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MP2136 2.5v to 6v input, 2mhz, 1a synchronous step -down converter MP2136 rev. 0.9 www.monolithicpower.com 1 8/23/2010 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2010 mps. all rights reserved. the future of analog ic technology description the MP2136 is a 2mhz constant frequency, current mode, pwm step-down converter with integrated main switch and synchronous rectifier that is ideal for powering portable equipment that runs from a single li-ion or li- polymer battery. the MP2136 can supply up to 1a load current from a 2.5v to 6v input voltage. the output voltage can be as low as 0.6v. additional features include <1a shutdown current, internal soft-start, cycle-by-cycle over current protection, short circuit protection, and thermal shutdown. the MP2136 is available in a 6-pin, qfn6 2mm2mm package. features ? 2mhz constant switching frequency ? 1a available load current ? 2.5v 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 ? <1a shutdown current ? internal soft-start ? space-saving 6-pin, qfn6 2mm2mm package applications ? cellular phones ? microprocessors and dsp core supplies ? pdas and smart phones ? mp3 and portable media players ? digital still and video cameras ? portable instruments ?mps? and ?the future of analog ic technology? are registered trademarks of monolithic power systems, inc. typical application vin in en nc gnd fb sw vout en off on 2.5v - 6v 1.2v/1 a c2 10uf r2 300k 1% r1 300k 1% l1 1.2uh u1 MP2136eg 3 2 1 5 6 4 c1 4.7uf efficiency vs. output current l=2.2uh vo=1.2v 0 10 20 30 40 50 60 70 80 90 100 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 vin=3.3v vin=5v vin=2.5v vin=6v efficiency (%) output current (a)
MP2136 ? 2.5v to 6v input, 2mhz, 1a synchronous step-down converter MP2136 rev. 0.9 www.monolithicpower.com 2 8/23/2010 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2010 mps. all rights reserved. ordering information part number* package top marking free air temperature( t a ) MP2136eg qfn6 (2mmx2mm) 6q ? 20c to +85c * for tape & reel, add suffix ?z (eg. MP2136eg?z). for rohs compliant packaging, add suffix ?lf (eg. MP2136eg?lf?z) package reference top view nc en vin 1 2 3 fb gnd sw 6 5 4 absolute maxi mum ratings (1) in to gnd .................................. ? 0.3v to +6.5v sw to gnd .......................... ? 0.3v to v in + 0.3v fb, en to gnd ............................. ? 0.3v to +6.5v continuous power dissipation. (t a = +25c) (2) qfn6 (2mmx2mm) .................................... 2.5w junction temperature ...............................150c lead temperature ....................................260c storage temperature............... ? 65c to +150c recommended operating conditions (3) supply voltage v in .............................2.5v to 6v output voltage v out ...........................0.6v to 6v operating junct.temp. (t j )...... ? 20c to +125c thermal resistance (4) ja jc qfn6 (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), the junction-to- ambient 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 powe r dissipation will cause excessive die 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.
MP2136 ? 2.5v to 6v input, 2mhz, 1a synchronous step-down converter MP2136 rev. 0.9 www.monolithicpower.com 3 8/23/2010 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2010 mps. all rights reserved. electrical characteristics (5) v in = v en = 3.6v, t a = +25 c, unless otherwise noted. parameters condition min typ max units supply current v en = v in , v fb = 0.65v 350 a shutdown current v en = 0v, v in = 6v 0.01 1 a in under voltage lockout threshold rising edge 1.8 2.1 2.3 v in under voltage lockout hysteresis 250 mv t a = +25c 0.582 0.594 0.606 v regulated fb voltage ?40c t a +85c 0.576 0.594 0.612 v fb input bias current v fb = 0.65v -50 50 na pfet current limit duty=100% 1.5 a pfet on-resistance i sw = 100ma 200 m ? nfet on-resistance i sw = ?100ma 150 m ? sw leakage current v en = 0v; v in = 6v v sw = 0v or 6v ?1 1 a en high threshold ?40c t a +85c 1.6 v en low threshold ?40c t a +85c 0.4 v internal soft-start time 150 s oscillator frequency 2 mhz 150 c thermal shutdown threshold hysteresis=20c 20 c note: 5) production test at +25c. specifications over the temperature range are guaranteed by design and characterization.
MP2136 ? 2.5v to 6v input, 2mhz, 1a synchronous step-down converter MP2136 rev. 0.9 www.monolithicpower.com 4 8/23/2010 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2010 mps. all rights reserved. typical performanc e characteristics v out =1.2v, l=1.2uh, c2=10uf, t a =25c, unless otherwise noted. v en 2v/div. v out 500mv/div. v sw 2v/div. i inductor 500ma/div. v en 2v/div. v out 500mv/div. v sw 5v/div. i inductor 500ma/div. v en 2v/div. v out 500mv/div. v sw 5v/div. i inductor 1a/div. v en 2v/div. v out 500mv/div. v sw 2v/div. i inductor 500ma/div. v en 2v/div. v out 500mv/div. v sw 2v/div. i inductor 1a/div. v out /ac 10mv/div. v sw 2v/div. i inductor 500ma/div. v out /ac 10mv/div. v sw 5v/div. i inductor 500ma/div. 40us/div. 40us/div. 40us/div. 40us/div. 200ns/div. 200ns/div. steady state operation vin=2.5v, vo=1.2v, io=1a steady state operation vin=6v, vo=1.2v, io=0a start-up through enable vin=2.5v, vo=1.2v, io=0a start-up through enable vin=2.5v, vo=1.2v, io=1a start-up through en vin=6v, vo=1.2v, io=0a start-up through en vin=6v, vo=1.2v, io=1a v out /ac 10mv/div. v sw 2v/div. i inductor 500ma/div. v out /ac 10mv/div. v sw 5v/div. i inductor 500ma/div. 200ns/div. 200ns/div. steady state operation vin=2.5v, vo=1.2v, io=0a steady state operation vin=6v, vo=1.2v, io=1a 2s/div. power-down through en vin=2.5v , vo=1.2v, io=0a
MP2136 ? 2.5v to 6v input, 2mhz, 1a synchronous step-down converter MP2136 rev. 0.9 www.monolithicpower.com 5 8/23/2010 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2010 mps. all rights reserved. typical performanc e characteristics (continued) v out =1.2v, l=1.2uh, c2=10uf, t a =25c, unless otherwise noted. 1.7 1.75 1.8 1.85 1.9 1.95 2 2.05 2.1 -40 -25 -10 5 20 35 50 65 80 95 110125 1.190 1.192 1.194 1.196 1.198 1.200 1.202 1.204 1.206 1.208 1.210 0 0.10.20.30.40.50.60.70.80.9 1 vin=3.3v vin=5v 0 0.2 0.4 0.6 0.8 1 1.2 1.4 2.533.544.555.56 rising falling
MP2136 ? 2.5v to 6v input, 2mhz, 1a synchronous step-down converter MP2136 rev. 0.9 www.monolithicpower.com 6 8/23/2010 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2010 mps. all rights reserved. pin functions pin # name description 1 nc no connection. leave pin1 disconnection. 2 en regulator enable control input. drive en above 1.6v to turn on the part. drive en below 0.4v to turn it off. 3 in supply input. bypass to gnd with a 4.7 f or bigger value ceramic capacitor. 4 sw power switch output. inductor connection to drains of the internal pfet and nfet switches. 5 gnd, exposed pad ground. connect exposed pad to ground plane for optimal thermal performance. 6 fb feedback input. connect fb to the center poi nt of the external resistor divider. the regulated feedback voltage is 0.6v.
MP2136 ? 2.5v to 6v input, 2mhz, 1a synchronous step-down converter MP2136 rev. 0.9 www.monolithicpower.com 7 8/23/2010 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2010 mps. all rights reserved. functional block diagram i sw i sw eao 0.6v 0.6v 17pf 0.5pf 1.2meg in en fb gnd dl dl dh osc pwm pgate low side gate drive main switch pch high side gate drive pwm control logic synchronous rectifier nch sw slope comp 2mhz oscillator 150us internal ss bias &voltage reference slope comp figure 1? functional block diagram
MP2136 ? 2.5v to 6v input, 2mhz, 1a synchronous step-down converter MP2136 rev. 0.9 www.monolithicpower.com 8 8/23/2010 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2010 mps. all rights reserved. functional description MP2136 is a 2mhz 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 an external schottky diode. it is ideal for powering portable equipment that runs from a single li-lon or li-polymer battery. the MP2136 can achieve 100% duty cycle. the duty cycle d of a step-down converter is defined as: out on osc in v dt f 100% 100% v = where, ton: main switch on time fosc: switching frequency (2mhz) vout: output voltage vin: input voltage peak current mode pwm control slope compensated current mode pwm control provides stable switching and cycle-by-cycle current limit for superior load and line response and protection of the internal main switch and synchronous rectifier. the MP2136 switches at a constant frequency (2mhz) and regulates the output voltage. during each cycle the pwm comparator modulates the power transferred to the load by changing the inductor peak current based on the feedback error voltage. during normal operation, the main switch is turned on for a certain time to ramp the inductor current at each rising edge of the internal oscillator, and switched off when the peak inductor current is above the error voltage. when the main switch is off, the synchronous rectifier will be turned on immediately and stay on until the next cycle starts. dropout operation the MP2136 allows the main switch to remain on for more than one switching cycle and increases the duty cycle while the input voltage is dropping close to the output voltage. when the duty cycle reaches 100%, the main switch is held on continuously to deliver current to the output up to the pfet current limit. the output voltage then is the input voltage minus the voltage drop across the main switch and the inductor. short circuit protection the MP2136 has short circuit protection. when the output is shorted to ground, the oscillator frequency is reduced to prevent the inductor current from increasing beyond the pfet current limit. the pfet current limit is also reduced to lower the short-circuit current. the frequency and current limit will return to the normal values once the short circuit condition is removed and the feedback voltage reaches 0.6v. maximum load current the MP2136 can operate down to 2.5v input voltage, however the maximum load current decreases at lower input due to large ir drop on 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.
MP2136 ? 2.5v to 6v input, 2mhz, 1a synchronous step-down converter MP2136 rev. 0.9 www.monolithicpower.com 9 8/23/2010 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2010 mps. all rights reserved. application information output voltage setting the external resistor divider sets the output voltage. the feedback resistor r1 also sets the feedback loop bandwidth with the internal compensation capacitor. choose r1 around 300k ? for optimal transient response. r2 is then given by: 1 v 6 . 0 v 1 r 2 r out ? = table 1?resistor selection vs. output voltage setting v out r1 r2 1.2v 300k ? (1%) 300k ? (1%) 1.5v 300k ? (1%) 200k ? (1%) 1.8v 300k ? (1%) 150k ? (1%) 2.5v 300k ? (1%) 95.3k ? (1%) inductor selection a 0.68h to 10h inductor with dc current rating at least 25% higher than the maximum load current is recommended for most applications. for best efficiency, the inductor dc resistance shall be <200m ? . for most designs, the inductance value can be derived from the following equation: () osc l in out in out f i v v v v l ? ? = where ? i l is the inductor ripple current. choose inductor ripple current approximately 30% of the maximum load current, 1a. the maximum inductor peak current is: 2 i i i l load ) max ( l ? + = under light load conditions below 100ma, larger inductance is recommended for improved efficiency. input capacitor selection the input capacitor reduces the surge current drawn from the input and switching noise from the device. the input capacitor impedance at the switching frequency shall be less than input source impedance to prevent high frequency switching current passing to the input. ceramic capacitors with x5r or x7r dielectrics are highly recommended because of their low esr and small temperature coefficients. the input capacitor absorbs the input switching current, so it requires an adequate ripple current rating. the rms current through the input capacitor can be estimated by: out out cin load in in vv ii (1 ) vv = ? the worse case condition occurs at v in =2v out where: load cin i i 2 = for simplification, choose the input capacitor whose rms current rating greater than half of the maximum load current. for most applications, a 4.7f capacitor is sufficient. output capacitor selection the output capacitor keeps output voltage ripple small and ensures regulation loop stable. the output capacitor impedance shall be low at the switching frequency. ceramic capacitors with x5r or x7r dielectrics are recommended. the output ripple ? v out is approximately: ( ) ? ? ? ? ? ? ? ? + ? ? 3 c f 8 1 esr l f v v v v v osc osc in out in out out for most applications, a 10uf capacitor is sufficient.
MP2136 ? 2.5v to 6v input, 2mhz, 1a synchronous step-down converter MP2136 rev. 0.9 www.monolithicpower.com 10 8/23/2010 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2010 mps. all rights reserved. pcb layout guide pcb layout is very important to achieve stable operation. it is highly recommended to duplicate evb layout for optimum performance. if change is necessary, please follow these guidelines and take figure 2 for reference. 1) keep the path of switching current short and minimize the loop area formed by input cap, high-side mosfet and low-side mosfet. 2) bypass ceramic capacitors are suggested to be put close to the v in pin. 2) ensure all feedback connections are short and direct. place the feedback resistors as close to the chip as possible. 4) route sw away from sensitive analog areas such as fb. 5) connect in, sw, and especially gnd respectively to a large copper area to cool the chip to improve thermal performance and long-term reliability. top layer bottom layer figure 2?MP2136 suggested layout
MP2136 ? 2.5v to 6v input, 2mhz, 1a synchronous step-down converter notice: the information in this document is subject to change wi thout notice. users should warra nt and guarantee that third party intellectual property rights are not infringed upon w hen integrating mps products into any application. mps will not assume any legal responsibility for any said applications. MP2136 rev. 0.9 www.monolithicpower.com 11 8/23/2010 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2010 mps. all rights reserved. package information qfn6 (2mmx2mm) side view top view 1 6 4 3 bottom view 1.90 2.10 0.65 0.85 1.90 2.10 1.25 1.45 0.65 bsc 0.20 0.30 0.80 1.00 0.00 0.05 0.20 ref pin 1 id marking 0.70 0.65 0.25 recommended land pattern 1.90 pin 1 id see detail a 1.40 0.70 pin 1 id option a 0.30x45o typ. pin 1 id option b r0.20 typ. detail a 0.30 0.40 pin 1 id index area

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