View AUR9721_8302487.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

data sheet 5v, 2a, 1.5mhz, step-down dc-dc converter AUR9721 aug. 2012 rev. 1.0 bcd semiconductor manufacturing limited 1 general description the AUR9721 is a high efficiency step-down dc-dc voltage converter. the chip operation is optimized by peak-current mode architecture with built-in synchronous power mos switchers. the oscillator and timing capacitors are all built-in providing an internal switching frequency of 1.5mhz that allows the use of small surface mount inductors and capacitors for portable product implementations. additional features including soft start (ss), under voltage lock out (uvlo), thermal shutdown detection (tsd) and short circuit protection are integrated to provide reliable product applications. the device is available in adjustable output voltage versions ranging from 0.8v t o 0.9 v in w hen input voltage range is from 2.7v to 5.5v, and is able to deliver up to 2a. the AUR9721 is available in dfn-33-10 package. features ? high efficiency buck power converter ? output current: 2a ? adjustable output voltage from 0.8v to 0.9 v in ? wide operating voltage range: 2.7v to 5.5v ? built-in power switches for synchronous rectification with high efficiency ? feedback voltage allows output: 800mv ? 1.5mhz switching frequency ? thermal shutdown protection ? low drop-out operation at 90% duty cycle ? no schottky diode required applications ? lcd tv ? set top box ? post dc-dc voltage regulation ? pci card ? pda and notebook computer figure 1. package type of AUR9721 dfn-33-10
data sheet 5v, 2a, 1.5mhz, step-down dc-dc converter AUR9721 aug. 2012 rev. 1.0 bcd semiconductor manufacturing limited 2 pin configuration d package (dfn-33-10) figure 2. pin configuration of AUR9721 (top view) pin description pin number pin name function 1 fb feedback voltage from th e output of the power supply 2, 9 gnd this pin is the gnd reference for the nmosfet power stage. it must be connected to the system ground 3, 8 sw connected to inductor 4, 7 vin power supply input 5, 6 nc no internal connection 10 en enable signal input, active high
data sheet 5v, 2a, 1.5mhz, step-down dc-dc converter AUR9721 aug. 2012 rev. 1.0 bcd semiconductor manufacturing limited 3 functional block diagram figure 3. functional block diagram of AUR9721 ordering information AUR9721 circuit type a: adjustable output package temperature range part number marking id packing type dfn-3 3-10 -40 to 80c AUR9721agd 9721a tape & reel bcd semiconductor's pb-free products, as designated with "g" in the part number, are rohs compliant and green. package d: dfn-33-10 g: green
data sheet 5v, 2a, 1.5mhz, step-down dc-dc converter AUR9721 aug. 2012 rev. 1.0 bcd semiconductor manufacturing limited 4 absolute maximum ratings (note 1) parameter symbol value unit supply input voltage v in 0 to 6.0 v enable input voltage v en -0.3 to v in +0.3 v switch output voltage v sw -0.3 to v in +0.3 v power dissipation (on 4 layer pcb, t a =25c) p d 2.2 w thermal resistance (junction to ambient, simulation) ja 45 c/w operating junction temperature t j 150 c operating temperature t op -40 to 85 c storage temperature t stg -55 to 150 c esd (human body model) v hbm 2000 v esd (machine model) v mm 200 v note 1: stresses greater than those listed under ?absolute maximum ratings? may cause permanent damage to the device. these are stress ratings only, and functional op eration of the device at these or any other conditions beyond those indicated under ?recommended operating co nditions? is not implied. exposure to ?absolute maximum ratings? for extended periods may affect device reliability. recommended operating conditions parameter symbol min max unit supply input voltage v in 2.7 5.5 v junction temperature range t j -40 125 c ambient temperature range t a -40 80 c
