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MP8714 high-efficiency, 10a, 17v, synchronous, step-down converter with external soft start and power good MP8714 rev.1.0 www.monolithicpower.com 1 12/27/2016 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2016 mps. all rights reserved. the future of analog ic technology description the MP8714 is a high-frequency, synchronous, rectified, step-down, switch-mode converter. this fully integrated solution achieves 10a of output current with excellent load and line regulation over a wide input supply range. current mode operation provides fast transient response and eases loop stabilization. en/sync supports external clock synchronization, and an open-drain power good pin (pg) indicates when the output voltage is in the nominal range. full protection features include over-voltage protection (ovp), hiccup over-current protection (ocp), and thermal shutdown. the MP8714 requires a minimal number of readily available, standard, external components and is available in a qfn-14 (3mmx4mm) package. features ? wide 4.5v to 17v operating input range ? 10a continuous output current ? 26m ? high-side, 11m ? low-side r ds(on) for internal power mosfets ? 200khz - 2mhz synchronized external clock ? programmable soft-start (ss) time ? open-drain power good (pg) indicator ? output over-voltage protection (ovp) ? thermal shutdown ? available in a small qfn-14 (3mmx4mm) package applications ? flat-panel televisions and monitors ? set-top boxes ? distributed power systems all mps parts are lead-free, halogen-free, and adhere to the rohs directive. for mps green status, please visit the mps website under quality assurance. ?mps? and ?the future of analog ic technology? are registered trademarks of monolithic power systems, inc. typical application 0.01 30 40 50 60 70 80 90 100 0.10 1.00 10.00
MP8714 ? 17v, 10a, synchrono us, step-down converter MP8714 rev.1.0 www.monolithicpower.com 2 12/27/2016 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2016 mps. all rights reserved. ordering information part number* package top marking MP8714gle qfn-14 (3mmx4mm) see below for tape & reel, add suffix ?z (e.g. MP8714gle?z) top marking mp: mps prefix y: year code w: week code 8714: first four digits of the part number lll: lot number e: product code package reference top view qfn-14 (3mmx4mm)
MP8714 ? 17v, 10a, synchrono us, step-down converter MP8714 rev.1.0 www.monolithicpower.com 3 12/27/2016 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2016 mps. all rights reserved. absolute maximum ratings (1) vin .................................................. -0.3v to 19v v sw .................................... -0.6v (-6v for <10ns) to 20v (24v for <10ns) v bst ................................................... v sw + 5.5v all other pins ............................. -0.3v to 5.5v (2) continuous power dissipation (t a = +25c) (3) qfn-14 (3mmx4mm) ................................. 2.6w junction temperature ................................ 150c lead temperature ..................................... 260c storage temperature .................. -65c to 150c recommended operating conditions (4) supply voltage (vin) ........................ 4.5v to 17v output voltage (vout) ........................... 0.6v to vin x d max or 5.5v (5) operating junction temp. (t j ). .. -40c to +125c thermal resistance (6) ja jc qfn-14 (3mmx4mm) ............. 48 ....... 11 ... c/w notes: 1) exceeding these ratings may damage the device. 2) for details of en/sync?s abs max rating, please refer to the enable/sync control section on page 13. 3) 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 produces an excessive die temperature, causing the regulator to go into thermal shutdown. internal thermal shutdown circuitry protects the device from permanent damage. 4) the device is not guaranteed to function outside of its operating conditions. 5) the output voltage cannot exceed the 5.5v absolute maximum value at any input condition. 6) measured on jesd51-7, 4-layer pcb.
