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| product structure : silicon monolithic integrated c ircuit this product is not designed protection against rad ioactive rays 1/11 tsz02201-0f2f0ag00020-1- 2 ? 2012 rohm co., ltd. all rights reserved. 21.jun.2012 rev.001 www.rohm.com tsz22111 14 001 datasheet single-chip type with built-in fet switching regula tor series step-down switching regulators with built-in power mosfet bu9002xnux series general description the bu9002xnux are a high efficiency 1mhz synchronous step-down switching regulator with low current pfm mode. it provides up to 1.5a load current and an input vo ltage range from 4.5v to 5.5v, optimized for various applications with input voltage range up to 5v. bu9002xnux has a mode control pin that allows the user to select forced pwm (pulse width modulation) mode or pfm (pulse frequency modulation) and pwm auto change mode utilized power save operation at l ight load current. features fast transient response automatic pfm/pwm operation. forced pwm operation internal soft start under voltage lockout over current protection thermal shutdown lineup pin configuration(s) applications pol, 1cell li-ion battery for portable applications , usb accessories package(s) w(typ.) x d(typ.) x h(max.) vson008x2030 2.00mm x 3.00mm x 0.60mm typical application circuit(s) pin description(s) part no. output voltage bu90023nux 1.230v bu90028nux 1.175v pin no. symbol function 1 lx inductor connection pin 2 mode forced pwm mode pin 3 pvin power supply input pin 4 vin power supply input pin 5 en enable pin 6 agnd gnd pin 7 pgnd gnd pin 8 fb feedback voltage input pin vson008x2030 (top view) figure 2. pin configuration(s) figure 1. typical application circuit(s) downloaded from: http:///
2/11 d a t a s h e e t bu9002xnux series tsz02201-0f2f0ag00020-1- 2 ? 2012 rohm co., ltd. all rights reserved. 21.jun.2012 rev.001 www.rohm.com tsz22111 15 001 + - y l / l a a / l block diagram(s) description of block(s) the bu9002xnux are a synchronous step-down dc/dc con verter that achieves fast transient response from l ight load to heavy load by hysteretic pwm control system and current c onstant pfm control system. pwm control bu9002xnux operates by hysteretic pwm control. this scheme ensures fast switching, high efficiency, and fast transient response. when the output voltage is below the vref voltage, th e error comparator output is low to high and turnin g on p-channel mosfet until above the vref voltage and minimum on tim e. pfm control at light load the regulator and mode=low, the regulat or operates with reduced switching frequency and im proves the efficiency. during pfm operation, the output voltage slightly hi gher than typical output voltage. figure 4. operation of pfm mode and pwm mode figure 3. block diagram(s) downloaded from: http:/// 3/11 a t a s h e e t bu9002xnux series tsz02201-0f2f0ag00020-1- 2 ? 2012 rohm co., ltd. all rights reserved. 21.jun.2012 rev.001 www.rohm.com tsz22111 15 001 description of operations 1) shutdown if the en input pin set to low (<0.4v), all circuit a re shut down and the regulator is standby mode. do not leave the en pin floating. 2) soft start function the regulator has a soft start circuit that reduces in-rush current at start-up. typical start up times with a 2.2uf output capacito r is 240usec. 3) current limit the bu9002xnux has a current limit circuit that prot ects itself and external components during overload condition. 4) uvlo the bu9002xnux has a under voltage lock out circuit that turn off device when vin>2.05v(typ.) 5) forced pwm mode setting mode pin high (>1.4v) places the regulator in forced pwm. this control provides noise reduction and output stability. do not leave the mode pin floating. 6) tsd the bu9002xnux has a thermal shutdown feature to pro tect the device if the junction temperature exceeds 150 .in thermal shutdown, the driver is disabled. this circuit is only to cut off the ic from thermal runaway, and has not been design to protect or gua rantee the ic. therefore, the user should not plan to activate this circuit with continued operation in mind. absolute maximum ratings (ta=25 ) (*1) when mounted on the specified pcb (55mm x 63mm), deducted by 3.9m w/c when used over ta=25c recommended operating rating(s) parameter symbol rating unit maximum input power supply voltage vin 7 v maximum voltage at en, fb, lx, mode ven, vfb, vlx, vmode 7 v power dissipation pd 0.515 w operating temperature range topr -40 to +85 storage temperature range tstg -55 to +125 junction temperature tjmax +125 parameter symbol rating unit series min. typ. max. input voltage vin 2.3 - 5.5 v downloaded from: http:/// 4/11 a t a s h e e t bu9002xnux series tsz02201-0f2f0ag00020-1- 2 ? 