View MPQ4558DN_7310442.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

mpq4558 1a, 2mhz, 55v step-down converter aec-q100 qualified mpq4558 rev. 1.01 www.monolithicpower.com 1 5/17/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. the future of analog ic technology description the mpq4558 is a high-frequency, step-down switching regulator with an integrated internal high-side high-voltage power mosfet. it provides up to a 1a output with current-mode control for fast loop response and easy compensation. the wide 3.8v-to-55v input range accommodates a variety of step-down applications, including automotive input. a 12a shutdown-mode supply current makes it suitable for battery-powered applications. a scaled-down switching frequency in light-load conditions provides high power-conversion efficiency over a wide load range while reducing switching and gate driver losses. the frequency fold-back prevents inductor current runaway during startup and thermal shutdown provides reliable, fault-tolerant operation. by switching at 2mhz, the mpq4558 can prevent emi (electromagnetic interference) noise problems, such as those found in am radio and adsl applications. the mpq4558 is available in an soic8e and a 10-pin 3mm x 3mm qfn package. features ? guaranteed industrial/automotive temperature range limits ? wide 3.8v-to-55v operating input range ? 250m ? internal power mosfet ? up to 2mhz programmable switching frequency ? 140 a quiescent current ? stable with ceramic capacitors ? internal soft-start ? up to 95% efficiency ? output adjustable from 0.8v to 52v ? available in soic8e and 3mm x 3mm qfn10 packages ? available in aec-q100 grade 1 applications ? high-voltage power conversion ? automotive systems ? industrial power systems ? distributed power systems ? battery powered systems all mps parts are lead-free and adhere to the rohs directive. for mps green status, please visit mps website unde r products, quality assurance page. ?mps? and ?the future of analog ic technology? are registered trademarks of monolithic power systems, inc. typical application mpq4558 comp fb freq en vin gnd sw bst v out 3.3v @ 1a v in 8v to 55v control c1 c4 680pf d1 c3 100nf c2 l1 r1 127k r2 40.2k r3 200k r4 24k efficiency (%) 0 0.5 0.75 0.25 1 output current (a) efficiency @v out =3.3v fs=500khz v in =12v v in =55v 100 90 80 70 60 50 40 30 20 10 0
mpq4558 ? 1a, 2mhz, 55v step-down converter, aec-q100 qualified mpq4558 rev. 1.01 www.monolithicpower.com 2 5/17/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. ordering information part number package top marking junction temperature (t j ) MPQ4558DN * soic8e mp4558dn mpq4558dq ** qfn10 (3 x 3mm) abp mpq4558dq-aec1*** qfn10 (3 x 3mm) abp -40c to +125c * for tape & reel, add suffix ?z (e.g. MPQ4558DN?z) for rohs compliant packaging, add suffix ?lf, (e.g. MPQ4558DN?lf?z) ** for tape & reel, add suffix ?z (e.g. mpq4558dq?z) for rohs compliant packaging, add suffix ?lf, (e.g. mpq4558dq?lf?z) ***available end sept. 2011 package reference sw en comp fb bst vin freq gnd 1 2 3 4 8 7 6 5 top view exposed pad top view sw sw en comp fb 1 2 3 4 5 bst vin vin freq gnd 10 9 8 7 6 exposed pad on backside soic8e qfn10 (3mm x 3mm) absolute maxi mum ratings (1) supply voltage (v in ).....................?0.3v to +60v switch voltage (v sw )..........?0.5v to (v in + 0.5v) bst to sw .....................................?0.3v to +5v all other pins .................................?0.3v to +5v continuous power dissipation (t j = +25c) (2) soic8e???????????????.2.5w qfn10???????????????. 2.5w junction temperature ...............................150c lead temperature ....................................260c storage temperature.............. ?65c to +150c recommended operating conditions (3) supply voltage v in ...........................3.8v to 55v output voltage v out .........................0.8v to 52v maximum junction temp. (t j ) ................ 125c thermal resistance (4) ja jc soic8e ...................................50 ...... 10 ... c/w 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 ta. 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 power 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 board.