MP8714 ? 17v, 10a, synchrono us, step-down converter MP8714 rev.1.0 www.monolithicpower.com 4 12/27/2016 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2016 mps. all rights reserved. electrical characteristics v in = 12v, t j = -40c to 125c (7) , unless otherwise noted. typical value is based on the average value when t j = 25c. parameter symbol condition min typ max units supply current (shutdown) i in v en = 0v 9 13 a supply current (quiescent) i q v en = 2v, no switching 560 800 a hs switch on resistance hs rds-on v bst-sw = 5v 26 m ? ls switch on resistance ls rds-on v cc = 5v 11 m ? switch leakage sw lkg v en = 0v, v sw = 12v or 0v, t j = 25c 1 a high-side current limit (8) i limit h under 40% duty cycle 11.7 14 a oscillator frequency f sw t j = 25c 400 500 570 khz t j = -40c to 125c 350 600 foldback frequency f vout v fb = 150mv 0.5 f sw sync frequency range f sync 200 2000 khz maximum duty cycle d max v fb = 500mv, f s = 500khz 93 95 % minimum on time (8) t on min 40 ns fb voltage v fb t j = 25c 594 600 606 mv t j = -40c to 85c (8) 588 612 fb current i fb v fb = 620mv 10 50 na en/sync pull-up current i en_pu v en = 0v, t j = 25c 4.3 6.2 7.5 a v en = 0v, t j = -40c to 125c 3.2 8 en/sync rising threshold v en_rise t j = 25c 1.27 1.38 1.48 v t j = -40c to 125c 1.25 1.5 en/sync hysteresis v en_hys t j = 25c 100 150 200 mv t j = -40c to 125c 80 220 en/sync turn-off delay en td-off 10 s vin under-voltage lockout threshold rising inuv vth t j = 25c 4.03 4.16 4.29 v t j = -40c to 125c 4 4.32 vin under-voltage lockout threshold hysteresis inuv hys 510 610 700 mv power good uv threshold rising pgvth-hi t j = 25c 0.85 0.9 0.94 vout t j = -40c to 125c 0.84 0.95 power good uv threshold falling pgvth-lo t j = 25c 0.64 0.7 0.73 vout t j = -40c to 125c 0.63 0.74 power good deglitch time pgtd 100 160 s
MP8714 ? 17v, 10a, synchrono us, step-down converter MP8714 rev.1.0 www.monolithicpower.com 5 12/27/2016 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2016 mps. all rights reserved. electrical characteristics (continued) vin = 12v, t j = -40c to 125c (7) , unless otherwise noted. ty pical value is based on average value when t j = 25c. parameter symbol condition min typ max units ovp discharge resistor r ov from vout to gnd 35 70 ? ovp rising threshold v en_rise fb pin, t j = 25c 114% 120% 126% v ref fb pin, t j = -40c to 125c 113% 127% ovp falling threshold v en fall fb pin 101% 105% 108% v ref soft-start current i ss 7 10 12 a vcc voltage v cc t j = -40c to 125c 4.75 4.95 5.1 v vcc load regulation i cc = 5ma 1 3 % thermal shutdown ( 8) t tsd 160 c thermal hysteresis ( 8) t tsd hys 20 c notes: 7) not tested in production, guaranteed by over-temperature correlation. 8) guaranteed by design and characterization test.
MP8714 ? 17v, 10a, synchrono us, step-down converter MP8714 rev.1.0 www.monolithicpower.com 6 12/27/2016 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2016 mps. all rights reserved. typical performance characteristics vin = 12v, vout = 1v, l = 1.5h, t a = 25c, unless otherwise noted. 1.2 1.25 1.3 1.35 1.4 1.45 1.5 1.55 1.6 -40 -20 0 20 40 60 80 100 120125 300 350 400 450 500 550 600 650 700 4.5 6 7.5 9 10.5 12 13.5 15 16.5 4.5 6 7.5 9 10.5 12 13.5 15 16.5 4 5 6 7 8 9 10 11 12 13 14 15 4 4.05 4.1 4.15 4.2 4.25 4.3 4.35 4.4 400 420 440 460 480 500 520 540 560 8 9 10 11 12 13 14 15 16 17 10 20 30 40 50 60 70 12 12.5 13 13.5 14 14.5 15 15.5 16 -40 -20 0 20 40 60 80 100 120125 -40 -20 0 20 40 60 80 100 120125 -40 -20 0 20 40 60 80 100 120125 -40 -20 0 20 40 60 80 100 120125 582 586 590 594 598 602 606 610 614 618
MP8714 ? 17v, 10a, synchrono us, step-down converter MP8714 rev.1.0 www.monolithicpower.com 7 12/27/2016 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2016 mps. all rights reserved. typical performanc e characteristics (continued) vin = 12v, vout = 1v, l = 1.5h, t a = 25c, unless otherwise noted.
