? semiconductor components industries, llc, 2002 june, 2002 rev. 0 1 publication order number: ncp1421/d ncp1421 product preview 500 ma sync-rect pfm step-up dc-dc converter with true-cutoff and ring-killer ncp1421 is a monolithic micropower high frequency stepup switching converter ic specially designed for battery operated handheld electronic products up to 500 ma loading. it integrates syncrect for improving efficiency as well as eliminating the external schottky diode. high switching frequency (up to 800 khz) allows low profile inductor and output capacitor being used. when the ic is disabled, internal conduction path from lx or bat to out is blocked, out pin is isolated from the battery. this achieves truecutoff. ringkiller is also integrated to eliminate the high frequency ringing in discontinuous conduction mode. lowbattery detector, logiccontrolled shutdown, cyclebycycle current limit and thermal shutdown provide valueadded features for various battery operated application. with all these functions on, the quiescent supply current is only 15 a. this device is available in compact micro8 package. features ? high efficiency: 94% for 3.3 v output at 200 ma from 2.0 v input ? 84% for 3.3 v output at 500 ma from 2.5 v input ? high switching frequency, up to 800 khz (not hitting current limit) ? truecutoff: out pin is isolated from bat or lx pin during ic disabled ? high accuracy reference output, 1.18 v 0.6% @ 25 c, can supply 2.5 ma when 3.0 v vout > 3.3 v ? low quiescent current of 15 a ? ringkiller for discontinuous conduction mode ? 1.0 v startup at no load guaranteed ? output voltage from 1.5 v to 5.0 v adjustable ? lowbattery detector ? logiccontrolled shutdown ? thermal shutdown ? 1.5 a cyclebycycle current limit ? open drain lowbattery detector output ? output current up to 500 ma typical applications ? personal digital assistants (pda) ? handheld digital audio product ? camcorders and digital still camera ? handheld instrument ? conversion from one nih or nicd or one lithiumion cells to 3.3 v/5.0 v this document contains information on a product under development. on semiconductor reserves the right to change or discontinue this product without notice. micro8 dm suffix case 846a 1 8 pin connections fb out lbi/en lbo ref lx gnd bat device package shipping ordering information ncp1421dm micro8 4000 t ape & reel 18 2 3 4 7 6 5 http://onsemi.com marking diagram a = assembly location wl, l = wafer lot yy, y = year ww, w = work week tbd (top view)
ncp1421 http://onsemi.com 2 figure 1. simplified block diagram + - pfm control logic driver true cutoff driver 8 7 out lx vref 5 bat gnd 6 - + 1 fb 2 lbi/en 3 lbo 4 ref chip enable figure 2. typical operating circuit lbi/en fb lbo ref bat gnd lx out 1 2 3 4 8 7 6 5 ncp1421 r lb2 200 k r lb1 low battery sense input shutdown open drain input low battery open drain output 300 nf 350 k 20 f + output 1.5 to 5.5 v i out typical up to 500 ma at 3.3 v output and 2.5 v input 20 f input 1 v to v out 10 h
ncp1421 http://onsemi.com 3 chip enable figure 3. detailed block diagram _zcur _mson _cen _pfm _tsdon _mainsw2on _mainswofd _synsw2on _synswofd _v refok control logic 20 mv + - pfm voltage reference ref 4 lbi/en 2 + - fb 1 + - zlc + true cutoff control v dd gnd v dd gnd + - + gnd r sense gnd sensefet m1 v dd m3 bat 5 lx 7 out 8 v bat 6 gnd v out lbo 3 _ilim pin function descriptions pin symbol description 1 fb output voltage feedback input. 2 lbi/en lowbattery detector input and ic enable. 3 lbo opendrain lowbattery detector output. output is low when vlbi is < 1.180 v. lbo is high impedance shutdown. 4 ref 1.180 v reference voltage output, bypass with 150 nf capacitor if this pin is not loaded, bypass with 1.0 f if this pin is loaded up to 2.5 ma @ vout = 3.3 v. 5 bat battery input connection for internal ringkiller. 6 gnd ground. 7 lx nchannel and pchannel power mosfet drain connection. 8 out power output. out also provides bootstrap power to the device.
