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mp2127 2.7-6v input, 2a, 1.2mhz synchronous step -down converter mp2127 rev. 0.91 www.monolithicpower.com 1 4/27/2010 mps proprietary information. unaut horized photocopy and d uplication prohibited. ? 2010 mps. all rights reserved. the future of analog ic technology description the mp2127 is a fully integrated, internally compensated 1.2mhz fixed frequency pwm step-down converter. it is ideal for powering portable equipment that runs from a single cell lithium-ion (li+) battery, with an input range from 2.7v to 6v. the mp2127 can provide up to 2a of load current with output voltage as low as 0.8v. it can also operate at 100% duty cycle for low dropout applications. with peak current mode control and internal compensation, the mp2127 is stable with ceramic capacitors and small inductors. fault condition protection includes cycle-by-cycle current limiting and thermal shutdown. mp2127 is available in the small 6-pin 3mmx3mm qfn package. features ? output adjustable from 0.8v to vin ? up to 95% efficiency ? 100% duty cycle for low dropout applications ? power good indicator output ? 1.2mhz fixed switching frequency ? stable with low esr output ceramic capacitors ? thermal shutdown ? cycle-by-cycle over current protection ? short circuit protection ? 2.7v-6v input operation range ? available in 6-pin 3x3mm qfn applications ? smart phones, pda?s ? dvd+/-rw drives ? digital cameras ? portable instruments ?mps? and ?the future of analog ic technology? are trademarks of monolithic power systems, inc. typical application mp2127 pvin vin gnd pgood sw fb 1 2 3 6 4 5 c1 10 v in 2.7v 6v l1 3.3 r1 20k r2 40k c1 33 v out 1.2v/2a pgood r3 100k 0 10 20 30 40 50 60 70 80 90 100 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 efficiency vs. load current load current(a) efficiency (%) v in =3v v in =5v
mp2127 ? 2.7-6v, 2a, 1.2mhz sy nchronous step-do wn converter mp2127 rev. 0.91 www.monolithicpower.com 2 4/27/2010 mps proprietary information. unaut horized photocopy and d uplication prohibited. ? 2010 mps. all rights reserved. ordering information part number* package top marking free air temperature (t a ) MP2127DQ qfn6 (3mm x 3mm) 8g ?40 c to +85 c * for tape & reel, add suffix ?z (e.g. MP2127DQ?z). for rohs compliant packaging, add suffix ?lf (e.g. MP2127DQ?lf?z) package reference top view fb gnd sw 1 2 3 pgood vin pvin 6 5 4 absolute maxi mum ratings (1) pvin, vin to gnd......................?0.3v to + 7.0v sw to gnd .......................... ?0.3v to v in + 0.3v pgood, fb to gnd ...................?0.3v to +6.5v operating temperature............. ?40c to +85c continuous power dissipation?(t a = +25c) (2) ??????????????????....2.5w junction temperature ...............................150c lead temperature ....................................260c storage temperature ............. ?65c to +150c recommended operating conditions (3) supply voltage v in .............................2.7v to 6v operating junct. temp (t j )...... -40 c to +125 c thermal resistance (4) ja jc qfn6 (3mm x 3mm) ...............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.