MP8714 ? 17v, 10a, synchrono us, step-down converter MP8714 rev.1.0 www.monolithicpower.com 8 12/27/2016 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2016 mps. all rights reserved. typical performanc e characteristics (continued) performance waveforms are tested on the evaluation board of the design example section. vin = 12v, vout = 1v, l = 1.5h, t a = 25c, unless otherwise noted. v out 500mv/div. v pg 5v/div. v sw 20v/div. i l 10a/div. v out 500mv/div. v pg 5v/div. v sw 20v/div. i l 10a/div. v out 500mv/div. v pg 5v/div. v en 5v/div. v sw 20v/div. i l 1a/div. short entry i out = 0a short recovery i out = 0a start-up through enable i out = 0a start-up through enable i out = 10a shutdown through enable i out = 0a shutdown through enable i out = 10a start-up through input voltage i out = 0a start-up through input voltage i out = 10a shutdown through input voltage i out = 0a v out 500mv/div. v pg 5v/div. v en 5v/div. v sw 10v/div. i l 10a/div. v out 500mv/div. v pg 5v/div. v in 10v/div. v sw 10v/div. i l 1a/div. v out 500mv/div. v pg 5v/div. v in 10v/div. v sw 10v/div. i l 10a/div. v out 500mv/div. v pg 5v/div. v in 10v/div. v sw 10v/div. i l 1a/div. v out 500mv/div. v pg 5v/div. v en 5v/div. v sw 20v/div. i l 1a/div. v out 500mv/div. v pg 5v/div. v en 5v/div. v sw 10v/div. i l 10a/div.
MP8714 ? 17v, 10a, synchrono us, step-down converter MP8714 rev.1.0 www.monolithicpower.com 9 12/27/2016 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2016 mps. all rights reserved. typical performanc e characteristics (continued) performance waveforms are tested on the evaluation board of the design example section. v out /ac 10mv/div. v out /ac 100mv/div. v in /ac 100mv/div. v sw 10v/div. i l 5a/div. v out /ac 10mv/div. v in /ac 10mv/div. v sw 10v/div. i l 500ma/div. shutdown through input voltage i out = 10a input/output ripple i out = 10a input/output ripple i out = 0a, pfm load transient response i out = 5a to 10a v out 500mv/div. v pg 5v/div. v in 5v/div. v sw 10v/div. i l 10a/div. i l 5a/div.
MP8714 ? 17v, 10a, synchrono us, step-down converter MP8714 rev.1.0 www.monolithicpower.com 10 12/27/2016 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2016 mps. all rights reserved. pin functions qfn-14 pin# name description 1 bst bootstrap. a capacitor is required between sw and bst to form a floating supply across the high-side switch driver. 2 sw switch output. connect sw using a wide pcb trace. 3, 4, 6 nc no connection. leave nc floating. 5 en/sync enable/synchronize. drive en/sync high to enabl e the MP8714. en/sync has an internal 6.2a pull-up current to 5v, so t he MP8714 can start-up automatically when en/sync is floating. apply an external cl ock to en/sync to change the switching frequency. 7 pg power good indication. pg is an open-drain structure. pg switches low if the output voltage is out of regulation window. pg only indicates an under-voltage (uv) condition. 8 pgnd system power ground. pgnd is the reference ground of the regulated output voltage. requires special consideration during pcb layout. connect pgnd to the ground plane with copper traces and vias. 9 vin supply voltage. the MP8714 operates from a 4.5v to 17v input rail. a ceramic capacitor is required to decouple the input rail. connect vin using a wide pcb trace. 10 vout sense input of the output voltage. connect vout to the positive terminal of the load. 11 fb feedback. connect fb to the tap of an external resistor divider from the output to gnd to set the output voltage in a fb control loop. 12 ss soft start. connect a capacitor from ss to ground to set the soft-start time. 13 vcc internal ldo regulator output. decouple vcc with a 0.47f capacitor. 14 agnd signal ground. agnd is not internally connected to system ground directly. ensure that agnd is connected to system ground during pcb layout.
