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MP2227 24v, 3a, 1.3mhz synchronous step-down converter MP2227 rev. 1.1 www.monolithicpower.com 1 11/21/2011 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. the future of analog ic technology description the MP2227 is an internally compensated 1.3mhz fixed frequency pwm synchronous step-down regulator. MP2227 operates from a 3v to 24v input and generates an adjustable output voltage from 0.8v to 0.9xv in at up to 3a load current. the MP2227 integrates a 160m ? high-side switch and an 80m ? synchronous rectifier for high efficiency without an external schottky diode. with peak current mode control and internal compensation, it is stable with an output ceramic capacitor and a small inductor. fault protection includes hiccup short-circuit protection, cycle-by-cycle current limiting and thermal shutdown. other features include frequency synchronization and soft-start. the MP2227 is available in a small 3mm x 3mm 10-lead qfn package. features ? 3a output current ? input supply range: 3v to 24v ? 160m ? high-side, 80m ? low-side internal power mosfet switches ? all ceramic output capacitor design ? up to 95% efficiency ? 1.3mhz fixed switching frequency ? adjustable output from 0.8v to 0.9xv in ? internal ldo for v cc supply ? 1mhz to 2mhz frequency synchronization ? pok ? thermal shutdown ? cycle-by-cycle current limiting ? hiccup short circuit protection ? 10-lead, 3mm x 3mm qfn package applications ? p/asic/dsp/fpga core and i/o supplies ? printers and lcd tvs ? network and telecom equipment ? point of load regulators for mps green status, please visit mps website under quality assurance. ?mps? and ?the future of analog ic technology? are trademarks of monolithic power systems, inc. typical application efficiency (%) efficiency v in =12v, v out =5v 0 10 20 30 40 50 60 70 80 90 100 0.0 0.5 1.0 1.5 2.0 2.5 3.0 load current ( a ) free datasheet http:///
MP2227 ? 24v, 3a, 1.3mhz sync hronous step-down converter MP2227 rev. 1.1 www.monolithicpower.com 2 11/21/2011 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. ordering information part number* package top marking free air temperature (t a ) MP2227dq qfn10(3mm x 3mm) 7u -40 ? c to +85 ? c * for tape & reel, add suffix ?z (e.g. MP2227dq?z). for rohs compliant packaging, add suffix ?lf (e.g. MP2227dq?lf?z) package reference top view fb pok vin gnd gnd 1 2 3 4 5 en/sync vcc bst sw sw 10 9 8 7 6 exposed pad on backside absolute maxi mum ratings (1) vin to gnd ...................................-0.3v to +28v sw to gnd ...........................-0.3v to v in + 0.3v .............................-2.5v to v in + 2.5v for < 50ns fb, en/sync, vcc to gnd...........-0.3v to +6.5v pok, sync_out to gnd .............-0.3v to +6.5v bs to sw .....................................-0.3v to +6.5v 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 ..............................3v to 24v output voltage v out ..................0.8v to 0.9 x v in max operating junct. temp (t j ).............+125c thermal resistance (4) ja jc qfn10 (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. free datasheet http:///
MP2227 ? 24v, 3a, 1.3mhz sync hronous step-down converter MP2227 rev. 1.1 www.monolithicpower.com 3 11/21/2011 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. electrical characteristics (5) v in =12v, t a = +25 ? c, unless otherwise noted. parameters condition min typ max units quiescent supply current v en = high v fb = 0.85v, not switching 1 ma shutdown current v en = 0v 1 a v cc under voltage lockout threshold rising edge 2.7 2.95 v v cc under voltage lockout hysteresis 300 mv in under voltage lockout threshold, rising edge 2.85 2.95 v in under voltage lockout hysteresis 300 mv t a = +25c 0.784 0.800 0.816 v regulated fb voltage -40c t a +85c 0.780 0.820 v fb input current v fb = 0.85v -50 50 na en high threshold -40c t a +85c 1.6 v en low threshold -40c t a +85c 0.4 v high-side switch on-resistance i sw = 300ma 160 m ? low-side switch on-resistance i sw = ?300ma 80 m ? sw leakage current v en = 0v; v in = 12v v sw = 0v or 12v -1 1 a bs under voltage lockout threshold 1.8 v high-side switch current limit sourcing 4.5 a low-side switch current limit sinking 2.5 a oscillator frequency 1 1.3 1.6 mhz maximum synch frequency 2 mhz minimum synch frequency 1 mhz minimum on time 50 ns maximum duty cycle 90 % pok upper trip threshold fb respect to the nominal value 10 % pok lower trip threshold fb respect to the nominal value -10 % pok output voltage low i sink = 5ma 0.4 v pok deglitch timer 40 s sync_input high level v cc = 5v, source 5ma 4.6 v sync_input low level v cc = 5v, sink 5ma 0.4 v thermal shutdown threshold hysteresis = 20c 150 c note: 5) production test at +25c. specificat ions over the temperature range are guaranteed by design and characterization. free datasheet http:///