mp2127 ? 2.7-6v, 2a, 1.2mhz sy nchronous step-do wn converter mp2127 rev. 0.91 www.monolithicpower.com 3 4/27/2010 mps proprietary information. unaut horized photocopy and d uplication prohibited. ? 2010 mps. all rights reserved. electrical characteristics (5) v in = 3.6v, t a = +25 c, unless otherwise noted. parameters symbol condition min typ max units supply current i in v fb = 0.9v 500 750 a thermal shutdown trip threshold t sd hysteresis = 20c 150 c in undervoltage lockout threshold inuv vth rising edge 2.15 2.40 2.65 v in undervoltage lockout hysteresis inuv hys 160 mv t a = +25c 0.784 0.800 0.816 regulated fb voltage v fb -40c t a +85c 0.776 0.800 0.824 v fb input bias current i fb v fb = 0.9v -50 -2 +50 na sw pfet on resistance hs rds-on i sw = 100ma 0.19 0.23 0.27 ? sw nfet on resistance ls rds-on i sw = -100ma 0.16 0.2 0.24 ? duty cycle=100% 2.2 3.0 3.8 sw pfet peak current limit i limit duty cycle=50% (6) 2.5 3.5 4.5 a switching frequency f sw 1.0 1.2 1.4 mhz ovp threshold (pgood output high) v fb ovp- v fb ramps up from v fb nominal operating point 103% v fb ovp threshold (fault detected) v fb ovp+ v fb ramps up from v fb nominal operating point 111% v fb ovp hysteresis 25 mv pgood, output high v fb ovp+ ramp up v fb , starting at v fb 700mv 94% 98.5% v fb pgood, output low v fb ovp- ramp down v fb ,starting at v fb = v fb nom 95% v fb pgood output low voltage isink = 6ma 0.4 v pgood deglitch time 160 s line regulation 4.5v v in 5.5v, i out =100ma 0.1 % load regulation 0a i out 2a 0.1 % notes: 5) production test at +25c. specificati ons over the temperature range are guaranteed by design and characterization. 6) guaranteed by design
mp2127 ? 2.7-6v, 2a, 1.2mhz sy nchronous step-do wn converter mp2127 rev. 0.91 www.monolithicpower.com 4 4/27/2010 mps proprietary information. unaut horized photocopy and d uplication prohibited. ? 2010 mps. all rights reserved. pin functions pin # name description 1 fb feedback input. an external resistor divider fr om the output to gnd, tapped to the fb pin sets the output voltage. 2 gnd ground pin. this pin is the reference grou nd of the regulated output voltage. for this reason care must be taken in pcb layout. suggested to be connected to gnd with copper and vias. connect exposed pad to ground plane for proper thermal performance. 3 sw switch node to the inductor 4 pvin input supply pin for power fet 5 vin input supply pin for controller 6 pgood power-good indicator output. ?low? output i ndicates output is outside the window of regulation level. pgood is pulled down in shutdown. pgood output has 160us deglitch timer to avoid false trigger during transient response.
mp2127 ? 2.7-6v, 2a, 1.2mhz sy nchronous step-do wn converter mp2127 rev. 0.91 www.monolithicpower.com 5 4/27/2010 mps proprietary information. unaut horized photocopy and d uplication prohibited. ? 2010 mps. all rights reserved. typical performanc e characteristics v in = 5v, v out = 1.2v, t a = +25oc, unless otherwise noted. load regulation enabled supply current vs. input voltage v in (v) case temperature rise vs. output current output current (a) duty cycle ipeak vs. duty load current(a) i nput voltage (v) line regulation ipeak (a) 500 520 540 560 580 600 620 640 660 680 02468 0 5 10 15 20 25 30 35 40 0 0.5 1 1.5 2 0 10 20 30 40 50 60 70 80 90 100 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 efficiency vs. load current load current(a) efficiency (%) v in =3v v in =5v 3 3.3 3.6 3.9 4.2 0% 20% 40% 60% 80% 100% -0.20 -0.16 -0.12 -0.08 -0.04 0.00 0.04 0.08 0.12 0.16 0.20 0 0.5 1 1.5 2 normalized output voltage (%) v in =5v v in =3v -0.20 -0.15 -0.10 -0.05 0.00 0.05 0.10 0.15 0.20 234567 normalized output voltage (%) case temperature rise ( o c) i o =0a i o =1a i o =2a i in (ua)