MP8714 ? 17v, 10a, synchrono us, step-down converter MP8714 rev.1.0 www.monolithicpower.com 11 12/27/2016 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2016 mps. all rights reserved. block diagram ovp threshold k figure 1: functional block diagram
MP8714 ? 17v, 10a, synchrono us, step-down converter MP8714 rev.1.0 www.monolithicpower.com 12 12/27/2016 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2016 mps. all rights reserved. operation the MP8714 is a high-frequency, synchronous, rectified, step-down, switch-mode converter with built-in power mosfets. the MP8714 offers a very compact solution that achieves 10a of output current with excellent load and line regulation over a wide input supply range. the MP8714 has three working modes: continuous conduction mode (ccm), advanced asynchronous modulation (aam) mode, and discontinuous conduction mode (dcm). ccm control operation in continuous conduction mode (ccm), the internal clock initiates a pulse-width modulation (pwm) cycle. the high-side mosfet (hs- fet) turns on and remains on until v ilsense reaches the value set by the comp voltage (v comp ). after a period of dead time, the low- side mosfet (ls-fet) turns on and remain on until the next clock cycle begins. the MP8714 repeats this operation in every clock cycle to regulate the output voltage. if v ilsense does not reach the value set by v comp (500khz switching frequency) within 95% of one pwm period, the hs-fet is forced off. aam control operation in light-load condition, the MP8714 works in advanced asynchronous modulation (aam) mode (see figure 2). v aam is an internal, fixed voltage when the input and output voltages are fixed. v comp is the error amplifier output which represents peak inductor current information. when v comp is lower than v aam , the internal clock is blocked, so the MP8714 skips some pulses and achieves light-load power save. refer to the related application note (an032) for more detail. the internal clock resets whenever v comp is higher than v aam . simultaneously, the hs-fet turns on and remains on until v ilsense reaches the value set by v comp. the light-load feature in this device is optimized for 12v input applications. figure 2: simplified aam control logic dcm control operation v comp ramps up with the increasing output current. when its minimum value exceeds v aam , the MP8714 enters discontinuous conduction mode (dcm) (see figure 3). in this mode, the internal clock initiates the pwm cycle. the hs- fet turns on and remains on until v ilsense reaches the value set by v comp . after a period of dead time, the ls-fet turns on and remain on until the inductor current value decreases to zero. the MP8714 repeats this same operation in every clock cycle to regulate the output voltage. figure 3: dcm control operation vcc regulator a 5v internal regulator powers most of the internal circuitries. this regulator takes the vin input and operates in the full vin range. when vin is greater than 5.0v, the output of the regulator is in full regulation. when vin is lower than 5.0v, the output voltage decreases and follows the input voltage. a 0.47 f ceramic capacitor is required for decoupling purposes. error amplifier (ea) the error amplifier compares the fb voltage with the internal 0.6v reference (ref) and outputs a comp voltage, which is used to control the power mosfet current. the optimized internal compensation
MP8714 ? 17v, 10a, synchrono us, step-down converter MP8714 rev.1.0 www.monolithicpower.com 13 12/27/2016 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2016 mps. all rights reserved. networkminimizes the external component count and implifies control loop design. enable control (en/sync) en/sync is a digital control pin that turns the regulator on and off. drive en/sync high to turn on the regulator; drive en/sync low to turn off the regulator. an internal 6.2a pull-up current to a 5v power supply allows for automatic start-up when en/sync is floating. en/sync is clamped internally using a 5.7v series zener diode (see figure 4). connecting the en/sync input through a pull-up resistor to the voltage on vin limits the en/sync input current to less than 100a. for example, with 12v connected to vin, r pullup (12v - 5.7v) 100a = 63k ? . connecting en/sync to a voltage source directly without a pull-up resistor requires limiting the amplitude of the voltage source to 5.5v to prevent damage to the zener diode. figure 4: 5.7v zener diode connection for external clock synchronization, connect a clock with a frequency range between 200khz and 2mhz to en/sync. the internal clock rising edge synchronizes with the external clock rising edge once the external clock is present. set the external clock signal with a pulse width less than 80% of one internal clock cycle time. under-voltage lockout (uvlo) under-voltage lockout (uvlo) protects the chip from operating at an insufficient supply voltage. the MP8714 uvlo comparator monitors the output voltage of