MP2227 ? 24v, 3a, 1.3mhz sync hronous step-down converter MP2227 rev. 1.1 www.monolithicpower.com 4 11/21/2011 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. pin functions pin # name description 1 fb feedback. this is the input to the error amplif ier. an external resistive divider connected between the output and gnd is compared to t he internal 0.8v reference to set the regulation voltage. 2 pok open drain power good output. ?high? output indicates vout is within 10% window. ?low? output indicates vout is out of 10% window. pok is pulled down in shutdown. 3 in input supply. this supplies power to the high side switch. a decoupling capacitor to ground is required close to this pin to reduce switching spikes. 4, 5 gnd ground. connect these pins with larger copper areas to the negative terminals of the input and output capacitors. 6,7 sw switch node connection to the inductor. these pins connect to the internal high and low- side power mosfet switches. all sw pins must be connected together externally. 8 bst bootstrap. a capacitor between this pin and sw provides a floating supply for the high-side gate driver. 9 vcc bias supply. provide 5v to this pin when t he input voltage is less than 5v. otherwise it does not need external supply. this supplies power to both the internal control circuit and the gate drivers. a decoupling capacitor to ground is required close to this pin. 10 en/sync enable and frequency synchronization input pin. forcing this pin below 0.4v shuts down the part. forcing this pin above 1.6v turns on the part. applying a 1mhz to 2mhz clock signal to this pin synchronizes the internal oscillator frequency to the external source. to enable the device, connect this pin to v in through a 100k ? resistor. when v in is less than 5v and v cc is externally biased, this pin can also be connected to v cc through a 100k ? resistor. free datasheet http:///
MP2227 ? 24v, 3a, 1.3mhz sync hronous step-down converter MP2227 rev. 1.1 www.monolithicpower.com 5 11/21/2011 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. typical performanc e characteristics v in = 12v, v out = 1.8v, c 1a = 22 f, c 2a = c 2b = 22 f, l = 1.5h, t a = +25oc, unless otherwise noted. free datasheet http:///
MP2227 ? 24v, 3a, 1.3mhz sync hronous step-down converter MP2227 rev. 1.1 www.monolithicpower.com 6 11/21/2011 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. typical performanc e characteristics (continued) v in = 12v, v out = 1.8v, c 1a = 22 f, c 2a = c 2b = 22 f, l = 1.5h, t a = +25oc, unless otherwise noted. v sys 5v/div. v sw 10v/div. v out 2v/div. i l 2a/div. v sys 20v/div. v sw 20v/div. v out 2v/div. i l 2a/div. v en 2v/div. v pg 5v/div. v out 5v/div. i l 2a/div. v en 2v/div. v pg 5v/div. v out 5v/div. i l 2a/div. v sys 10v/div. v out 20v/div. v out 1v/div. i out 2a/div. v sys 10v/div. v sw 10v/div. v out 1v/div. i l 2a/div. v sys 10v/div. v sw 10v/div. v out 1v/div. i l 2a/div. steady state v sys = 5v, v en put to v in , v out = 3.3v, i out = 3a power ramp up v in = 12v, v en put to v in , v out = 1.8v, i out = 2a power ramp down v in = 12v, v en put to v in , v out = 1.8v, i out = 2a steady state v in = 26v, v en put to v in , v out = 3.3v, i out = 3a enable up v in = 12v, v en = 0-3v, v out = 5v, i out = 3a, resistor load enable down v in = 12v, v en = 3-0v, v out = 5v, i out = 3a, resistor load transient response v in = 18v, v in ,v out = 1.8v, i out = 3a i l 2a/div. v out 1v/div. i l 2a/div. short circuit v in = 18v, v en put to v in , v out = 1.8v short circuit recovery v in = 18v, v en put to v in, v out = 1.8v free datasheet http:///
MP2227 ? 24v, 3a, 1.3mhz sync hronous step-down converter MP2227 rev. 1.1 www.monolithicpower.com 7 11/21/2011 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. functional block diagram figure 1?functional block diagram free datasheet http:///
MP2227 ? 24v, 3a, 1.3mhz sync hronous step-down converter MP2227 rev. 1.1 www.monolithicpower.com 8 11/21/2011 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. typical application free datasheet http:///