mp2127 ? 2.7-6v, 2a, 1.2mhz sy nchronous step-do wn converter mp2127 rev. 0.91 www.monolithicpower.com 6 4/27/2010 mps proprietary information. unaut horized photocopy and d uplication prohibited. ? 2010 mps. all rights reserved. typical performanc e characteristics (continued) v in = 5v, v out = 1.2v, t a = +25oc, unless otherwise noted. input ripple voltage full load v in 50mv/div v in 5v/div short entry full load power good short recovery full load power up without load power up with 2a load sw 2v/div v out 1v/div v in 5v/div pgood 5v/div i inductor 2a/div sw 5v/div v out 1v/div i inductor 500ma/div pgood 5v/div sw 5v/div v out 1v/div i inductor 500ma/div sw 2v/div v out 500mv/div i inductor 2a/div sw 5v/div v out 500mv/div v in 5v/div i inductor 2a/div sw 5v/div v out 500mv/div v in 5v/div i inductor 2a/div power good sw 2v/div 400ns/div 400ns/div output ripple voltage i out =2a sw 2v/div v out 20mv/div i inductor 2a/div load transient response i out =1a-2a v out 50mv/div i out 1a/div
mp2127 ? 2.7-6v, 2a, 1.2mhz sy nchronous step-do wn converter mp2127 rev. 0.91 www.monolithicpower.com 7 4/27/2010 mps proprietary information. unaut horized photocopy and d uplication prohibited. ? 2010 mps. all rights reserved. functional block diagram main switch (pch) synchronou s rectifier (nch) 0.04 pwm control logic current sense amp feedback error amp pwm slope comp ics 1.2 mhz oscillator osc bias & voltage reference 0.8 v fb sw gnd eao iamp 10 x + - + + - pwmcmp eamp + - 1.1 m pvin vin to controller blocks 17 pf c c r z comp + - comp + - 0.86v 0.74 v 0.86 v 0.74v pgood r i 240 k
mp2127 ? 2.7-6v, 2a, 1.2mhz sy nchronous step-do wn converter mp2127 rev. 0.91 www.monolithicpower.com 8 4/27/2010 mps proprietary information. unaut horized photocopy and d uplication prohibited. ? 2010 mps. all rights reserved. operation the mp2127 is a fixed frequency 1.2mhz current mode 2a step-down converter, optimized for low voltage, li-ion battery powered applications where high efficiency and small size are critical. mp2127 integrates a high side pfet main switch and a low side synchronous rectifier. it always operates in continuous conduction mode, simplifies the control scheme and eliminates the random spectrum noise due to discontinuous conduction mode. the steady state duty cycle d for this mode can be calculated as: % 100 v v % 100 f t d in out osc on = where t on is the main switch on time and f osc is the oscillator frequency (1.2mhz typ.). current mode pwm control slope compensated current mode pwm control provides stable switching and cycle-by-cycle current limiting for superior load and line response as well as protection of the internal main switch and synchronous rectifier. the mp2127 switches at a constant frequency (1.2mhz) and modulates the inductor peak current to regulate the output voltage. specifically, for each cycle the pwm controller forces the inductor peak current to an internal reference level derived from the feedback error voltage. at normal operation, the main switch is turned on at each rise edge of the internal oscillator, and remains on for a certain period of time to ramp up the inductor current. as soon as the inductor current reaches the reference level, the main switch is turned off and immediately the synchronous rectifier will be turned on to provide the inductor current. in forced pwm mode, the synchronous rectifier will stay on until the next oscillator cycle. dropout operation the mp2127 allows the main switch to remain on for more than one switching cycle to increase the duty cycle when 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. in this case, the output voltage becomes the input voltage minus the voltage drop across the main switch and the inductor. maximum load current the mp2127 can operate down to 2.7v input voltage; however the maximum load current decreases at lower input due to a 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. 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 approaches 0.8v. pgood indicator mp2127 provides an open-drain pgood output that becomes high-impedance (open circuit) after output level reaches regulation after startup. pgood is pulled low if the output goes out of regulation level for more than the de-glitch time of 160us, or when device enters shutdown.