data sheet 5v, 2a, 1.5mhz, step-down dc-dc converter AUR9721 aug. 2012 rev. 1.0 bcd semiconductor manufacturing limited 5 electrical characteristics v in =v en =5v, v fb =0.8v, l=1.2 h, c in =47 f, c out =47 f, t a =25c, unless otherwise specified. parameter symbol conditions min typ max unit input voltage range v in 2.7 5.5 v shutdown current i off v en =0v 0.1 1 a active current i on v fb =0.95v 460 a regulated feedback voltage v fb for adjustable output voltage 0.784 0.8 0.816 v regulated output voltage accuracy ? v out /v out v in =2.7v to 5.5v, i out =10ma to 2a -3 3 % peak inductor current i pk 2.2 3.2 a oscillator frequency f osc 1.2 1.5 1.8 mhz pmosfet r on r on(p) i sw =0.75a 100 m ? nmosfet r on r on(n) i sw =0.75a 100 m ? en input current i en 2 a en high-threshold input voltage v en_h 1.5 v en low-threshold input voltage v en_l 0.4 v soft start time t ss 800 s maximum duty cycle d max 90 % under voltage lock out threshold v uvlo rising 2.4 v falling 2.3 hysteresis 0.1 thermal shutdown t sd hysteresis=30c 150 c
data sheet 5v, 2a, 1.5mhz, step-down dc-dc converter AUR9721 aug. 2012 rev. 1.0 bcd semiconductor manufacturing limited 6 typical performance characteristics figure 4. output current vs. efficiency figure 5. output current vs. efficiency figure 6. output current vs. efficiency
data sheet 5v, 2a, 1.5mhz, step-down dc-dc converter AUR9721 aug. 2012 rev. 1.0 bcd semiconductor manufacturing limited 7 typical performance characteristics (continued) figure 7. output ripple figure 8. output ripple (v in =5v, v out =1.2v, i out =2a) (v in =5v, v out =3.3v, i out =2a) figure 9. power on (v in =5v, v out =1.2v) v out 10mv/div v sw 50v/div time 1 s/div v in 2v/div v out 1v/div v sw 5v/div v out 10mv/div v sw 50v/div time 2 s/div i out 1a/div time 1ms/div
data sheet 5v, 2a, 1.5mhz, step-down dc-dc converter AUR9721 aug. 2012 rev. 1.0 bcd semiconductor manufacturing limited 8 application information the basic AUR9721 application circuit is shown in figure 11. external components selection is determined by the load current and is critical with the selection of inductor and capacitor values. 1. inductor selection for most applications, the value of inductor is chosen based on the required ripple current with the range of 1.0 h to 6.8 h. the largest ripple current occurs at the highest input voltage. having a small ripple current reduces the esr loss in the output capacitor and improves the efficiency. the highest efficiency is realized at low operating frequency with small ripple current. however, larger value inductors will be required. a reasonable starting point for ripple current setting is i l =40%i max ? . for a maximum ripple current stays below a specified value, the inductor should be chosen according to the following equation: the dc current rating of the inductor should be at least equal to the maximum output current plus half the highest ripple current to prevent inductor core saturation. for better efficiency, a lower dc-resistance inductor should be selected. 2. capacitor selection the input capacitance, c in , is needed to filter the trapezoidal current at the source of the top mosfet. to prevent large ripple voltage, a low esr input capacitor sized for the maximum rms current must be used. the maximum rm s capacitor current is given by: it indicates a maximum value at v in =2v out , where i rms =i out /2. this simple wors e-case condition is commonly used for design because even significant deviations do not much relieve. the selection of c out is determined by the effective series resistance (esr) that is required to minimize output voltage ripple and load step transients, as well as the amount of bulk capacitor that is necessary to ensure that the control loop is stable. the output ripple, v out , is determined by: the output ripple is the highest at the maximum input voltage since i l increases with input voltage. 3. load transient a switching regulator typically takes several cycles to respond to the load curren t step. when a load step occurs, v out immediately shifts by an amount equal to i load esr, where esr is the effective series resistance of output capacitor. i load also begins to charge or discharge c out generating a feedback error signal used by the regulator to return v out to its steady-state value. during the recovery time, v out can be monitored for overshoot or ringing that would indicate a stability problem. 4. output voltage setting the output voltage of AUR9721 can be adjusted by a resistive divider according to the following formula: the resistive divider senses the fraction of the output voltage as shown in figure 10. figure 10. setting the output voltage in out in out omax rms v v v v i i 2 1 )] ( [ ? = ) 1 ( 1 in out out l v v v l f i ? = ? ] ) ( 1 ][ ) ( [ max v v max i f v l in out l out ? ? = ] 8 1 [ out l out c f esr i v + ? ? ) 1 ( 8 . 0 ) 1 ( 2 1 2 1 fb r r v r r v v out + = + = fb gnd vout r1 r2 aur 9721