MP2227 ? 24v, 3a, 1.3mhz sync hronous step-down converter MP2227 rev. 1.1 www.monolithicpower.com 9 11/21/2011 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. functional description pwm control the MP2227 is a constant frequency peak- current-mode control pwm switching regulator. refer to the functional block diagram. the high side n-channel dmos power switch turns on at the beginning of each clock cycle. the current in the inductor increases until the pwm current comparator trips to turn off the high side dmos switch. the peak inductor current at which the current comparator shuts off the high side power switch is controlled by the comp voltage at the output of feedback error amplifier. the transconductance from the comp voltage to the output current is set at 11.25a/v. this current-mode control greatly simplifies the feedback compensation design by approximating the switching converter as a single-pole system. only type ii compensation network is needed, which is integrated into the MP2227. the loop bandwidth is adjusted by changing the upper resistor value of the resistor divider at the fb pin. the internal compensation in the MP2227 simplifies the compensation design, minimizes external component counts, and keeps the flexibility of external compensation for optimal stability and transient response. enable and frequency synchronization (en/sync pin) this is a dual function input pin. forcing this pin below 0.4v for longer than 4us shuts down the part; forcing this pin above 1.6v for longer than 4s turns on the part. applying a 1mhz to 2mhz clock signal to this pin also synchronizes the internal oscillator frequency to the external clock. when the external clock is used, the part turns on after detecting the first few clocks regardless of duty cycles. if any on or off period of the clock is longer than 4s, the signal will be intercepted as an enable input and disables the synchronization. soft-start and output pre-bias startup when the soft-start period starts, an internal current source begins charging an internal soft- start capacitor. during soft-start, the voltage on the soft-start capacitor is connected to the non- inverting input of the error amplifier. the soft- start period lasts until the voltage on the soft- start capacitor exceeds the reference voltage of 0.8v. at this point the reference voltage takes over at the non-inverting error amplifier input. the soft-start time is internally set at 120s. if the output of the MP2227 is pre-biased to a certain voltage during startup, the ic will disable the switching of both high-side and low-side switches until the voltage on the internal soft- start capacitor exceeds the sensed output voltage at the fb pin. over current protection the MP2227 offers cycle-to-cycle current limiting for both high-side and low-side switches. the high-side current limit is relatively constant regardless of duty cycles. when the output is shorted to ground, causing the output voltage to drop below 70% of its nominal output, the ic is shut down momentarily and begins discharging the soft start capacitor. it will restart with a full soft-start when the soft- start capacitor is fully discharged. this hiccup process is repeated until the fault is removed. bootstrap (bst pin) the gate driver for the high-side n-channel dmos power switch is supplied by a bootstrap capacitor connected between the bs and sw pins. when the low-side switch is on, the capacitor is charged through an internal boost diode. when the low-side switch is off and the high-side switch turns on, the voltage on the bootstrap capacitor is boosted above the input voltage and the internal bootstrap diode prevents the capacitor from discharging. no external bootstrap diode is required for typical applications. for applications with low input vcc voltage or where output voltage is very close to input voltage, an external schottky diode may be connected from the vcc to bs pins to charge the bootstrapped capacitor more strongly for increased gate drive voltage. when using the external bootstrap diode, a resistor at the regulator output or a minimal load current may be required as the bootstrapped capacitor free datasheet http:///
MP2227 ? 24v, 3a, 1.3mhz sync hronous step-down converter MP2227 rev. 1.1 www.monolithicpower.com 10 11/21/2011 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. always see the supply voltage even when the part is disabled. input uvlo both vcc and in pins have input uvlo detection. until both vcc and in voltage under voltage lockout threshold, the parts remain in shutdown condition. there are also under voltage lockout hysesteres at both vcc and in pins. free datasheet http:///