2012 rohm co., ltd. all rights reserved. 21.jun.2012 rev.001 www.rohm.com tsz22111 15 001 electrical characteristic(s) (unless otherwise specified vin=5.0v, ta=25 ) item symbol rating unit condition min. typ. max. switching regulator output voltage accuracy vouta 1.206 1.230 1.254 v bu90023nux mode:h pwm 1.152 1.175 1.199 bu90028nux mode:h pwm soft start soft start time tss 120 240 480 usec frequency control switching frequency fosc 0.8 1.0 2.0 mhz driver pchfet on resistance ronp - 250 400 mohm vin=5.0v nchfet on resistance ronn - 220 350 mohm vin=5.0v control en pin control voltage operation venh 1.4 - vin v non operation venl 0 - 0.4 v mode pin control voltage operation vmodeh 1.4 - vin v forced pwm non operation vmodel 0 - 0.4 v automatic pfm/pwm uvlo protect threshold voltage uvth 1.95 2.05 2.15 v hysteresis uvhy 50 100 150 mv current limit current limit threshold ilimit 2.2 2.5 2.8 a pmos current detect, open loop output discharge output discharge resistance dres 55 110 220 ohm en=0v circuit current operating quiescent current iins 53 75 ua en:h, mode:l, vout=3.6v forced not switching shutdown current shd - 0 1 ua en=0v downloaded from: http:/// 5/11 a t a s h e e t bu9002xnux series tsz02201-0f2f0ag00020-1- 2 ? 2012 rohm co., ltd. all rights reserved. 21.jun.2012 rev.001 www.rohm.com tsz22111 15 001 electrical characteristic curves (reference data) bu90023nux (1.23v output figure 5. start up figure 7. load transient response 400ma to 800ma tr=tf=100ns, mode : low figure 8. load transient response 600ma to 1200ma tr=tf=100ns, mode : low figure 6. shut down vout 50mv/div ac coupled iout 500ma/div vout 1v/div en 2v/div il 500ma/div en 2v/div vout 1v/div vout 50mv/div ac coupled iout 500ma/div downloaded from: http:/// 6/11 a t a s h e e t bu9002xnux series tsz02201-0f2f0ag00020-1- 2 ? 2012 rohm co., ltd. all rights reserved. 21.jun.2012 rev.001 www.rohm.com tsz22111 15 001 electrical characteristic curves (reference data) bu90023nux (1.23v output) continued figure 9. pwm mode operation iout=50ma figure 10. efficiency vs load current vin=5v pwm/pfm auto mode figure 11. load regulation pwm mode il 500ma/div vout 20mv/div ac coupled lx 2v/div vin=5.5 vin=5.0 vin=4.0 downloaded from: http:/// 7/11 a t a s h e e t bu9002xnux series tsz02201-0f2f0ag00020-1- 2 ? 2012 rohm co., ltd. all rights reserved. 21.jun.2012 rev.001 www.rohm.com tsz22111 15 001 electrical characteristic curves (reference data) bu90028nux (1.175v output) figure 12. start up figure 14. load transient response 400ma to 800ma tr=tf=100ns, mode : low figure 15. load transient response 600ma to 1200ma tr=tf=100ns, mode : low figure 13. shut down vout 50mv/div ac coupled iout 500ma/div vout 1v/div en 2v/div il 500ma/div en 2v/div vout 1v/div vout 50mv/div ac coupled iout 500ma/div downloaded from: http:/// 8/11 a t a s h e e t bu9002xnux series tsz02201-0f2f0ag00020-1- 2 ? 2012 rohm co., ltd. all rights reserved. 21.jun.2012 rev.001 www.rohm.com tsz22111 15 001 ?? ( ? ) bu90028nux 1.175v continued vin=5.5 vin=5.0 vin=4.0 figure 16. pwm mode operation iout=50ma figure 17. efficiency vs load current vin=5v pwm/pfm auto mode figure 18. load regulation pwm mode il 500ma/div vout 20mv/div ac coupled lx 2v/div downloaded from: http:/// 9/11 a t a s h e e t bu9002xnux series tsz02201-0f2f0ag00020-1- 2 ? 2012 rohm co., ltd. all rights reserved. 21.jun.2012 rev.001 www.rohm.com tsz22111 15 001 pc board layout the suggested pcb layout for the bu9002xnux are shown in figure. the following guidelines should be used to ensure a proper layout. 1) the input capacitor cin should be connect as clo sely possible to vin pin and gnd pin. 2) from the output voltage to the fb pin line should be as separate as possible. 3) cout and l should be connected as closely as pos sible. the connection of l to the lx pin should be as short as possible. figure 19. pcb layout external parts selection inductor selection the inductance significantly depends on output ripp le current. as shown by following equation, the ripp le current decreases as the inductor and/or switching frequency increase. f: switching frequency l: inductance S i l : inductor current ripple as a minimum requirement, the dc current rating of t he inductor should be equal to the maximum load curr ent plus half of the inductor current ripple as shown by the following e quation. 1) recommended inductor selection iout Q 1.5a dfe252012c type 2.2uh (toko) nr4018t2r2m (taiyo yuden) iout Q 0.6a nr3010t2r2m (taiyo yuden) 2) recommended input capacitor(cin) selection c1608 type 22uf (x5r 6.3v tdk) 3)recommended output capacitor(cout) selection c1608 type 22uf (x5r 6.3v tdk) (vin-vout) vout S i l = l vin f S i l i lpeak = 2 i outmax + downloaded from: http:/// 10/11 a t a s h e e t bu9002xnux series tsz02201-0f2f0ag00020-1- 2 ? 