data sheet 5v, 2a, 1.5mhz, step-down dc-dc converter AUR9721 aug. 2012 rev. 1.0 bcd semiconductor manufacturing limited 9 application information (continued) 5. short circuit protection when the output node is shorted to gnd, as v fb drops under 0.4v, the chip will enter soft-start to protect itself; when short circuit is removed, and v fb rises over 0.4v, AUR9721 will enter normal operation again. if the chip reaches ocp threshold while short circuited, it will enter soft-start cycle until the current drops under ocp threshold. 6. efficiency considerations the efficiency of switching regulator is equal to the output power divided by the input power times 100%. it is usually useful to analyze the individual losses to determine what is limiting efficiency and which change could produce the largest improvement. efficiency can be expressed as: efficiency=100%-l1-l2-?.. where l1, l2, etc, are the individual losses as a percentage of input power. although all dissipative elements in the regulator produce losses, two major sources usually account for most of the power losses: v in quiescent current and i 2 r losses. the v in quiescent current loss dominates the efficiency loss at very light load currents and the i 2 r loss dominates the efficiency loss at medium to heavy load currents. 6.1 the v in quiescent current loss comprises two parts: the dc bias current as given in the electrical characteristics and the internal mosfet switch gate charge currents. the gate charge current results from switching the gate capacitance of the internal power mosfet switches. each cycle the gate is switched from high to low, then to high again, and the packet of charge, dq moves from v in to ground. the resulting dq/dt is the current out of v in that is typically larger than the internal dc bias current. in continuous mode, where q p and q n are the gate charge of power pmosfet and nmosfet switches. both the dc bias current and gate charge losses are proportional to the v in and this effect will be more serious at higher input voltages. 6.2 i 2 r losses are calculated from internal switch resistance, r sw and external inductor resistance r l . in continuous mode, the average output current flowing through the inductor is chopped between power pmosfet switch and nmosfet switch. then, the series resistance looking into the sw pin is a function of both pmosfet r ds(on)p and nmosfet r ds(on)n resistance and the duty cycle (d): therefore, to obtain the i 2 r losses, simply add r sw to r l and multiply the result by the square of the average output current. other losses including c in and c out esr dissipative losses and inductor core losses generally account for less than 2% of total additional loss. 7. thermal characteristics in most applications, the part does not dissipate much heat due to its high efficiency. however, in some conditions when the part is operating in high ambient temperature with high r ds(on) resistance and high duty cycles, the heat dissipated may exceed the maximum junction temperature. to avoid the part from exceeding maximum junction temperature, the user should do some ther mal analysis. the maximum power dissipation depends on the layout of pcb, the thermal resistance of ic package, the rate of surrounding airflow and the temperature difference between junction and ambient. 8. pc board layout considerations when laying out the printed circuit board, the following checklist should be used to optimize the performance of AUR9721. 1. the power traces, including the gnd trace, the sw trace and the vin trace should be kept direct, short and wide. 2. put the input capacitor as close as possible to the vin and gnd pins. 3. the fb pin should be connected directly to the feedback resistor divider. 4. keep the switching node sw away from the sensitive fb pin and the node should be kept small area. ) ( n p gate q q f i + = () () ) ( d r d r r n on ds p on ds sw ? + = 1