ncp1421 http://onsemi.com 4 maximum ratings (t c = 25 c unless otherwise noted.) rating symbol value unit power supply (pin 8) vout 0.3, 5.0 v input/output pins pin 15, pin 7 v io 0.3, 5.0 v thermal characteristics micro8 plastic package thermal resistance junctiontoair p d r q ja 520 240 mw c/w operating junction temperature range t j 40 to +150 c operating ambient temperature range t a 40 to +85 c storage temperature range t stg 55 to +150 c electrical characteristics (v out = 3.3 v, t a = 25 c for typical value, 40 c t a = 85 c for min/max values unless otherwise noted.) characteristic symbol min typ max unit operating v oltage v in 1.0 5.0 v output voltage range v out 1.5 vin v reference voltage v ref 1.173 1.180 1.187 v reference voltage temperature coef ficient tc vref 0.03 mv/ c reference voltage load current (v out = 3.3 v, v ref = v ref _nl 1.5% c ref = 1.0 f) (note 5 ) i ref 2.5 ma reference voltage load regulation (v out = 3.3 v, i load = 0 to 100 a, c ref = 1.0 f) v ref_load 0.05 1.0 mv reference voltage line regulation (v out from 1.5 v to 5.0 v, c ref = 1.0 f) v ref_line 0.05 1.0 mv/v fb, lbi input threshold (i load = 0 ma) v fb 1.168 1.180 1.192 v internal nfet onresistance r ds(on)_n 0.3 w internal pfet onresistance r ds(on)_p 0.3 w lx switch current limit (nfet) i lim 1.5 a operating current into out (v fb = 1.4 v, v out = 3.3 v) i q 15 a lx switch max. ontime (v fb = 1.0 v, v out = 3.3 v) t on 0.66 1.06 1.59 s lx switch min. offtime (v fb = 1.0 v, v out = 3.3 v) t off 0.19 s fb input current i fb 1.0 na truecutoff current into bat (lbi/en = gnd, v out = 0, v in = 3.3 v, lx = 3.3 v) i bat 50 na bat to lx resistance (v fb = 1.4 v, v out = 3.3 v) r bat_lx 100 w lbi/en input current i lbi 1.5 8.0 na lbo low output voltage (v lbi = 0, i sink = 1.0 ma) v lbo_l 0.2 v soft start time t ss tbd ms lbi/en pin shutdown threshold v shdn 0.55 0.6 0.65 v 1. this device contains esd protection and exceeds the following tests: human body model (hbm) 2.0 kv per jedec standard: jesd22a114. machine model (mm) 200 v per jedec standard: jesd22a115. 2. the maximum package power dissipation limit must not be exceeded. p d t j(max) t a r ja 3. latchup current maximum rating: 150 ma per jedec standard: jesd78. 4. moisture sensitivity level: msl 1 per ipc/jedec standard: jstd020a. 5. loading capability decreases with vout.
ncp1421 http://onsemi.com 5 package dimensions micro8 dm suffix case 846a02 issue e s b m 0.08 (0.003) a s t dim min max min max inches millimeters a 2.90 3.10 0.114 0.122 b 2.90 3.10 0.114 0.122 c --- 1.10 --- 0.043 d 0.25 0.40 0.010 0.016 g 0.65 bsc 0.026 bsc h 0.05 0.15 0.002 0.006 j 0.13 0.23 0.005 0.009 k 4.75 5.05 0.187 0.199 l 0.40 0.70 0.016 0.028 notes: 1. dimensioning and tolerancing per ansi y14.5m, 1982. 2. controlling dimension: millimeter. 3. dimension a does not include mold flash, protrusions or gate burrs. mold flash, protrusions or gate burrs shall not exceed 0.15 (0.006) per side. 4. dimension b does not include interlead flash or protrusion. interlead flash or protrusion shall not exceed 0.25 (0.010) per side. b a d k g pin 1 id 8 pl 0.038 (0.0015) t seating plane c h j l
ncp1421 http://onsemi.com 6 notes
ncp1421 http://onsemi.com 7 notes
ncp1421 http://onsemi.com 8 on semiconductor and are registered trademarks of semiconductor components industries, llc (scillc). scillc reserves the right to mak e changes without further notice to any products herein. scillc makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does scillc assume any liability arising out of the application or use of any product or circuit, and s pecifically disclaims any and all liability, including without limitation special, consequential or incidental damages. atypicalo parameters which may be provid ed in scillc data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. all operating parameters, including atypicalso must be validated for each customer application by customer's technical experts. scillc does not convey any license under its patent rights nor the rights of others. scillc products are not designed, intended, or authorized for use as components in systems intended for surgical implant into t he body, or other applications intended to support or sustain life, or for any other application in which the failure of the scillc product could create a sit uation where personal injury or death may occur. should buyer purchase or use scillc products for any such unintended or unauthorized application, buyer shall indem nify and hold scillc and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized u se, even if such claim alleges that scillc was negligent regarding the design or manufacture of the part. scillc is an equal opportunity/affirmative action employ er. publication ordering information japan : on semiconductor, japan customer focus center 4321 nishigotanda, shinagawaku, tokyo, japan 1410031 phone : 81357402700 email : r14525@onsemi.com on semiconductor website : http://onsemi.com for additional information, please contact your local sales representative. ncp1421/d literature fulfillment : literature distribution center for on semiconductor p.o. box 5163, denver, colorado 80217 usa phone : 3036752175 or 8003443860 toll free usa/canada fax : 3036752176 or 8003443867 toll free usa/canada email : onlit@hibbertco.com n. american technical support : 8002829855 toll free usa/canada
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