes.com june 2017 ? diodes incorporated ap65211a new product application information (cont.) setting the output voltage the output voltage can be adjusted from 0.8v using an external resistor divider. table 1 shows a list of resistor selection for common output voltages. a serial resistor rt is also recommended for improving the system stability, especially for low v out (< 3.3v). an optional c ff of 10 pf to 10 0pf used to boost the phase margin. resistor r1 is selecte d based on a design tradeoff between efficiency and out put voltage accuracy. for high values of r1 there is less current consumption in the feedback network . r1 can be determined by the following equation: ?? ? ?? ? ? ? ? 1 0.8 v r r out 2 1 v out fb r1 r2 r t c ff figure 3. feedback divider network table 1. recommended component selection v out (v) c ff (pf) r1 (k) r2 (k) r t (k) l1 (h) 1.05 10 32.4 300 1.5 1.2 15 30.1 249 1.5 1.8 47 40.2 32.4 120 2.2 2.5 47 40.2 19.1 100 2.2 3.3 47 40.2 13 75 4.7 5 47 40.2 7.68 75 6. 8 inductor calculating the inductor value is a critical factor in designing a bu ck converter. for most designs, the following equation can b e used to calculate the inductor value; sw l in out in out f i v ) v (v v l ? ? ? ? ? where l i is the inductor ripple current and f sw is the buck converter switching frequency. choose the inductor ripple current to be 30% to 40% of th e maximum load current. the maximum inductor peak current is calculated from: 2 i i i l load l(max) ? ? peak current determines the required saturation current rating, which influences the size of the inductor. saturating t he inductor decreases the converter efficiency while increasing the temperatures o f the inductor and the internal mosfets. hence, choose an inductor with appropriate saturation current rating is important. a 1h to 10h inductor with a dc current rating of at leas t 25% higher than the maximum load current is recommended f or most applications. for highest efficiency, the inductor?s dc resistance should be less than 20m? . use a larger inductance for improved efficiency under ligh t load conditions. input capacitor the input capacitor reduces the surge current drawn from the input supply and the switching noise from the device. the input capacitor has to sustain the ripple current produced during the on time on the upper mosfet. it must hence have a low esr to minimize t he losses. the rms current rating of the input capacitor is a critica l parameter that must be higher than the rms input curr ent. as a rule of thumb, select an input capacitor which has rms rating that is greater th an half of the maximum load current. due to large di /dt through the input capacitors, low r esr electrolytic or ceramics should be used. if a tantalum m ust be used, it must be surge protected. otherwise, capacitor failure could occur. for m ost applications, a 22f ceramic capacitor is sufficient. output capacitor the output capacitor keeps the output voltage ripple small, ensures feedback loop stability and reduces the oversh oot of the output voltage. the output capacitor is a basic component for the fast r esponse of the power supply. during load transient, the ou tput capacitor supplies the current to the load for the first few cycles. this caused the output voltage to drop and sets the duty cycle to maximum, but the current slope is limited by the inductor value. maximum capacitance required can be calculated from the fo llowing equation:
ap65211a document number: ds39744 rev. 1 - 2 10 of 13 www.diodes.com june 2017 ? diodes incorporated ap65211a new product application information (cont.) esr of the output capacitor dominates the output vol tage ripple. the amount of ripple can be calculated from the eq uation below: esr * i vout inductor ripple ? an output capacitor with high capacitance and low esr is the best option. for most applications, a 22f ceramic capac itor 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. pc board layout the layout is very important in high frequency switching con verter design. with power devices switching efficiently at 500khz, the resulting current transitions from one device to another cause voltage sp ikes across the interconnecting impedances and parasitic circ uit elements. these voltage spikes can degrade efficiency, radiate noise into the circuit , and lead to device overvoltage stress. careful compone nt layout and printed circuit board design minimizes these voltage spikes. as an examp le, consider the turn-off transition of the h s mosfet. prior to turn-off, the hs mosfet is carrying the full load current. during turn-off, c urrent stops flowing in the hs mosfet and is picked up by the internal body diode. any parasitic inductance in the switched current path gene rates a large voltage spike during the switching interval. car eful component selection, tight layout of the critical components and short, wide tra ces minimize the magnitude of voltage spikes. there are two sets of critical components in the regulator switching converter. the switching components a re the most critical because they switch large amounts o f energy and therefore tend to generate large amounts of noise. next are the small signal components, which connect to sensitive nodes for controlling the regulator. the switching components should be placed close to the regulat or first. minimize the length of the connections between the input capacitors and the power switches by placing them nearby. position both t he ceramic and bulk input capacitors as close to the uppe r mosfet drain as possible. the critical small signal components include feedback components an d bst capacitor. place the compensation components close to the fb pin . the feedback resistors should be located as close as pos sible to the fb pin with vias tied straight to the ground plane. see figure 4 for reference. figure 4. pc board layout external bootstrap diode it is recommended that an external bootstrap diode be ad ded when the input voltage is no greater than 5v or th e 5v rail is available in the system. this helps to improve the efficiency of the regulator. this so lution is also applicable for d > 65%. the bootstrap diode ca n be a low cost device such as b130 or a schottky diode that has a low v f . see below for diodes incorporated?s recommended diodes. ap65211a bst sw 10nf boost diode 5v figure 5. external bootstrap compensation components recommended diodes: part number voltage/current rating b130 30v, 1a sk13 30v, 1a