the internal regulator (vcc). the uvlo rising threshold is about 4.16v, while its falling threshold is 3.55v. soft start (ss) the MP8714 employs a soft start (ss) mechanism to ensure smooth output during power-up. when en/sync becomes high, an internal current source (10 a) charges up the ss capacitor. the ss capacitor voltage takes over the ref voltage to the pwm comparator. the output voltage smoothly ramps up with the ss voltage. once the ss voltage reaches the same level as the ref voltage, it continues ramping up while v ref takes over the pwm comparator. at this point, the soft start finishes and MP8714 enters into steady-state operation. the ss capacitor value can be determined with equation (1): ?? ?? ?? ?? ? ? ? ss ss ss ref tmsi a cnf vv (1) if the output capacitors have a large capacitance value, do not set the ss time to be too small; otherwise, the current limit can be easily reached during ss. pre-bias start-up the MP8714 has been designed for monotonic start-up into a pre-biased output voltage. if the output is pre-biased to a certain voltage during start-up, the voltage on the soft-start capacitor is charged. when the soft-start capacitor?s voltage exceeds the sensed output voltage at fb, the part turns on the high-side and low-side power switches sequentially. the output voltage begins to ramp up following the soft-start slew rate. power good (pg) indicator the MP8714 uses a power good (pg) output to indicate whether the output voltage of the module is ready or not. pg is an open-drain output. connect pg to vcc or another voltage source through a pull-up resistor (e.g.: 100k ? ). when the input voltage is applied, pg is pulled down to gnd. when v fb is above 90% of v ref , pg is pulled high after a 100s delay. during normal operation, pg is pulled low when v fb drops below 70% of v ref after a 100s delay. when uvlo or otp occurs, pg is pulled low immediately. when over-current (oc) occurs, pg is pulled low when v fb drops below 70% of v ref after a 100s delay. pg does not respond to an output over-voltage condition.
MP8714 ? 17v, 10a, synchrono us, step-down converter MP8714 rev.1.0 www.monolithicpower.com 14 12/27/2016 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2016 mps. all rights reserved. output over-voltage protection (ovp) the MP8714 monitors both fb and vout to detect an over-voltage event. when the feedback voltage rises higher than 120% of the internal reference voltage, the controller enters linear discharge mode. during this period, a 35 ? resistor connected between vout and ground discharges the output and keeps it within the normal range. once the output voltage falls below 105% of the reference, the controller exits linear discharge mode. over-current protection (ocp) and hiccup the MP8714 has a cycle-by-cycle over-current limit. when the inductor current peak value exceeds the set current limit threshold, the hs- fet turns off, and the ls-fet turns on and remains on until the inductor current falls below the internal valley current limit threshold. the valley current limit circuit is employed to decrease the operation frequency after the peak current limit threshold is triggered. meanwhile, the output voltage drops until v fb is below the under-voltage (uv) threshold (typically 30% below the reference). once uv is triggered, the MP8714 enters hiccup mode to restart the part periodically. this protection mode is especially useful when the output is dead-shorted to ground. the average short- circuit current is reduced greatly to alleviate thermal issues and protect the regulator. the MP8714 exits hiccup mode once the over- current condition is removed. thermal shutdown thermal shutdown prevents the chip from operating at exceedingly high temperatures. when the silicon die temperature exceeds 160c, the entire chip shuts down. when the temperature is below its lower threshold (typically 140c), the chip is enabled again. floating driver and bootstrap charging an external bootstrap capacitor powers the floating power mosfet driver. this floating driver has its own uvlo protection. this uvlo?s rising threshold is 2.2v with a hysteresis of 150mv. the bootstrap capacitor voltage is regulated internally by vin through d1, m1, c5, l1, and c2 (see figure 5). if vin - v sw exceeds 5v, u1 regulates m1 to maintain a 5v bst voltage across c5. figure 5: internal bootstrap charging circuit start-up and shutdown if both vin and en/sync exceed their respective thresholds, the chip starts up. the reference block starts first, generating stable reference voltage and currents, and then the internal regulator is enabled. the regulator provides a stable supply for the remaining circuitries. three events can shut down the chip: en/sync low, vin low, and thermal shutdown. in the shutdown procedure, the signaling path is blocked first to avoid any fault triggering. v comp and the internal supply rail are then pulled down. the floating driver is not subject to this shutdown command.
