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ait semiconductor inc. www.ait - ic.com A7533 0.85v startup, 1mhz, 300ma i out synchronus boost step - up dc - dc converter rev1. 1 - jul 2010 released , j ul 201 1 revised - - 1 - description features the A7533 is a step - up converter that provides a boosted output voltage from a low voltage source. because of its proprietary design, it starts up at a very low input voltage down to 850mv, making it an ideal choice for single cell a lkaline/ nimh battery operations. a switching frequency of 1mhz minimizes solution footprint by allowing the use of tiny, low profile inductors and ceramic capacitors. the current mode pwm design is internally compensated, reducing external parts count. the A7533 is avai lable in sot - 25 and sot - 89- 3 packag e . ? up to 95% efficiency ? output voltage accuracy 3 % ? 1mhz switching frequency allows small inductor and output cap ? input boost - strapping allows using small or no input cap ? low v in start - up voltage down t o 850mv ideal for single alkaline cell operations ? maximum output current up to 300ma ? low noise pwm control ? internally compensated current mode control ? internal synchronous rectifier ? logic control shutdown (iq < 1ua) ? available in sot - 25 and sot - 89- 3 pac kage . order information package type part number sot - 25 e 5 A7533e5 r - xx A7533e5 vr - xx sot - 89- 3 k3 A7533k3r - xx A7533k3vr - xx note xx =output , adj=adjustable v: green package r : tape & reel ait provides all pb free products suffix v means green p ackage application ? one to three cell battery operated devices ? medical instruments ? bluetooth headsets ? flash - based mp3 players ? noise canceling headphones typical application note: input ca pacitor (c in = 0.4 7 uf) and output capacitor (c out 4.7uf) are recommended in all application circuit.
ait semiconductor inc. www.ait - ic.com A7533 0.85v startup, 1mhz, 300ma i out synchronus boost step - up dc - dc converter rev1. 1 - jul 2010 released , j ul 201 1 revised - - 2 - pin description top v iew top v iew pin # symbo l function sot - 2 5 sot - 89 - 3 1 - fb feedback input pin 2 1 g nd ground pin 3 - e n chip enable pin 4 3 sw power switch pin 5 2 out power output pin
ait semiconductor inc. www.ait - ic.com A7533 0.85v startup, 1mhz, 300ma i out synchronus boost step - up dc - dc converter rev1. 1 - jul 2010 released , j ul 201 1 revised - - 3 - absolute maximum ratings sw voltage - 0.3v to +6v - 0.3v to +6v en, fb, out voltage jun c tion to ambient thermal resistance 190 /w maximum power dissipation 0.45 w operating temperat ure range - 40 ~ 150 storage temperature - 55 ~ 150 ir reflow lead temperature and time 260 stresses above may cause permanent damage to the device. t hese are stress ratings only, and functional operation of the device at these or any other con ditions beyond those indicated in the electrical characteristics is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. , 10s
ait semiconductor inc. www.ait - ic.com A7533 0.85v startup, 1mhz, 300ma i out synchronus boost step - up dc - dc converter rev1. 1 - jul 2010 released , j ul 201 1 revised - - 4 - electrical characteristics test condition: v in =1.8v, v out =3.3v, t a =25 , u nless otherwise specified. parameter conditions min typ max unit minimum input voltage - 0.7 - v startup voltage - 0.85 1.1 v dropout voltage, v out 2.8v - fb = ou t 3.3 - v - fb = g nd 5 - v fb feedback voltage v out - = 2.5 to 5v 0.6 - v fb input current - - 50 na output voltage range 2.5 external divider - 5 v quiescent current at out v fb - = 0.7v 25 - a shutdown supply current at out - en = g 0.1 1 a nmos switch on resistance i sw - = 100ma 0.3 - ohm pmos switch on resistance i sw - = 100ma 0.7 - ohm nmos switch current limit 1 - - a sw leakage current v out = 5.5v, v sw - = 0 or 5.5v, en = g nd - 1 ua en input current - - 1 ua en input voltage for low - - 0.3 v en input voltage for high 0.6 - - v
ait semiconductor inc. www.ait - ic.com A7533 0.85v startup, 1mhz, 300ma i out synchronus boost step - up dc - dc converter rev1. 1 - jul 2010 released , j ul 201 1 revised - - 5 - typical performance characteri stics typical values are tested at t a = 25 , unless otherwise specified. 1. efficiency vs . output current v out = 3.3v , t a = 25 2. e fficiency vs . output current v out = 5v , t a = 25 3. output voltage vs. output current v out = 3.3v , t a = 25 4. minimum start - up voltage vs. output current v out = 3.3v , t a = 25 5. maximum output current vs. input voltage l = 4.7uh , t a = 25 6. no load input current vs. input voltage v out = 3.3v , t a = 25 , no l oad
ait semiconductor inc. www.ait - ic.com A7533 0.85v startup, 1mhz, 300ma i out synchronus boost step - up dc - dc converter rev1. 1 - jul 2010 released , j ul 201 1 revised - - 6 - 7. v ref (t) / v ref 8. output voltage vs. tem p erature (t = 20 ) vs. temperature 9. frequency vs. temperature