ap65211a document number: ds39744 rev. 1 - 2 11 of 13 www.diodes.com june 2017 ? diodes incorporated ap65211a new product ordering information (note 9) ap65211a x - x packing package wu : tsot26 7 : tape & reel part number package code pa ckage identification code tape and reel quantity part number suffix ap65211a wu -7 wu tsot26 r4 3, 000 -7 note: 9. for packaging details, go to our website at https://www.diodes.com/de sign/support/packaging/diodes-packaging/. marking information tsot26 1 2 3 6 7 4 xx y w x xx : identification code y : year 0~9 x : internal code (top view) 5 w : week : a~z : 1~26 week; a~z : 27~52 week; z represents 52 and 53 week part number package identification code ap65211a wu -7 tsot26 r4
ap65211a document number: ds39744 rev. 1 - 2 12 of 13 www.diodes.com june 2017 ? diodes incorporated ap65211a new product package outline dimensions please see http://www.diodes.com/package-outlines.html for the latest version. tsot26 suggested pad layout please see http://www.diodes.com/package-outlines.html for the latest version. tsot26 tsot26 dim min max typ a ? 1.00 ? a1 0.010 0.100 ? a2 0.840 0.900 ? d 2.800 3.000 2.900 e 2.800 bsc e1 1.500 1.700 1.600 b 0.300 0.450 ? c 0.120 0.200 ? e 0.950 bsc e1 1.900 bsc l 0.30 0.50 ? l2 0.250 bsc 0 8 4 1 4 12 ? all dimensions in mm dimensions value (in mm) c 0.950 x 0.700 y 1.000 y1 3.199 d e1 e1/2 e1 e e/2 e a a2 a1 seating plane 0 l2 l gauge plane 01( 4x) 01( 4x) c b seating plane y1 c x y
ap65211a document number: ds39744 rev. 1 - 2 13 of 13 www.diodes.com june 2017 ? diodes incorporated ap65211a new product important notice diodes incorporated makes no warranty of any kind, expres s or implied, with regards to this document, including, but not limited to, the implied warranties of me rchantability and fitness for a particular purpose (and their equivalents under the laws of any jurisdiction) . diodes incorporated and its subsidiaries reserve the right to make modifications, enhancements, improvements, correction s or other changes without further notice to this document and any produ ct described herein. diodes incorporated does not assume any liability arising out of the application or use of this document or any product des cribed herein; neither does diodes incorporated convey a ny license under its patent or trademark rights, nor the rights of others. any custome r or user of this document or products described here in in such applications shall assume all risks of such use and will agree to hold diodes incorpo rated and all the companies whose products are represe nted on diodes incorporated website, harmless against all damages . diodes incorporated does not warrant or accept any lia bility whatsoever in respect of any products purchased through unauthorized sales channel. should customers purchase or use diodes incorporated prod ucts for any unintended or unauthorized application, cus tomers shall indemnify and hold diodes incorporated and its representatives harmless against all claims, damages, expenses, and attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized application. products described herein may be covered by one or more united states, international or foreign patents pending. pro duct names and markings noted herein may also be covered by one or more unite d states, international or foreign trademarks. this document is written in english but may be translated int o multiple languages for reference. only the english version of this document is the final and determinative format released by diodes incorporat ed. life support diodes incorporated products are specifically not auth orized for use as critical components in life support dev ices or systems without the express written approval of the chief executive officer of diodes i ncorporated. as used herein: a . life support devices or systems are devices or syste ms which: 1. are intended to implant into the body, or 2. support or sustain life and whose failure to perfor m when properly used in accordance with instructions for u se provided in the labeling can be reasonably expected to result in signi ficant injury to the user. b . a critical component is any component in a life suppo rt device or system whose failure to perform can be re asonably expected to cause the failure of the life support device or to affect i ts safety or effectiveness. customers represent that they have all necessary exp ertise in the safety and regulatory ramifications of their lif e support devices or systems, and acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concern ing their products and any use of diodes incorporated products in such safety-criti cal, life support devices or systems, notwithstanding any devices- or systems-related information or support that may be provided by diodes incorpo rated. further, customers must fully indemnify diodes incor porated and its representatives against any damages arising out of the u se of diodes incorporated products in such safety-critic al, life support devices or systems. copyright ? 201 7, diodes incorporated www.diodes.com

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