2012 rohm co., ltd. all rights reserved. 21.jun.2012 rev.001 www.rohm.com tsz22111 15 001 caution of use 1) absolute maximum ratings an excess in the absolute maximum rating, such as su pply voltage, temperature range of operating condit ions, etc., can break down the devices, thus making impossible to identify breaking mode, such as a short circuit or an open circuit. if any over rated values will expect to ex ceed the absolute maximum ratings, consider adding circuit protection devices, such as fuses. 2) gnd voltage the potential of gnd pin must be minimum potential in all condition. as an exception, the circuit desi gn allows voltages up to -0.3 v to be applied to the ic pin. 3) thermal design use a thermal design that allows for a sufficient m argin in light of the power dissipation (pd) in actu al operating conditions. 4) inter-pin shorts and mounting errors use caution when positioning the ic for mounting on printed circuit boards. the ic may be damaged if t here is any connection error or if pins are shorted together. 5) actions in strong electromagnetic field use caution when using the ic in the presence of a strong electromagnetic field as doing so may cause the ic to malfunction. 6) mutual impedance power supply and ground wiring should reflect consid eration of the need to lower mutual impedance and m inimize ripple as much as possible (by making wiring as sho rt and thick as possible or rejecting ripple by inc orporating inductance and capacitance). 7) thermal shutdown circuit (tsd circuit) this model ic has a built-in tsd circuit. this circu it is only to cut off the ic from thermal runaway, and has not been design to protect or guarantee the ic. therefore, t he user should not plan to activate this circuit wi th continued operation in mind. 8) regarding input pin of the ic this monolithic ic contains p+ isolation and p subs trate layers between adjacent elements in order to keep them isolated. p-n junctions are formed at the intersection of thes e p layers with the n layers of other elements, cre ating a parasitic diode or transistor. for example, as shown in the f igures below, the relation between each potential i s as follows: when gnd > pin a and gnd > pin b, the p-n junction oper ates as a parasitic diode. when gnd > pin b, the p-n junction operates as a paras itic transistor. parasitic diodes can occur inevitable in the structu re of the ic. the operation of parasitic diodes can result in mutual interference among circuits, operational faults, or physical damage. accordingly, methods by which par asitic diodes operate, such as applying a voltage that is lower t han the gnd (p substrate) voltage to an input pin, should not be used. status of this document the japanese version of this document is formal spe cification. a customer may use this translation ver sion only for a reference to help reading the formal version. if there are any differences in translation version of this document formal version takes priority downloaded from: http:/// 11/11 a t a s h e e t bu9002xnux series tsz02201-0f2f0ag00020-1- 2 ? 2012 rohm co., ltd. all rights reserved. 21.jun.2012 rev.001 www.rohm.com tsz22111 15 001 ordering information b u 9 0 0 2 x n u x tr part number package nux: vson008x2030 packaging and forming specification tr: embossed tape and reel (vson008x2030) physical dimension tape and reel information marking diagram(s)(top view) part no. part number marking bu90023nux u90 023 bu90028nux u90 028 vson008x2030 (top view) part number marking lot number 1pin mark ? order quantity needs to be multiple of the minimum quantity. datasheet d a t a s h e e t notice - ge rev.002 ? 2014 rohm co., ltd. all rights reserved. notice precaution on using rohm products 1. our products are designed and manufac tured for application in ordinary elec tronic equipments (such as av equipment, oa equipment, telecommunication equipment, home electroni c appliances, amusement equipment, etc.). if you intend to use our products in devices requiring ex tremely high reliability (such as medical equipment (note 1) , transport equipment, traffic equipment, aircraft/spacecra ft, nuclear power controllers, fuel c ontrollers, car equipment including car accessories, safety devices, etc.) and whose malfunction or failure may cause loss of human life, bodily injury or serious damage to property (specific applications), please consult with the rohm sale s representative in advance. unless otherwise agreed in writing by rohm in advance, rohm shall not be in any way responsible or liable for any damages, expenses or