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MPQ2314 high efficiency 2a, 24v, 500khz synchronous step down converter MPQ2314 rev. 1.1 www.monolithicpower.com 1 6/10/2015 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2015 mps. all rights reserved. the future of analog ic technology description the MPQ2314 is a high frequency synchronous rectified step-down switch mode converter with built in internal power mosfets. it offers a very compact solution to achieve 2a continuous output current over a wide input supply range with excellent load and line regulation. the MPQ2314 has synchronous mode operation for higher efficiency over output current load range. current mode operation provides fast transient response and eases loop stabilization. full protection features include ocp and thermal shut down. the MPQ2314 requires a minimum number of readily available standard external components and is available in a space saving 8-pin tsot23 package. features ? wide 4.5v to 24v operating input range ? 2a load current ? 120m ? /50m ? low rds(on) internal power mosfets ? low quiescent current ? high efficiency synchronous mode operation ? fixed 500khz switching frequency ? frequency sync from 200khz to 2mhz external clock ? aam power save mode ? internal soft start ? ocp protection and hiccup ? thermal shutdown ? output adjustable from 0.8v ? available in an 8-pin tsot-23 package applications ? notebook systems and i/o power ? digital set top boxes ? flat panel television and monitors all mps parts are lead-free, halogen free, and adhere to the rohs directive. for mps green status, pl ease visit mps website under qualit y assurance. ?mps? and ?the future of analog ic technology? are registered trademarks of monolithic power systems, inc. typical application
MPQ2314 ? 24v, 2a sync step down converter MPQ2314 rev. 1.1 www.monolithicpower.com 2 6/10/2015 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2015 mps. all rights reserved. ordering information part number* package top marking MPQ2314gj tsot23-8 see blow * for tape & reel, add suffix ?z (e.g. MPQ2314gj?z); top marking aely ael: product code of MPQ2314gj; y: year code; package reference aam in sw gnd fb vcc en/sync bst 1 2 3 4 8 7 6 5 top view tsot23-8
MPQ2314 ? 24v, 2a sync step down converter MPQ2314 rev. 1.1 www.monolithicpower.com 3 6/10/2015 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2015 mps. all rights reserved. absolute maxi mum ratings (1) v in ................................................?0.3v to +28v v sw ...... ?0.3v (-5v<10ns) to +28v ( 30v <10ns) v bst ........................................................ v sw +6v all other pins ..................................-0.3v to +6v continuous power dissipation (ta=+25c) (2) ... ................................................................. 1.25w junction temperature ...............................150c lead temperature ....................................260c storage temperature................. -65c to 150c recommended operating conditions (3) supply voltage v in ............................. 4.5 to 24v output voltage v out .......................0.8v to v in *d operating junction temp (t j ).. -40c to +125c thermal resistance (4) ja jc tsot23-8 ???????...?? 100?..55..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.
MPQ2314 ? 24v, 2a sync step down converter MPQ2314 rev. 1.1 www.monolithicpower.com 4 6/10/2015 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2015 mps. all rights reserved. electrical characteristics (5) v in = 12v, t j = -40c to +125c, unless otherwise noted. typical values are at t j = +25c. parameter symbol condition min typ max units v en =0v,t j =+25c 0.03 1 a supply current(shutdown) i in v en =0v 5 a supply current(quiescent) iq v en =2v, v fb =1v, aam=0.5v 130 180 240 a hs switch on resistance hs rds-on v bst - sw =5v 120 m ? ls switch on resistance ls rds-on v cc =5v 50 m ? switch leakage swlkg v en= 0v, v sw =12v 0.01 1 a current limit i lmit duty cycle=40% 3 4 a v fb =750mv, t j =+25c 420 500 620 khz oscillator frequency fsw v fb =750mv 380 620 khz fold-back frequency f fb v fb =200mv 0.5 fsw maximum duty cycle d max v fb =750mv 90 95 % minimum on time (5) t on_min 60 ns sync frequency range f sync 0.2 2 mhz t j =+25c 0.779 0.791 0.803 v feedback voltage v fb 0.775 0.807 v feedback current i fb v fb =820mv 10 50 na t j =+25c 1.2 1.4 1.6 v en rising threshold v en_rising 1.1 1.7 v t j =+25c 1.1 1.25 1.4 en falling threshold v en_faling 1 1.5 en hysteresis v en_hys 150 mv t j =25c 1.5 2 2.5 v en =2v t j =-40c to 125c 1.2 2.8 a en input current i en v en =0 5 50 na en turn off delay entd-off 6 10 14 us t j =+25c 3.7 3.9 4.1 v vin under voltage lockout threshold-rising inuvrising 3.6 4.2 v
MPQ2314 ? 24v, 2a sync step down converter MPQ2314 rev. 1.1 www.monolithicpower.com 5 6/10/2015 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2015 mps. all rights reserved. electrical characteristics (5) v in = 12v, t j = -40c to +125c, unless otherwise noted. typical values are at t j = +25c. parameter symbol condition min typ max units t j =+25c 2.9 3.2 3.5 v vin under voltage lockout threshold-falling inuvfalling 2.8 3.6 v vin under voltage lockout threshold- hysteresis inuvhys 650 mv vcc regulation v cc i cc =0 to 5ma 4.6 4.9 5.15 v vcc load regulation i cc =0 to 5ma 1 3 % v out from 10% to 90%, t j =+25c 0.8 1.5 2.2 ms soft-start period t ss v out from 10% to 90% 0.5 2.6 ms thermal shutdown (5) 150 c thermal hysteresis (5) 20 c t j =+25c 5.6 6.2 6.8 a aam source current i aam 4 8 a notes: 5) derived from bench characte rization. not tested in production.
MPQ2314 ? 24v, 2a sync step down converter MPQ2314 rev. 1.1 www.monolithicpower.com 6 6/10/2015 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2015 mps. all rights reserved. typical characteristics
MPQ2314 ? 24v, 2a sync step down converter MPQ2314 rev. 1.1 www.monolithicpower.com 7 6/10/2015 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2015 mps. all rights reserved. typical characteristics (continued)
MPQ2314 ? 24v, 2a sync step down converter MPQ2314 rev. 1.1 www.monolithicpower.com 8 6/10/2015 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2015 mps. all rights reserved. typical characteristics (continued)
MPQ2314 ? 24v, 2a sync step down converter MPQ2314 rev. 1.1 www.monolithicpower.com 9 6/10/2015 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2015 mps. all rights reserved. typical performanc e characteristics v in = 19v, v out = 5v, l = 6.5uh, t a = 25c, unless otherwise noted. v out /ac 20mv/div. v in /ac 200mv/div. v sw 10v/div. i l 2a/div. v out /ac 20mv/div. v in /ac 500mv/div. v sw 10v/div. i l 1a/div. v out 2v/div. v in 10v/div. v sw 10v/div. i l 1a/div. v out 2v/div. v in 10v/div. v sw 10v/div. i l 2a/div. v out 2v/div. v en 5v/div. v sw 10v/div. i l 2a/div. v out 2v/div. v en 5v/div. v sw 10v/div. i l 5a/div. v out 2v/div. v en 5v/div. v sw 10v/div. i l 2a/div. v out 2v/div. v in 10v/div. v sw 10v/div. i l 2a/div. v out 2v/div. v in 10v/div. v sw 10v/div. i l 1a/div.
MPQ2314 ? 24v, 2a sync step down converter MPQ2314 rev. 1.1 www.monolithicpower.com 10 6/10/2015 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2015 mps. all rights reserved. typical performanc e characteristics (continued) v in = 19v, v out = 5v, l = 6.5h, t a = 25c, unless otherwise noted. v out /ac 50mv/div. i o 1a/div. v out 2v/div. v en 5v/div. v sw 10v/div. i l 1a/div.
MPQ2314 ? 24v, 2a sync step down converter MPQ2314 rev. 1.1 www.monolithicpower.com 11 6/10/2015 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2015 mps. all rights reserved. pin functions package pin # name description 1 aam a resistor is connected from aam pin to ground to set a aam voltage force MPQ2314 into non-synchronous mode when load is small. drive aam pin high (=vcc) will force MPQ2314 into ccm. 2 in supply voltage. the MPQ2314 operates from a +4.5v to +24v input rail. c1 is needed to decouple the input rail. use wide pcb trace to make the connection. 3 sw switch output. use wide pc b trace to make the connection. 4 gnd system ground. this pin is the referenc e ground 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. 5 bst bootstrap. a capacitor and a 20 ? resistor connected between sw and bst pins are required to form a floating supply across the high-side switch driver. 6 en/sync en=1 to enable the MPQ2314. external clock can be applied to en pin for changing switching frequency. 7 vcc bias supply. decouple with 0.1 f-0.22 f cap. and the capacitance should be no more than 0.22 f 8 fb feedback. an external resistor divider from the output to gnd, tapped to the fb pin, sets the output voltage. to prevent current limit r un away during a short circuit fault condition the frequency fold-back comparator lowers th e oscillator frequency when the fb voltage is below 400mv.
MPQ2314 ? 24v, 2a sync step down converter MPQ2314 rev. 1.1 www.monolithicpower.com 12 6/10/2015 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2015 mps. all rights reserved. function block diagram figure 1: functional block diagram
MPQ2314 ? 24v, 2a sync step down converter MPQ2314 rev. 1.1 www.monolithicpower.com 13 6/10/2015 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2015 mps. all rights reserved. operation the MPQ2314 is a high frequency synchronous rectified step-down switch mode converter with built in internal power mosfets. it offers a very compact solution to achieve 2a continuous output current over a wide input supply range with excellent load and line regulation. the MPQ2314 operates in a fixed frequency, peak current control mode to regulate the output voltage. a pwm cycle is initiated by the internal clock. the integrated high-side power mosfet is turned on and remains on until its current reaches the value set by the comp voltage. when the power switch is off, it remains off until the next clock cycle starts. if, in 95% of one pwm period, the current in the power mosfet does not reach the comp set current value, the power mosfet will be forced to turn off. internal regulator most of the internal circuitries are powered from the 5v internal regulator. 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 decreases, a 0.1uf ceramic capacitor for decoupling purpose is required. error amplifier the error amplifier compares the fb pin voltage with the internal 0.8v reference (ref) and outputs a comp voltage, which is used to control the power mosfet current. the optimized internal compensation network minimizes the external component counts and simplifies the control loop design. aam operation the MPQ2314 has aam (advanced asynchronous modulation) power-save mode for light load. connect a resistor from aam pin to gnd to set aam voltage. under the heavy load condition, the v comp is higher than v aam . when the clock goes high, the high-side power mosfet turns on and remains on until v ilsense reaches the value set by the comp voltage. the internal clock resets every time when v comp is higher than v aam . under the light load condition, the value of v comp is low. when v comp is less than v aam and v fb is less than v ref , v comp ramps up until it exceeds v aam . during this time, the internal clock is blocked, thus the MPQ2314 skips some pulses for pfm (pulse frequency modulation) mode and achieves the light load power save. clock r1 r2 1.1pf 50pf 400k 20k q s r figure 2: simplified aam control logic enable/sync control en is a digital control pin that turns the regulator on and off. drive en high to turn on the regulator, drive it low to turn it off. there is an internal 1meg resistor from en to gnd thus en can be floated to shut down the chip. also en pin voltage was clamped to around 6.5v by an internal zener-diode. please use large enough pull up resistor connecting between vin and en to limit the en input current which should be less than 100ua. generally, around 100k resistor should be large enough for all the applications. the chip can be synchronized to external clock range from 200khz up to 2mhz through this pin 2ms right after output voltage is set, with the internal clock rising edge synchronized to the external clock rising edge. en synchronize logic high voltage should higher than 2v. en synchronize logic low voltage should lower than 400mv. en logic high pulse width must less than 1.6s. otherwise the internal clock may come and turn on high side mosfet again. en logic low pulse width must less than 6s, otherwise MPQ2314 may en shutdown.
MPQ2314 ? 24v, 2a sync step down converter MPQ2314 rev. 1.1 www.monolithicpower.com 14 6/10/2015 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2015 mps. all rights reserved. under-voltage lockout (uvlo) under-voltage lockout (uvlo) is implemented to protect the chip from operating at insufficient supply voltage. the MPQ2314 uvlo comparator monitors the output voltage of the internal regulator, vcc. the uvlo rising threshold is about 3.9v while its falling threshold is consistent 3.25v. internal soft-start the soft start is implemented to prevent the converter output voltage from overshooting during start up. when the chip starts, the internal circuitry generates a soft-start voltage (ss) ramping up from 0v. 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. the soft- start time is internally set to be around 1.5ms. over-current-protection and hiccup the MPQ2314 has cycle-by-cycle over current limit when the inductor current peak value exceeds the set current limit threshold. meanwhile, output voltage starts to drop until fb is below the under-voltage (uv) threshold, typically 50% below the reference. once a uv is triggered, the MPQ2314 enters hiccup mode to periodically restart the part. this protection mode is especially useful when the output is dead-short to ground. the average short circuit current is greatly reduced to alleviate the thermal issue and to protect the regulator. the MPQ2314 exits the hicc up mode once the over current condition is removed. thermal shutdown thermal shutdown is implemented to prevent the chip from operating at exceedingly high temperatures. when the silicon die temperature is higher than 150c, it shuts down the whole chip. when the temperature is lower than its lower threshold, typically 130c, the chip is enabled again. floating driver and bootstrap charging the floating power mosfet driver is powered by an external bootstrap capacitor. 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, r5, c5, l1 and c2 (figure 3). if (vin-vsw) is more than 5v, u2 will regulate m3 to maintain a 5v bst voltage across c5. figure 3: internal bootstrap charging circuit startup and shutdown if both v in and en are higher than their appropriate thresholds, the chip starts. the reference block starts first, generating stable reference voltage and currents, and then the internal regulator is enabled. the regulator provides stable supply for the remaining circuitries. three events can shut down the chip: en low, vin low and thermal shutdown. in the shutdown procedure, the signaling path is first blocked to avoid any fault triggering. the comp voltage and the internal supply rail are then pulled down. the floating driver is not subject to this shutdown command.
MPQ2314 ? 24v, 2a sync step down converter MPQ2314 rev. 1.1 www.monolithicpower.com 15 6/10/2015 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2015 mps. all rights reserved. application information component selection setting the output voltage the external resistor divider is used to set the output voltage (see typical application on page 1). the feedback resistor r1 also sets the feedback loop bandwidth with the internal compensation capacitor (see typical application on page 1). r2 is then given by: out r1 r2 v 1 0.8v ? ? the t-type network is highly recommended, as figure 4 shows. fb 8 rt r2 r1 vout figure 4: t-type network table 1 lists the recommended t-type resistors value for common output voltages. table 1?resistor selection for common output voltages v out (v) r1 (k ? ) r2 (k ? ) rt (k ? ) lo (h) co(f) 1.05 20.5 62 100 1.8 44 1.2 20.5 39.2 75 2.2 44 1.8 40.2 31.6 59 3.3 44 2.5 40.2 18.7 40.2 4.2 44 3.3 40.2 12.7 33 4.7 44 5 40.2 7.5 20 6.5 44 selecting the inductor a 1h to 10h inductor with a dc current rating of at least 25% percent higher than the maximum load current is recommended for most applications. for highest efficiency, the inductor dc resistance should be less than 15m ? . for most designs, the inductance value can be derived from the following equation. out in out 1 in l osc v(vv) l vif ?? ? ?? ? where i l is the inductor ripple current. choose inductor current to be approximately 30% of the maximum load current. 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. setting the aam voltage the aam voltage is used to setting the transition point from aam to ccm. it should be chosen to provide the best combination of efficiency, stability, ripple, and transient. if the aam voltage is set lower, then stability and ripple improves, but efficiency during aam mode and transient degrades. likewise, if the aam voltage is set higher, then the efficiency during aam and transient improves, but stability and ripple degrades. so the optimal balance point of aam voltage for good efficiency, stability, ripple and transient should be found out. adjust the aam threshold by connecting a resistor from aam pin to ground. take figure 5 as reference. an internal 6.2a current source charges the external resistor. figure 5: aam network generally, r4 is then given by: v aam =r4 x 6.2ua the optimized aam can be got from figure 6.