data sheet 5v, 2a, 1.5mhz, step-down dc-dc converter AUR9721 aug. 2012 rev. 1.0 bcd semiconductor manufacturing limited 10 typical application v in = 2.7 v to 5.5v fb AUR9721 sw gnd en vin i r2 nc gnd sw vin nc c in 47 f c1 r1 r2 v out c out 47 f 2 3 47 8 9 10 1 note 2: ) 1 ( 2 1 r r v v fb out + = ; v fb =0.8v when r2=400k ? to 80k ? , the i r2 =2 a to 10 a, and r 1 c1 should be in the range between 310 -6 and 610 -6 for component selection. figure 11. typical application circuit of AUR9721
data sheet 5v, 2a, 1.5mhz, step-down dc-dc converter AUR9721 aug. 2012 rev. 1.0 bcd semiconductor manufacturing limited 11 mechanical dimensions dfn-33-10 unit: mm(inch) 2.900(0. 114) 3.100(0.122) 2.900(0. 114) 3.100(0. 122) 1.600(0. 063) 1.800(0. 071) 0.200(0. 008) 0.300(0. 012) 0.500(0. 020) typ 0.300(0. 012) 0.500(0. 020) 0.000(0. 000) 0.050(0. 002) 0.700(0.028) 0.800(0. 031) 0.153(0. 006) 0.253(0. 010) 2.300(0. 090) 2.500(0. 098) n1 n5 n6 n10 pin 1 mark pin #1 identification see detail a 1 2 detail a 1 2 1 2 pin 1 options
important notice bcd semiconductor manufacturing limited reserves the right to make changes without further not ice to any products or specifi- cations herein. bcd semiconductor manufacturing limited does not as sume any responsibility for us e of any its products for any particular purpose, nor does bcd semiconductor manufacturi ng limited assume any liability aris ing out of the application or use of any its products or circui ts. bcd semiconductor manufacturing limited does not convey any license under its patent rights or other rights nor the rights of others. - wafer fab shanghai sim-bcd semiconductor manufacturing co., ltd. 800 yishan road, shanghai 200233, china tel: +021-6485-1491, fa x: +86-021-5450-0008 main site regional sales office shenzhen office shanghai sim-bcd semiconductor manu facturing co., ltd., shenzhen office unit a room 1203,skyworth bldg., gaoxin ave.1.s., nanshan district shenzhen 518057, china tel: +86-0755-8660-4900, fax: +86-0755-8660-4958 taiwan office (taipei) bcd semiconductor (taiwan) company limited 3f, no.17, lane 171, sec. 2, jiu-zong rd., ne i-hu dist., taipei(114), taiwan, r.o.c tel: +886-2-2656 2808 fax: +886-2-2656-2806/26562950 taiwan office (hsinchu) bcd semiconductor (taiwan) company limited 8f, no.176, sec. 2, gong-dao 5th road, east district hsinchu city 300, taiwan, r.o.c tel: +886-3-5160181, fax: +886-3-5160181 - headquarters bcd (shanghai) micro-electronics limited no. 1600, zi xing road, shanghai zizhu scie nce-based industrial park, 200241, p. r.c. tel: +86-021-2416-2266, fax: +86-021-2416-2277 usa office bcd semiconductor corp. 48460 kato road, fremont, ca 94538, usa tel: +1-510-668-1950 fax: +1-510-668-1990 korea office bcd semiconductor limited korea office. room 101-1112, digital-empire ii, 486 sin-dong, yeongtong-gu, suwon-city, gyeonggi-do, korea tel: +82-31-695-8430 important notice bcd semiconductor manufacturing limited reserves the right to make changes without further not ice to any products or specifi- cations herein. bcd semiconductor manufacturing limited does not as sume any responsibility for us e of any its products for any particular purpose, nor does bcd semiconductor manufacturi ng limited assume any liability aris ing out of the application or use of any its products or circui ts. bcd semiconductor manufacturing limited does not convey any license under its patent rights or other rights nor the rights of others. - wafer fab shanghai sim-bcd semiconductor manufacturing limited 800, yi shan road, shanghai 200233, china tel: +86-21-6485 1491, fax: +86-21-5450 0008 bcd semiconductor manufacturing