ait semiconductor inc. www.ait - ic.com A7533 0.85v startup, 1mhz, 300ma i out synchronus boost step - up dc - dc converter rev1. 1 - jul 2010 released , j ul 201 1 revised - - 7 - block diagram
ait semiconductor inc. www.ait - ic.com A7533 0.85v startup, 1mhz, 300ma i out synchronus boost step - up dc - dc converter rev1. 1 - jul 2010 released , j ul 201 1 revised - - 8 - detail information A7533 is a low input voltage start up, current mode dc- dc step up converter. it s operation can be best understood by referring to the block diagram. upon starting up, the low voltage startup circuitry drives sw with on - off cycles, transferring energy from input to out by s toring energy i n the inductor during on - time and releasing it to the output during off - time. when out reaches 2v, the startup circuit turns off and the main controller takes over. the main control loop consists of a reference, a gm error amplif ier, a pwm controller, a current sense amplifier, an oscillator, a pwm logic control, and it is power stage including its driver. the main control loop is a classic current mode control loop. the gm stage integrates the error between fb and ref, and its ou tput is used to compare with a triangular wave which the summing result of the current sense amplifier output and a slope compensation voltage. the output of the comparator is used to drive the power stage to reach regulation. output voltage selection the output voltages can be set by connecting fb to out, to g or to the midpoint of a resistor divider connected to out. see below table for details. fb = g nd v out = 5.0v fb = out v out = 3.3v fb to resistor divider v out inductor selection with switching frequency up to 1mhz, small surface mount inductors can be used with values from 2.2uh to 4.7uh. for a given chosen inductor value and application conditions make sure the peak inductor current does not exceed the maximum current rating of t he selected vendor's inductor. input and output capacitor selection the A7533 's bootstrap architecture allows the use of very small input capacitor. for applications that only need to drive small output load current, the input capacitor is optional, becau se once output is started up, the ic's is powered by out, a quiet power supply. the output capacitor is used to stabilize the loop and provide ac current to the load. a low esr ceramic cap with values from 2.2uf to 22uf can be used. smaller value capacito rs are generally cheaper with small footprints, while larger capacitor provides lower ripples and better transient load responses. also, when extreme low startup voltage is needed, larger output capacitors are needed for the part to startup under heavy loa d condition. = 0.6v(1+r1/r2)
ait semiconductor inc. www.ait - ic.com A7533 0.85v startup, 1mhz, 300ma i out synchronus boost step - up dc - dc converter rev1. 1 - jul 2010 released , j ul 201 1 revised - - 9 - package information dimension in sot - 25 package (unit: mm) symbol min max a 1.050 1.250 a1 0.000 0.100 a2 1.050 1.150 b 0.300 0.500 c 0.100 0.200 d 2.820 3.020 e 1.500 1.700 e1 2.650 2.950 e 0.950(bsc) e1 1.800 2.000 l 0.300 0.600 0 8
ait semiconductor inc. www.ait - ic.com A7533 0.85v startup, 1mhz, 300ma i out synchronus boost step - up dc - dc converter rev1. 1 - jul 2010 released , j ul 201 1 revised - - 10 - dimension in s ot - 89 - 3 (unit: mm) symbol min max a 1.400 1.600 b 0.320 0.520 b1 0.400 0.580 c 0.350 0.440 d 4.400 4.600 d1 1.550 ref e 2.300 2.600 e1 3.940 4.250 e 1.500 typ e1 3.000 typ l 0.900 1.200
ait semiconductor inc. www.ait - ic.com A7533 0.85v startup, 1mhz, 300ma i out synchronus boost step - up dc - dc converter rev1. 1 - jul 2010 released , j ul 201 1 revised - - 11 - important notice a it semiconductor inc. (ait) reserves the right to make changes to any its pr oduct, specifications, to disco ntinue any integrated circuit product or service w i thout notice, and advises its customers to obtain the latest version of relevant information to ve rify, before placing orders, that the information being relied on is current. a it semiconductor inc. 's integrated circuit products are not designed, intended, authorized, or warranted to be suitable for use in life support applications, devices or system s or other critical applications. use of ait products in such applications is understood to be fully at the risk of the customer. as used herein may involve potential risks of death, personal injury, or servere property, or environmental damage. in or der to minimize risks associated with the customer's appli c ations, the customer should provide adequate design and operating safeguards. a it semiconductor inc. assumes to no liability to customer product design or application support. ait warrants the p erformance of its products o f the specifications applicable at the time of sale.

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