losses incurred by you or third parties arising from the use of any ro hms products for specific applications. (note1) medical equipment classification of the specific applications japan usa eu china class class class b class class | class 2. rohm designs and manufactures its products subject to strict quality control system. however, semiconductor products can fail or malfunction at a certain rate. please be sure to implement, at your own responsibilities, adequate safety measures including but not limited to fail-safe desi gn against the physical injury, damage to any property, which a failure or malfunction of our products may cause. the following are examples of safety measures: [a] installation of protection circuits or other protective devices to improve system safety [b] installation of redundant circuits to reduce the impact of single or multiple circuit failure 3. our products are designed and manufactured for use under standard conditions and not under any special or extraordinary environments or conditio ns, as exemplified below. accordin gly, rohm shall not be in any way responsible or liable for any damages, expenses or losses arising from the use of an y rohms products under any special or extraordinary environments or conditions. if you intend to use our products under any special or extraordinary environments or conditions (as exemplified below), your independent verification and confirmation of product performance, reliability, etc, prior to use, must be necessary: [a] use of our products in any types of liquid, incl uding water, oils, chemicals, and organic solvents [b] use of our products outdoors or in places where the products are exposed to direct sunlight or dust [c] use of our products in places where the products ar e exposed to sea wind or corrosive gases, including cl 2 , h 2 s, nh 3 , so 2 , and no 2 [d] use of our products in places where the products are exposed to static electricity or electromagnetic waves [e] use of our products in proximity to heat-producing components, plastic cords, or other flammable items [f] sealing or coating our products with resin or other coating materials [g] use of our products without cleaning residue of flux (ev en if you use no-clean type fluxes, cleaning residue of flux is recommended); or washing our products by using water or water-soluble cleaning agents for cleaning residue after soldering [h] use of the products in places subject to dew condensation 4. the products are not subjec t to radiation-proof design. 5. please verify and confirm characteristics of the final or mounted products in using the products. 6. in particular, if a transient load (a large amount of load applied in a short per iod of time, such as pulse. is applied, confirmation of performance characteristics after on-boar d mounting is strongly recomm ended. avoid applying power exceeding normal rated power; exceeding the power rating under steady-state loading c ondition may negatively affect product performance and reliability. 7. de-rate power dissipation (pd) depending on ambient temper ature (ta). when used in seal ed area, confirm the actual ambient temperature. 8. confirm that operation temperat ure is within the specified range described in the product specification. 9. rohm shall not be in any way responsible or liable for fa ilure induced under deviant condi tion from what is defined in this document. precaution for mounting / circuit board design 1. when a highly active halogenous (chlori ne, bromine, etc.) flux is used, the resi due of flux may negatively affect product performance and reliability. 2. in principle, the reflow soldering method must be used; if flow soldering met hod is preferred, please consult with the rohm representative in advance. for details, please refer to rohm mounting specification downloaded from: http:/// datasheet d a t a s h e e t notice - ge rev.002 ? 2014 rohm co., ltd. all rights reserved. precautions regarding application examples and external circuits 1. if change is made to the constant of an external circuit, pl ease allow a sufficient margin considering variations of the characteristics of the products and external components, including transient characteri stics, as well as static characteristics. 