limited main site regional sales office shenzhen office shanghai sim-bcd semiconductor manuf acturing co., ltd. shenzhen office advanced analog circuits (shanghai) corporation shenzhen office room e, 5f, noble center, no.1006, 3rd fuzhong road, futian district, shenzhen 518026, china tel: +86-755-8826 7951 fax: +86-755-8826 7865 taiwan office bcd semiconductor (taiwan) company limited 4f, 298-1, rui guang road, nei-hu district, taipei, taiwan tel: +886-2-2656 2808 fax: +886-2-2656 2806 usa office bcd semiconductor corporation 30920 huntwood ave. hayward, ca 94544, u.s.a tel : +1-510-324-2988 fax: +1-510-324-2788 - ic design group advanced analog circuits (shanghai) corporation 8f, zone b, 900, yi shan road, shanghai 200233, china tel: +86-21-6495 9539, fax: +86-21-6485 9673 bcd semiconductor manufacturing limited http://www.bcdsemi.com bcd semiconductor manufacturing limited important notice bcd semiconductor manufacturing limited reserves the right to make changes without further not ice to any products or specifi- cations herein. bcd semiconductor manufacturing limited does not as sume any responsibility for us e of any its products for any particular purpose, nor does bcd semiconductor manufacturi ng limited assume any liability aris ing out of the application or use of any its products or circui ts. bcd semiconductor manufacturing limited does not convey any license under its patent rights or other rights nor the rights of others. - wafer fab shanghai sim-bcd semiconductor manufacturing co., ltd. 800 yi shan road, shanghai 200233, china tel: +86-21-6485 1491, fax: +86-21-5450 0008 main site regional sales office shenzhen office shanghai sim-bcd semiconductor manuf acturing co., ltd., shenzhen office unit a room 1203, skyworth bldg., gaoxin ave.1.s., nanshan district, shenzhen, china tel: +86-755-8826 7951 fax: +86-755-8826 7865 taiwan office bcd semiconductor (taiwan) company limited 4f, 298-1, rui guang road, nei-hu district, taipei, taiwan tel: +886-2-2656 2808 fax: +886-2-2656 2806 usa office bcd semiconductor corp. 30920 huntwood ave. hayward, ca 94544, usa tel : +1-510-324-2988 fax: +1-510-324-2788 - headquarters bcd semiconductor manufacturing limited no. 1600, zi xing road, shanghai zizhu sc ience-based industrial park, 200241, china tel: +86-21-24162266, fax: +86-21-24162277 important notice bcd semiconductor manufacturing limited reserves the right to make changes without further not ice to any products or specifi- cations herein. bcd semiconductor manufacturing limited does not as sume any responsibility for us e of any its products for any particular purpose, nor does bcd semiconductor manufacturi ng limited assume any liability aris ing out of the application or use of any its products or circui ts. bcd semiconductor manufacturing limited does not convey any license under its patent rights or other rights nor the rights of others. - wafer fab shanghai sim-bcd semiconductor manufacturing limited 800, yi shan road, shanghai 200233, china tel: +86-21-6485 1491, fax: +86-21-5450 0008 bcd semiconductor manufacturing limited main site regional sales office shenzhen office shanghai sim-bcd semiconductor manuf acturing co., ltd. shenzhen office advanced analog circuits (shanghai) corporation shenzhen office room e, 5f, noble center, no.1006, 3rd fuzhong road, futian district, shenzhen 518026, china tel: +86-755-8826 7951 fax: +86-755-8826 7865 taiwan office bcd semiconductor (taiwan) company limited 4f, 298-1, rui guang road, nei-hu district, taipei, taiwan tel: +886-2-2656 2808 fax: +886-2-2656 2806 usa office bcd semiconductor corporation 30920 huntwood ave. hayward, ca 94544, u.s.a tel : +1-510-324-2988 fax: +1-510-324-2788 - ic design group advanced analog circuits (shanghai) corporation 8f, zone b, 900, yi shan road, shanghai 200233, china tel: +86-21-6495 9539, fax: +86-21-6485 9673 bcd semiconductor manufacturing limited http://www.bcdsemi.com bcd semiconductor manufacturing limited

▲Up To Search▲

Price & Availability of AUR9721

	To Download AUR9721 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .