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high efficiency 1mhz, 2a, step up regulator EC9208 e - c m o s c o r p . ( ww w . e c m o s . c o m . t w ) p a g e 1 o f 11 4d10n - rev.f 001 general description ec92 08 is a high efficiency, current \ mode control boost dc to dc regulator with an integrated 120m ? r ds(on) n \ channel mosfet. the fixed 1mhz switching frequency and internal compensation reduce external component count and save the pcb space. the build \ in internal soft start circuitry minimizes the inrush current at start \ up. featur e s wide input range:2 .7v ~6v 1mhz switching frequency minimum on time: 100ns typical minimum off time: 100ns typical max output voltage: 6v low r ds(0n ) : 120m rohs compliant and halogen free compact package: sot2 3 - 6 applications cell phone and smart phone pda, pmp, mp3 digital camera package types sot23 - 6 figu r e 1. p ac k age t yp e s of ec92 08
high efficiency 1mhz, 2a, step up regulator EC9208 e - c m o s c o r p . ( ww w . e c m o s . c o m . t w ) p a g e 2 o f 11 4d10n - rev.f 001 pin configurations figu r e 2 pin c o nfigu r ation o f ec9 208 ( t o p v i e w ) pin description pin number pin name description 1 lx inductor node. connect an inductor between in pin and lx pin. 2 gdn gnd 3 fb feedback pin. connect a resistor r1 between vout and fb, and a resistor r2 between fb and gnd to program the output voltage: vout=0.6v*(r1/r2+1) 4 en enable control. high to turn on the part. dont leave it floated. 5 in power input pin. 6 nc
high efficiency 1mhz, 2a, step up regulator EC9208 e - c m o s c o r p . ( ww w . e c m o s . c o m . t w ) p a g e 3 o f 11 4d10n - rev.f 001 orderi n g information function block figu r e 3 f u n c t i o n block diag r am of ec92 08 part number package marking marking information ec 9208nnb3r sot23 - 6 9 2 08f 1. starting with underlined 2, a bar is for production year 2012. the next bar is mark on top of 0 is for year 2013. the next bar is mark on bottom of 0 is for year 2014.the next bar is mark on top of 8 is year for 2015. the naming pattern continues with consecutive characters for later years. 2. f is the week of production. the big character of a~z is for the week of 1~26, and small a~z is for the week of 27~52.
high efficiency 1mhz, 2a, step up regulator EC9208 e - c m o s c o r p . ( ww w . e c m o s . c o m . t w ) p a g e 4 o f 11 4d10n - rev.f 001 absol u te maximum rati n gs en, vdd, lx \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ 7v fb \\\\\\\\\\\\\\\\\\\\\\\\\\ \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ \\\ 3.6v power dissipation, p d @ t a = 25c, sot23 \ 6 \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ 0.6w package thermal resistance (note 2) sot23 \ 6, ja \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ 200c/w sot23 \ 6, jc \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ 130c/w junction temperature range \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ 125c lead temperature (soldering, 10 sec.) \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ 260c storage temperature range \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ \ 65c to 150c recommended operating conditions vdd pin \\\\\\\\\\\\\\\\\\\\\\\\\\ \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ 2 .7 v to 6v fb \\\\\\\\\\\\\\\\\\\\ \\\\\\\\\\\\\\\\\\\\\\\\\\\ \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ 0v to 1v junction temperature range \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ \ 40c to 125c ambient tempe rature range \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ \ 40c to 85c electrical characteristics (v in = 3.3v, v out =5v, i out =100ma, t a = 25c unless otherwise specified) parameters symbol test condition min. typ. max. unit input voltage range v in 2.7 6 v quiescent current i q v fb =0.66v 200 a low side main fet rds(on) 120 m ? main fet current i lim1 3 a switching frequency fsw 0.8 1 1.2 mhz feedback reference v ref 0.588 0.6 0.612 v in uvlo rising v in,uvlo 2.5 v thermal shutdown t sd 150 c
high efficiency 1mhz, 2a, step up regulator EC9208 e - c m o s c o r p . ( ww w . e c m o s . c o m . t w ) p a g e 5 o f 11 4d10n - rev.f 001 typical perf or man ce characteristics
high efficiency 1mhz, 2a, step up regulator EC9208 e - c m o s c o r p . ( ww w . e c m o s . c o m . t w ) p a g e 6 o f 11 4d10n - rev.f 001 typical perf or man ce characteristics(cont.)
high efficiency 1mhz, 2a, step up regulator EC9208 e - c m o s c o r p . ( ww w . e c m o s . c o m . t w ) p a g e 7 o f 11 4d10n - rev.f 001 typical perf or man ce characteristics(cont.)
high efficiency 1mhz, 2a, step up regulator EC9208 e - c m o s c o r p . ( ww w . e c m o s . c o m . t w ) p a g e 8 o f 11 4d10n - rev.f 001 typical application circuit figure 4 . t ypi ca l a p p l i c a t i o n c i r c u i t 1 figure 5 . typical application circuit 2
high efficiency 1mhz, 2a, step up regulator EC9208 e - c m o s c o r p . ( ww w . e c m o s . c o m . t w ) p a g e 9 o f 11 4d10n - rev.f 001 function description because of the high integration in the EC9208 ic, the application circuit based on this regulator ic is rather simple. only input capa citor c in , output capacitor c out , inductor l and feedback resistors (r 1 and r 2 ) need to be selected for the targeted applications spe cifications. feedback resistor dividers r 1 and r 2 : choose r 1 and r 2 to program the proper output voltage. to minimize the power consumption under light loads, it is desirable to choose large resistance values for both r 1 and r 2 . a value of between 10k and 1m is recommended for both resistors. if r 1 =200k is chosen, then r 2 can be calculated to be: output capacitor c out : the output capacitor is selected to handle the output ripple noise requirements. both steady state ripple and transient requirements must be taken into consideration when selecting this capacitor. for the best performance, it is recommended to use x5r or bette r grade ceramic capacitor with 25v rating and more than two pcs 10uf capacitor. input capacitor c in : the ripple current through input capacitor is calculated as: to minimize the potential noise problem, place a typical x5r or better grade ceramic capacitor really close to the vdd and gnd pins. care should be taken to minimize the loop area formed by c in , and vdd/gnd pins. in this case a 22uf low esr ceramic capacitor is recommended. boost inductor l: there are several considerations in choosing this inductor. 1) choose the inductance to provide the desired ripple current. it is suggested to choose the ripple current to be about 40% of the maximum average input current. the inductance is calculated as: where f sw is the switching frequency and i out,max is the maximum load current. the EC9208 regulator ic is quite tolerant of different ripple current amplitude. consequently, the final choice of inductance can be slightly off the calculation value without significantly impacting the performance. 2) the saturation current rating of the inductor must be selected to be greater than the peak inductor current under full load conditi ons. 3) the dcr of the inductor and the core loss at the switching frequency must be low enough to achieve the desired efficiency requirement. it is desirable to choose an inductor with dcr<50mohm to achieve a good overall efficiency. enable operation pulling the en pin low (<0.4v) will shut down the device. during the shut down mode, the EC9208 shut down current drops to lower than 1ua, driving the en pin high (>2.0v) will turn on the ic again. diode selection schottky diode is a good choice for high efficiency operation because of its low forward voltage drop and fast reverse recovery. the current rating of the diode must meet following:
high efficiency 1mhz, 2a, step up regulator EC9208 e - c m o s c o r p . ( ww w . e c m o s . c o m . t w ) p a g e 10 o f 11 4d10n - rev.f 001 application information the schottky diode reverse breakdown voltage should be larger than the output voltage. layout design: the layout design of EC9208 regulator is relatively simple. for the best efficiency and minimum noise problems, we should place the following components close to the ic: c in , l, r 1 and r 2 1) it is desirable to maximize the pcb copper area connecting to gnd pin to achieve the best thermal and noise performance. if the board space allowed, a ground plane is highly desirable. 2) c in must be close to pins in and gnd. the loop area formed by c in and gnd must be minimized. 3) the pcb copper area associated with lx pin must be minimized to avoid the potential noise problem. 4) the components r 1 and r 2 , and the trace connecting to the fb pin must not be adjacent to the lx net on the pcb layout to avoid the noise problem. 5) if the system chip interfacing with the en pin has a high impedance state at shutdown mode and the in pin is connected directly to a power source such as a li \ ion battery, it is desirable to add a pull down 1mohm resistor between the en and gnd pins to prevent the noise from falsely turning on the regulator at shutdown mode.
high efficiency 1mhz, 2a, step up regulator EC9208 e - c m o s c o r p . ( ww w . e c m o s . c o m . t w ) p a g e 11 o f 11 4d10n - rev.f 001 package information sot23 - 6 p ack a ge out l ine dimensions

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