2. you agree that application notes, re ference designs, and associated data and in formation contained in this document are presented only as guidance for products use. theref ore, in case you use such information, you are solely responsible for it and you must exercise your own independent verification and judgment in the use of such information contained in this document. rohm shall not be in any way responsible or liable for any damages, expenses or losses incurred by you or third parties arising from the use of such information. precaution for electrostatic this product is electrostatic sensitive product, which may be damaged due to electrostatic discharge. please take proper caution in your manufacturing process and storage so that voltage exceeding t he products maximum rating will not be applied to products. please take special care under dry condit ion (e.g. grounding of human body / equipment / solder iron, isolation from charged objects, se tting of ionizer, friction prevention and temperature / humidity control). precaution for storage / transportation 1. product performance and soldered connections may deteriora te if the products are stor ed in the places where: [a] the products are exposed to sea winds or corros ive gases, including cl2, h2s, nh3, so2, and no2 [b] the temperature or humidity exceeds those recommended by rohm [c] the products are exposed to di rect sunshine or condensation [d] the products are exposed to high electrostatic 2. even under rohm recommended storage c ondition, solderability of products out of recommended storage time period may be degraded. it is strongly recommended to confirm sol derability before using products of which storage time is exceeding the recommended storage time period. 3. store / transport cartons in the co rrect direction, which is indicated on a carton with a symbol. otherwise bent leads may occur due to excessive stress applied when dropping of a carton. 4. use products within the specified time after opening a humidity barrier bag. baking is required before using products of which storage time is exceeding the recommended storage time period. precaution for product label qr code printed on rohm products label is for rohms internal use only. precaution for disposition when disposing products please dispose them proper ly using an authorized industry waste company. precaution for foreign exchange and foreign trade act since our products might fall under cont rolled goods prescribed by the applicable foreign exchange and foreign trade act, please consult with rohm representative in case of export. precaution regarding intellectual property rights 1. all information and data including but not limited to application example contained in this document is for reference only. rohm does not warrant that foregoi ng information or data will not infringe any intellectual property rights or any other rights of any third party regarding such information or data. rohm shall not be in any way responsible or liable for infringement of any intellectual property rights or ot her damages arising from use of such information or data.: 2. no license, expressly or implied, is granted hereby under any intellectual property rights or other rights of rohm or any third parties with respect to the information contained in this document. other precaution 1. this document may not be reprinted or reproduced, in whol e or in part, without prior written consent of rohm. 2. the products may not be disassembled, converted, modified, reproduced or otherwise changed without prior written consent of rohm. 3. in no event shall you use in any wa y whatsoever the products and the related technical information contained in the products or this document for any military purposes, incl uding but not limited to, the development of mass-destruction weapons. 4. the proper names of companies or products described in this document are trademarks or registered trademarks of rohm, its affiliated companies or third parties. downloaded from: http:/// datasheet datasheet notice C we rev.001 ? 2014 rohm co., ltd. all rights reserved. general precaution 1. before you use our pro ducts, you are requested to care fully read this document and fully understand its contents. rohm shall n ot be in an y way responsible or liabl e for fa ilure, malfunction or acci dent arising from the use of a ny rohms products against warning, caution or note contained in this document. 2. all information contained in this docume nt is current as of the issuing date and subj ec t to change without any prior notice. before purchasing or using rohms products, please confirm the la test information with a rohm sale s representative. 3. the information contained in this doc ument is provi ded on an as is basis and rohm does not warrant that all information contained in this document is accurate an d/or error-free. rohm shall not be in an y way responsible or liable for an y damages, expenses or losses incurred b y you or third parties resulting from inaccur acy or errors of or concerning such information. downloaded from: http:/// |
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