mp2127 ? 2.7-6v, 2a, 1.2mhz sy nchronous step-do wn converter mp2127 rev. 0.91 www.monolithicpower.com 9 4/27/2010 mps proprietary information. unaut horized photocopy and d uplication prohibited. ? 2010 mps. all rights reserved. application information output voltage setting the output voltage is set by the external resistor divider: ) 1 ( 8 . 0 2 1 r r v out + ? = the divider ratio also affects the loop bandwidth of the step-down converter. the approximate relationship between them is given below: ) 1 ( 240 1 2 1 1 r r k r bw + ? + to minimize the impact of r1 to loop bandwidth, one should choose r1 much smaller than 240k. some recommended value for common output voltage is listed below: table 1?resistor selection vs. output voltage setting v out r1 r2 1.2v 20k ? (1%) 40.2k ? (1%) 1.8v 49.9k ? (1%) 40.2k ? (1%) 2.5v 84.5k ? (1%) 40.2k ? (1%) inductor selection a 1 h to 10 h 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 ? . see table 2 for recommended inductors and manufacturers. 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 inductor ripple current. choose inductor ripple current approximately 30% of the maximum load current, 2a. the maximum inductor peak current is: 2 i i i l load ) max ( l + = table 2?suggested inductors manufacturer part number inductance ( h) dimensions lxwxh (mm 3 ) toko b1015as- 3r0n 3 8.4x8.3x4 tdk rlf7030t- 3r3m4r1 3.3 7.3x6.8x3.2 input capacitor c in 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. for most applications, a 10 f capacitor is sufficient. output capacitor cout 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. for forced pwm mode operation, the output ripple v out is approximately: ) 1 8 1 ( ) ( out osc esr osc in out in out out c f r l f v v v v v ? ? + ? ? ? ? = f or most applications, a 33 f capacitor is sufficient. thermal dissipation power dissipation shall be considered when operates mp2127 at maximum 2a output current. if the junction temperature rises above 150 c, mp2127 will be shut down by internal thermal protection circuitry.
mp2127 ? 2.7-6v, 2a, 1.2mhz sy nchronous step-do wn converter mp2127 rev. 0.91 www.monolithicpower.com 10 4/27/2010 mps proprietary information. unaut horized photocopy and d uplication prohibited. ? 2010 mps. all rights reserved. the junction-to-ambient thermal resistance of the 6-pin qfn (3mm x 3mm) r ja is 50 c/w. the maximum allowable power dissipation is about1.6w when mp2127 is operating in a 70 c ambient temperature environment: w 6 . 1 w / c 50 c 70 c 150 pd o o o max = ? = pc board layout the high current paths (gnd, in and sw) should be placed very close to the device with short, direct and wide traces. input capacitors should be placed as close as possible to the respective in and gnd pins. the external feedback resistors shall be placed next to the fb pins. keep the switching nodes sw short and away from the feedback network. c1 l1 c2 r4 r1 gnd r2 fb gnd pvin sw vin pgood 4 5 6 1 2 3 r3 c3 c4 gnd vin vout top layer gnd bottom layer
mp2127 ? 2.7-6v, 2a, 1.2mhz sy nchronous step-do wn 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. mp2127 rev. 0.91 www.monolithicpower.com 11 4/27/2010 mps proprietary information. unaut horized photocopy and d uplication prohibited. ? 2010 mps. all rights reserved. package information qfn6 (3mmx3mm) side view top view 1 6 4 3 bottom view 2.90 3.10 1.40 1.60 2.90 3.10 2.20 2.40 0.95 bsc 0.35 0.45 0.80 1.00 0.00 0.05 0.20 ref pin 1 id marking 1.50 0.95 0.40 recommended land pattern 2.90 note: 1) all dimensions are in millimeters. 2) exposed paddle size does not include mold flash. 3) lead coplanarity shall be 0.10 millimeter max. 4) jedec reference is mo-229, variation veea-2. 5) drawing is not to scale. pin 1 id see detail a 2.30 0.80 pin 1 id option a r0.20 typ. pin 1 id option b r0.20 typ. detail a 0.35 0.55 pin 1 id index area

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