MP8714 ? 17v, 10a, synchrono us, step-down converter MP8714 rev.1.0 www.monolithicpower.com 15 12/27/2016 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2016 mps. all rights reserved. application information setting the output the reference voltage and external resistor divider can set the output voltage through fb. the feedback resistors r1 and r3 set the feedback loop bandwidth with the internal compensation capacitor. choose a value for r1 first, and then calculate r2 with equation (2): 1 v v r1 r2 ref out ? ? (2) the t-type network is highly recommended (see figure 6). figure 6: t-type network table 1 lists the recommended feedback resistors value for common output voltages. table 1: resistor selection for common output voltages (9) vout (v) r1 (k ? ) r2 (k ? ) r3 (k ? ) c6 (pf) l (h) 0.9 80.6 (1%) 162 (1%) 51 (1%) 22 1.5 1.0 80.6 (1%) 120 (1%) 51 (1%) 22 1.5 1.2 80.6 (1%) 80.6 (1%) 40.2 (1%) 22 1.5 2.5 60.4 (1%) 19.1 (1%) 30 (1%) 22 2.2 3.3 60.4 (1%) 13.3 (1%) 20 (1%) 33 3.3 5 60.4 (1%) 8.25 (1%) 20 (1%) 33 3.3 note: 9) the recommended parameters are based on a 12v input voltage and 22fx4 output capacitor. different input voltage and output capacitor values may affect the selection of r1, r2, r3, and c6. for other components? parameters, please refer to the typical application circuits on page 18. selecting the inductor use a 0.47h to 10h inductor with a dc current rating at least 25% higher than the maximum load current for most applications. for the highest efficiency, use an inductor with a dc resistance less than 15m ? . for most designs, the inductance value can be derived from equation (3): out in out 1 in l osc v(vv) l vif ?? ? ?? ? (3) where ? i l is the inductor ripple current. choose the inductor ripple current to be approximately 30% of the maximum load current. the maximum inductor peak current can be calculated with equation (4): 2 i i i l load ) max ( l ? ? ? (4) use a larger inductor for improved efficiency under light-load conditions below 100ma. selecting the input capacitor the input current to the step-down converter is discontinuous and therefore requires a capacitor to supply ac current to the step-down converter while maintaining the dc input voltage. use low esr capacitors for the best performance. ceramic capacitors with x5r or x7r dielectrics are recommended for best results because of their low esr and small temperature coefficients. for most applications, use two 22f capacitors. since c1 absorbs the input switching current, it requires an adequate ripple current rating. the rms current in the input capacitor can be estimated with equation (5): ? ? ? ? ? ? ? ? ? ? ? ? in out in out load 1 c v v 1 v v i i (5) the worst-case condition occurs at vin = 2vout, shown in equation (6): 2 i i load 1 c ? (6)
MP8714 ? 17v, 10a, synchrono us, step-down converter MP8714 rev.1.0 www.monolithicpower.com 16 12/27/2016 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2016 mps. all rights reserved. for simplification, choose an input capacitor with an rms current rating greater than half of the maximum load current. the input capacitor can be electrolytic, tantalum, or ceramic. when using electrolytic or tantalum capacitors, add a small, high-quality ceramic capacitor (e.g.: 0.1 f) as close to the ic as possible. when using ceramic capacitors, ensure that they have enough capacitance to provide sufficient charge to prevent excessive voltage ripple at the input. the input voltage ripple caused by capacitance can be estimated with equation (7): load out out in in sin iv v v1 fc1v v ?? ?? ? ?? ?? ? ?? (7) selecting the output capacitor the output capacitor (c2) maintains the dc output voltage. use ceramic, tantalum, or low- esr electrolytic capacitors. for best results, use low esr capacitors to keep the output voltage ripple low. the output voltage ripple can be estimated with equation (8): out out out esr s1 in s vv 1 v1r fl v 8fc2 ?? ?? ?? ?? ? ? ?? ?? ??? ?? ?? (8) where l 1 is the inductor value, and r esr is the equivalent series resistance (esr) value of the output capacitor. for ceramic capacitors, the capacitance dominates the impedance at the switching frequency, and the capacitance causes the majority of the output voltage ripple. for simplification, the output voltage ripple can be estimated with equation (9): out out out 2 in s1 vv ? v1 v 8f l c2 ?? ??? ?? ??? ?? (9) for tantalum or electrolytic capacitors, the esr dominates the impedance at the switching frequency. for simplification, the output ripple can be approximated by equation (10): out out out esr in s1 vv ? v1r fl v ?? ???? ?? ? ?? (10) the characteristics of the output capacitor also affect the stability of the regulation system. the MP8714 can be optimized for a wide range of capacitance and esr values. pcb layout guidelines (10) efficient pcb layout is critical for stable operation. a four-layer layout is strongly recommended to achieve better thermal performance. for best results, refer to figure 7 and follow the guidelines below. 1. place the high current paths (pgnd, vin, and sw) very close to the device with short, direct, and wide traces. 2. keep the vin and gnd pads connected with large copper traces. 3. use at least two layers for the vin and gnd trace to achieve better thermal performance. 4. add several vias close to the vin and gnd pads to help with thermal dissipation. 5. place the input capacitors as close to vin and gnd as possible. 6. place the decoupling capacitor as close to vcc and gnd as possible. 7. place the external feedback resistors next to fb. 8. ensure that there is no via on the fb trace. 9. keep the switching node sw short and away from the feedback network. 10. keep the bst voltage path (bst, c5, and sw) as short as possible. note: 10) the recommended layout is based on the typical application circuit on page 18.
