MPQ2128 2.5 v-to - 6v input, 3 mhz, 1 a sy nchronous , step - down converter available in aec - q100 MPQ2128 rev . 1.1 www.monolithicpower.com 1 4/1/2013 mps proprietary information. patent protected. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. ` description the MPQ2128 is a 3 mhz , constant - frequency, current - mode, pwm , step - down converter . it has an integrated main switch and synchronous rectifier that make it ideal for low - voltage conversions. the MPQ2128 can supply up to 1 a load current from a 2 .5 v - to - 6v input voltage. the output voltage can go as low as 0.6v. additional features include <1 a shutdown current, internal soft - start, cycle - by - cycle over - current protection, short - circuit protection, and thermal shutdown . the MPQ2128 is available in a 2mm2mm 8 - pin qfn package. features ? meets automotive requirements ? high ly efficien t : up to 95% ? 3 mhz constant - switching frequency ? 1 a available load current ? 2.5 v - to - 6v input voltage range ? output voltage as low as 0.6v ? current - mode control ? cycle - by - cycle over - current protection ? short - circuit protection ? thermal shutdown ? < 1 a shutdown current ? internal s oft - start ? qfn8 ( 2mm 2mm ) p ackage ? aec - q100 qualified applications ? industrial/ automotive all mps parts are lead - free and adhere to the rohs directive. for mps green status, please visit mps website under products, quality assurance page. ?mps? and ?the fu ture of analog ic technology? are r egistered t rademarks of monolithic power systems, inc. typical application
MPQ2128 ? 3mh z, 1a , s ynchronous , step - down converter MPQ2128 rev . 1.1 www.monolithicpower.com 2 4/1/2013 mps proprietary information. patent protected. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. ordering information part number* package top marking MPQ2128dg qfn8 (2mm 2mm) ay MPQ2128dg - aec 1 * qfn8 (2mm 2mm) ay * for tape & reel, add suffix ? z (eg. MPQ2128 dg - z). for rohs compliant packaging, add suffix ? lf (e . g. MPQ2128dg - lf ? z) package reference qfn8 absolute maximum rat ings (1) in to gnd .................................. ? 0.3v to +6 .5 v sw to gnd .......................... ? 0.3v to v in + 0.3v fb , en to gnd ............................. ? 0.3v to +6.5v continuous p ower dissipation . (t a = +25 c) (2) qfn8 (2mm 2mm) .................................... 2.5w junction temperature .............................. 150c lead temperature ................................... 260c storage temperature .............. ? 65c to + 150c recommended operating conditions (3 ) supply voltage v in ............................ 2.5 v to 6 v output voltage v out .......................... 0.6 v to 6 v operating junctio n temp . ....... ? 40c to +12 5c thermal resistance ( 4 ) ja jc q fn8 (2mmx2mm) ................. 50 ...... 12 ... c/w notes: 1) exceeding these ratings may damage the device. 2) the maximum allowable power dissipation is a function of the maximum junction temperature t j (max), t he junction - to - ambie nt thermal resistance ja , and the ambient temperature t a . the maximum allowable continuous power dissipation at any ambient temperature is calculated by p d (max) = (t j (max) - t a )/ ja . exceeding the maximum allowable power dissipation will cause excessive d ie temperature, and the regulator will go into thermal shutdown. internal thermal shutdown circuitry protects the device from permanent damage. 3) the device is not guaranteed to function outside of its operating conditions. 4) measured on jesd51 - 7, 4 - layer pcb.
MPQ2128 ? 3mh z, 1a , s ynchronous , step - down converter MPQ2128 rev . 1.1 www.monolithicpower.com 3 4/1/2013 mps proprietary information. patent protected. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. electrical character istics (5 ) v in = v en = 3.6 v, t j = - 40 c to 125 c , unless otherwise noted. typical values are at tj = 25 c. parameters condition min typ max units supply current v en = v in , v fb = 0.65v 350 750 a shutdown current v en = 0v, v in = 6v 0.01 1 .2 a in under v oltage lockout threshold rising edge 1. 75 2.1 2.3 v in under v oltage lockout hysteresis 2 50 mv regulated fb voltage t j = +25c 0. 58 2 0. 594 0. 6 06 v ? 40c t j 125 c 0. 5 7 4 0. 594 0. 61 4 v fb input bias current v fb = 0.6 5v - 20 0 20 0 na pfet current limit duty cycle 40% tj = 25 c 1. 8 a - 40c t j 125c 1. 2 p fet on - resistance i sw = 1 00ma 200 m ? n fet on - resistance i sw = ? 1 00ma 150 m ? sw leakage current v en = 0v; v in = 6v v sw = 0v or 6v ? 3 3 a en high threshold ? 40c t j 125 c 1.6 v en low threshold ? 40c t j 125 c 0.4 v internal soft - start time 100 s oscillator frequency 2. 2 2.8 3. 4 mhz thermal shutdown threshold hysteresis=20c 150 c note: 5) production te st at +25c. specifications over the temperature range are guaranteed by design and characterization.