MP2227 ? 24v, 3a, 1.3mhz sync hronous step-down converter MP2227 rev. 1.1 www.monolithicpower.com 11 11/21/2011 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. application information setting the output voltage the external resistor divider sets the output voltage (see typical application schematic). the feedback resistor r1 also sets the feedback loop bandwidth with the internal compensation capacitor (see figure 1). the relation between r1 and feedback loop bandwidth ( f c ) , output capacitance ( c o ) is as follows: 6 co 1.24 10 r1(k ) f(khz) c(f) ? ?? ?? . the feedback loop bandwidth (f c ) is no higher than 1/10 th of switching frequency of MP2227. in the case of ceramic capacitor as c o , it?s usually set to be in the range of 50khz and 150khz for optimal transient performance and good phase margin. if electrolytic capacitor is used, the loop bandwidth is no higher than 1/4 th of the esr zero frequency ( f esr ). f esr is given by: esr esr o 1 f 2r c ? ?? ? for example, choose f c =70khz with ceramic capacitor, c o =47uf, r1 is estimated to be 400k ? . r2 is then given by: out r1 r2 v 1 0.8v ? ? table 1?resistor selection vs. output voltage setting v out (v) r1 (k ? ) r2 (k ? ) l ( h) c out (ceramic) 1.2 400 806 0.47 h-1 h 47 f 1.5 400 453 0.47 h-1 h 47 f 1.8 400 316 0.47 h-1 h 47 f 2.5 400 187 0.47 h-1 h 47 f 3.3 400 127 0.47 h-1 h 47 f selecting the inductor a 0.47h to 1h 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 <10m ? . see table 2 for recommended inductors and manufacturers. for most designs, the inductance value can be derived from the following equation: out in out in l osc vx(v v) l vxixf ? ? ? where ? il is inductor ripple current. choose inductor ripple current approximately 30% of the maximum load current, 3a.the maximum inductor peak current is: l l(max) load i ii 2 ? ?? under light load conditions, 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. for most applications, a 47f capacitor is sufficient. free datasheet http:///
MP2227 ? 24v, 3a, 1.3mhz sync hronous step-down converter MP2227 rev. 1.1 www.monolithicpower.com 12 11/21/2011 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. table 2?suggested surface mount inductors manufacturer part number inductance ( h) max dcr (m ? ) current rating (a) dimensions l x w x h (mm 3 ) wurth electronics 744310055 0.55 4.5 14 76.93 744310095 0.95 7.4 11 76.93 toko b1015as-1r0n 1 11 6.9 8.48.34 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. if electrolytic capacitor is used, pay attention to output ripple voltage, extra heating, and the selection of feedback resistor r1 (refer to ?output voltage setting? section) due to large esr of electrolytic capacitor. the output ripple ? v out is approximately: out in out out in osc osc vx(v v) 1 v x(esr ) v xf xl 8xf xc3 ? ?? ? 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. a 0.1 f-1 f ceramic is recommended for vcc supply. c5 must be placed as close as possible to ?vcc? pin and ?gnd? pin. the external feedback resistors shall be placed next to the fb pin. keep the switching node sw short and away from the feedback network. please see ev2227eq datasheet for detailed info. free datasheet http:///
MP2227 ? 24v, 3a, 1.3mhz sync hronous step-down converter notice: the information in this document is subject to change wi thout notice. please contact m ps for current specifications. users should warrant and guarantee that third party intellectual property rights ar e not infringed upon when integrating mps products into any application. mps will not assume any legal responsibility for any said applications. MP2227 rev. 1.1 www.monolithicpower.com 13 11/21/2011 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. package information qfn10 (3mm x 3mm) side view top view 1 10 6 5 bottom view 2.90 3.10 1.45 1.75 2.90 3.10 2.25 2.55 0.50 bsc 0.18 0.30 0.80 1.00 0.00 0.05 0.20 ref pin 1 id marking 1.70 0.50 0.25 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) drawing conforms to jedec mo-229, variation veed-5. 5) drawing is not to scale. pin 1 id see detail a 2.50 0.70 pin 1 id option b r0.20 typ. pin 1 id option a r0.20 typ. detail a 0.30 0.50 pin 1 id index area free datasheet http:///

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