MP8714 ? 17v, 10a, synchrono us, step-down converter MP8714 rev.1.0 www.monolithicpower.com 17 12/27/2016 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2016 mps. all rights reserved. c2 c3 c4 r5 4 56 13 12 11 1 14 10 3 7 2 8 9 c1 l1 r2 figure 7: recommended layout design example table 2 is a design example following the application guidelines for the specifications below. table 2: design example vin 12v vout 1v i out 10a the detailed application schematics are shown in figure 8 through figure 13. the typical performance and circuit waveforms are shown in the typical performance characteristics section. for more device applications, please refer to the related evaluation board datasheets.
MP8714 ? 17v, 10a, synchrono us, step-down converter MP8714 rev.1.0 www.monolithicpower.com 18 12/27/2016 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2016 mps. all rights reserved. typical application circuits 9 5 c3 0.47 f r4 100k c1 22f r2 162k r3 51k c2 22f c2a 22f c1a 22f c1b 0.1f r5 0 c5 0.1f c2b 22f r1 80.6k l1 1.5h c6 22pf c4 22nf vin 4.5v-17v pg vout 0.9v/10a 13 7 4 3 6 14 8 12 11 10 2 1 c2c 22f en figure 8: vin = 4.5 - 17v, vout = 0.9v, i out = 10a 9 5 c3 0.47 f r4 100k c1 22f r2 120k r3 51k c2 22f c2a 22f c1a 22f c1b 0.1f r5 0 c5 0.1f c2b 22f r1 80.6k l1 1.5h c6 22pf c4 22nf vin 4.5v-17v pg vout 1v/10a 13 7 4 6 14 8 12 11 10 2 1 c2c 22f en 3 figure 9: vin = 4.5 - 17v, vout = 1v, i out = 10a figure 10: vin = 4.5 - 17v, vout = 1.2v, i out = 10a
MP8714 ? 17v, 10a, synchrono us, step-down converter MP8714 rev.1.0 www.monolithicpower.com 19 12/27/2016 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2016 mps. all rights reserved. typical application circuits (continued) 9 5 c3 0.47 f r4 100k c1 22f r2 19.1k r3 30k c2 22f c2a 22f c1a 22f c1b 0.1f r5 0 c5 0.1f c2b 22f r1 60.4k l1 2.2h c6 22pf c4 22nf vin 4.5v-17v pg vout 2.5v/10a 13 7 4 3 6 14 8 12 11 10 2 1 c2c 22f en figure 11: vin = 4.5 - 17v, vout = 2.5v, i out = 10a figure 12: vin = 6 - 17v, vout = 3.3v, i out = 10a (11) 9 5 c3 0.47 f r4 100k c1 22f r2 8.25k r3 20k c2 22f c2a 22f c1a 22f c1b 0.1f r5 0 c5 0.1f c2b 22f r1 60.4k l1 3.3h c6 33pf c4 22nf vin 8v-17v pg vout 5v/10a 13 7 4 3 6 14 8 12 11 10 2 1 c2c 22f en figure 13: vin = 8 - 17v, vout = 5v, i out = 10a (11) note : 11) based on the evaluation board test result s at 25oc ambient temperature, a lower input voltage will trigger over-temperature protection at full load.
MP8714 ? 17v, 10a, synchrono us, 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. MP8714 rev.1.0 www.monolithicpower.com 20 12/27/2016 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2016 mps. all rights reserved. package information qfn-14 (3mmx4mm)

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