MPQ2128 ? 3mh z, 1a , s ynchronous , step - down converter MPQ2128 rev . 1.1 www.monolithicpower.com 4 4/1/2013 mps proprietary information. patent protected. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. typical performance characteristics v in =6v, v out =1.8v, l=1.2 h, c2=10 f, t a =25 c, unless otherwise noted.
MPQ2128 ? 3mh z, 1a , s ynchronous , step - down converter MPQ2128 rev . 1.1 www.monolithicpower.com 5 4/1/2013 mps proprietary information. patent protected. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. pin functions qfn pin # name description 8 e n enable. drive en above 1.6v to turn on the part. drive en below 0.4v to turn it off. 2,4 gnd ground. 5,6 sw power switch output. connect an inductor to the drain s of the internal pfet and nfet switches. 3 in supply. bypass to gnd with a 4.7f ceramic capacitor. 1 fb feedback. connect to the tap of the external resistor divider. the regulated feedback voltage is 0.6v. exposed pad block diagram figure 1 : functional block diagram
MPQ2128 ? 3mh z, 1a , s ynchronous , step - down converter MPQ2128 rev . 1.1 www.monolithicpower.com 6 4/1/2013 mps proprietary information. patent protected. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. functional description MPQ2128 is a 3mhz , constant frequency, current - mode, pwm , step - down converter. the device integrates both a main switch and a synchronous rectifier, which provides high efficiency and eliminates the need for an external schottky diode. it is ideal for pow ering portable equipment that runs from a single li - lon or li - polymer battery. the MPQ2128 can achieve 100% duty cycle. the duty cycle , d , of the step - down converter is defined as: out on osc in v d t f 100% 100% v = where, on : main switch on time f osc : switching frequency (3mhz) v out : output voltage v in : input voltage peak - current ? mode pwm control slope - compensated , current - mode , pwm control provides stable switching and cycle - by - cycle current limit ing for superior load an d line response , and protects the internal main switch and synchronous rectifier. the MPQ2128 switches at a constant frequency (3mhz) and regulates the output voltage. during each cycle the pwm comparator modulates the power transferred to the load by chan ging the inductor peak current based on the feedback error voltage. during normal operation, the main switch turn s on to ramp - up the inductor current with each rising edge of the internal oscillator, and switche s off when the peak inductor current rises a bove the error voltage. when the main switch is off, the synchronous rectifier turn s on immediately and remains on until the next cycle starts. dropout operation the MPQ2128 allows the main switch to remain on for more than one switching cycle and increase s the duty cycle while the input voltage drop s down to the output voltage. when the duty cycle reaches 100%, the main switch is held on to deliver current to the output up to the pfet current limit. the output voltage is then the difference between the input voltage and the voltage drop across the main switch and the inductor. short - circuit protection the MPQ2128 has short - circuit protection. when the output is shorted to ground, the oscillator frequency reduce s to prevent the inductor current from incre asing beyond the pfet current limit. the pfet current limit also drops to lower the short - circuit current. the frequency and current limit return to the ir normal values once the short circuit condition is removed and the feedback voltage reaches 0.6v. maxi mum load current the MPQ2128 can operate at an input voltage as low as 2.5 v . however the maximum load current decreases with the lower input due to a large voltage drop across the main switch and synchronous rectifier. the slope compensation signal reduces the peak inductor current as a function of the duty cycle to prevent sub - harmonic oscillations at duty cycles greater than 50%. conversely the current limit increases as the duty cycle decreases.
MPQ2128 ? 3mh z, 1a , s ynchronous , step - down converter notice: the information in this document is subject to change without notice. users should warrant and guarantee that third party intellectual property rights are not infringed upon when integrating mps products into any application. mps will not assume any legal responsibility for any said applications. MPQ2128 rev . 1.1 www.monolithicpower.com 7 4/1/2013 mps proprietary information. patent protected. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserv ed. package information q fn8 (2 mm 2 mm)
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