MPQ2314 ? 24v, 2a sync step down converter MPQ2314 rev. 1.1 www.monolithicpower.com 16 6/10/2015 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2015 mps. all rights reserved. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 02468 figure 6: aam selection for common output voltages (v in =4.5v-24v) selecting the input capacitor the input current to the step-down converter is discontinuous, therefore a capacitor is required to supply the 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 highly recommended because of their low esr and small temperature coefficients. for most applications, a 22f capacitor is sufficient. since the input capacitor (c1) absorbs the input switching current it requires an adequate ripple current rating. the rms current in the input capacitor can be estimated by: ? ? ? ? ? ? ? ? ? ? ? ? in out in out load 1 c v v 1 v v i i the worse case condition occurs at vin = 2vout, where: 2 i i load 1 c ? for simplification, choose the input capacitor whose 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, a small, high quality ceramic capacitor, i.e. 0.1 f, should be placed as close to the ic as possible. when using ceramic capacitors, make sure that they have enough capacitance to provide sufficient charge to prevent excessive voltage ripple at input. the input voltage ripple caused by capacitance can be estimated by: load out out in in sin iv v v1 fc1v v ?? ?? ? ?? ?? ? ?? selecting the output capacitor the output capacitor (c2) is required to maintain the dc output voltage. ceramic, tantalum, or low esr electrolytic capacitors are recommended. low esr capacitors are preferred to keep the output voltage ripple low. the output voltage ripple can be estimated by: out out out esr s1 in s vv 1 v1r fl v 8fc2 ?? ?? ?? ?? ? ? ?? ?? ??? ?? ?? where l 1 is the inductor value and resr is the equivalent series resistance (esr) value of the output capacitor. in the case of ceramic capacitors, the impedance at the switching frequency is dominated by the capacitance. the output voltage ripple is mainly caused by the capacitance. for simplification, the output voltage ripple can be estimated by: out out out 2 in s1 vv v1 v 8f l c2 ?? ??? ?? ??? ?? in the case of tantalum or electrolytic capacitors, the esr dominates the impedance at the switching frequency. for simplification, the output ripple can be approximated to: out out out esr in s1 vv v1r fl v ?? ???? ?? ? ?? the characteristics of the output capacitor also affect the stability of the regulation system. the MPQ2314 can be optimized for a wide range of capacitance and esr values. external bootstrap diode an external bootstrap diode may enhance the efficiency of the regulator, the applicable conditions of external bst diode are: ? v out is 5v or 3.3v; and ? duty cycle is high: d= in out v v >65%
MPQ2314 ? 24v, 2a sync step down converter MPQ2314 rev. 1.1 www.monolithicpower.com 17 6/10/2015 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2015 mps. all rights reserved. in these cases, an external bst diode is recommended from the vcc pin to bst pin, as shown in figure 7. figure 7: add optional external bootstrap diode to enhance efficiency the recommended external bst diode is in4148, and the bst cap is 0.1 1 f. pc board layout (6) pcb layout is very important to achieve stable operation. please follow these guidelines and take figure 8 as reference. 1) keep the connection of input ground and gnd pin as short and wide as possible. 2) keep the connection of input capacitor and in pin as short and wide as possible. 3) ensure all feedback connections are short and direct. place the feedback resistors and compensation components as close to the chip as possible. 4) route sw away from sensitive analog areas such as fb. notes: 6) the recommended layout is based on the figure 9 typical application circuit on the next page. 8 7 6 l1 c2 c2a c1 r6 r7 r8 r9 r4 r1 r2 r3 r5 c3 c5 c6 c4 1 2 3 4 vin gnd vout sw gnd 5 8 c c 1 a sw bst en / sync vcc gnd gnd vout figure 8: sample board layout
MPQ2314 ? 24v, 2a sync step down converter MPQ2314 rev. 1.1 www.monolithicpower.com 18 6/10/2015 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2015 mps. all rights reserved. design example below is a design example following the application guidelines for the specifications: table 2: design example v in 19v v out 5v i o 2a the detailed application schematics are shown in figures 9 through 14. the typical performance and circuit waveforms have been shown in the typical performance characteristics section. for more device applications, please refer to the related evaluation board datasheets.
MPQ2314 ? 24v, 2a sync step down converter MPQ2314 rev. 1.1 www.monolithicpower.com 19 6/10/2015 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2015 mps. all rights reserved. typical application circuits figure 9: vo=5v, io=2a figure 10: vo=3.3v, io=2a figure 11: vo=2.5v, io=2a
MPQ2314 ? 24v, 2a sync step down converter MPQ2314 rev. 1.1 www.monolithicpower.com 20 6/10/2015 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2015 mps. all rights reserved. figure 12: vo=1.8v, io=2a figure 13: vo=1.2v, io=2a figure 14: vo=1.05v, io=2a
MPQ2314 ? 24v, 2a sync 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. MPQ2314 rev. 1.1 www.monolithicpower.com 21 6/10/2015 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2015 mps. all rights reserved. package information tsot23-8

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