mpq4558 ? 1a, 2mhz, 55v step-down converter, aec-q100 qualified mpq4558 rev. 1.01 www.monolithicpower.com 3 5/17/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. electrical characteristics v in = 12v, v en = 2.5v, v comp = 1.4v, t j = ?40c to +125c. typical values are at t j =25c, unless otherwise noted. parameter symbol condition min typ max units t j =25c 0.780 0.800 0.820 -40c t j 85c 0.772 0.829 v feedback voltage v fb 4.5v < v in < 55v -40c t j 125c 0.766 0.829 feedback leakage current i fb 0.1 1.0 a t j =25c 175 250 330 upper switch on resistance (5) r ds(on) v bst ? v sw = 5v 160 400 m ? upper switch leakage i sw v en = 0v, v sw = 0v 1 a t j =25c 1.3 1.9 3.5 current limit i lim duty cycle 60% 1.1 3.7 a comp to current sense transconductance g cs 5.7 a/v error amp voltage gain 400 v/v error amp transconductance i comp = 3a 120 a/v error amp min source current v fb = 0.7v 10 a error amp min sink current v fb = 0.9v -10 a t j =25c 2.7 3.0 3.3 v vin uvlo threshold 2.4 3.6 vin uvlo hysteresis 0.35 v soft-start time (5) 0v < v fb < 0.8v 0.19 0.5 ms t j =25c 0.8 1 1.2 mhz oscillator frequency f sw r freq = 95k ? 0.7 1.3 shutdown supply current i s v en < 0.3v 12 20 a quiescent supply current i q no load, v fb = 0.9v (no switching) 140 200 a thermal shutdown hysteresis = 20c 150 c minimum off time t off 100 ns minimum on time (5) t on 100 ns t j =25c 1.4 1.55 1.7 v en rising threshold 1.3 1.8 en threshold hysteresis 320 mv notes: 5) derived from bench characteri zation. not tested in production..
mpq4558 ? 1a, 2mhz, 55v step-down converter, aec-q100 qualified mpq4558 rev. 1.01 www.monolithicpower.com 4 5/17/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. pin functions soic8 pin # qfn10 pin# name description 1 1, 2 sw switch node. output of the high-side switch. requires a low v f schottky rectifier to ground. place the rectifier close to the sw pins to reduce switching spikes. 2 3 en enable input. pull this pin below the specifi ed threshold to shut the chip down. pull it above the specified threshold or le aving it floating to enable the chip. 3 4 comp compensation. gm error amplifier output. apply control-loop frequency compensation to this pin. 4 5 fb feedback. input to the error amplifier. connect an external resistive divider between the output and gnd: compare to the internal +0.8v reference to set the regulation voltage. 5 6 gnd, exposed pad ground. connect as close as possible to the output capacitor and avoid high- current switching paths. connect the exposed pad to gnd plane for optimal thermal performance. 6 7 freq switching frequency program input. connect a resistor from this pin to ground to set the switching frequency. 7 8, 9 vin input supply. supplies power to all t he internal control circuitry, both bs regulators, and the high-side switch. pl ace a decoupling capacitor to ground close to this pin to minimize switching spikes. 8 10 bst bootstrap. positive power supply for the in ternal floating high-side mosfet driver. connect a bypass capacitor between this pin and the sw pin.
mpq4558 ? 1a, 2mhz, 55v step-down converter, aec-q100 qualified mpq4558 rev. 1.01 www.monolithicpower.com 5 5/17/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. typical characteristics vin shut-down voltage(v) vin start-up voltage(v) i peak_limit (a) duty cycle vin shut-down vs. junction temperature voltage reference vs. junction temperature vin start-up vs. junction temperature venable-low vs. junction temperature venable-high vs. junction temperature ven low voltage(v) ven high voltage(v) on resistance vs. junction temperature i peak_limit (a) voltage reference (v) switching frequency (khz) 150 200 250 300 350 400 450 500 -50 -25 0 25 50 75 100 125 1.0 1.2 1.4 1.6 1.8 2.0 2.2 0% 20% 40% 60% 80% 1.0 1.2 1.4 1.6 1.8 2.0 2.2 -50 -25 0 25 50 75 100 125 2.90 2.95 3.00 3.05 3.10 3.15 3.20 3.25 -50 -25 0 25 50 75 100 125 2.55 2.58 2.61 2.64 2.67 2.70 2.73 -50 -25 0 25 50 75 100 125 0.780 0.785 0.790 0.795 0.800 0.805 0.810 -50 -25 0 25 50 75 100 125 1.30 1.35 1.40 1.45 1.50 1.55 1.60 1.65 1.70 1.75 -50 -25 0 25 50 75 100 125 1.21 1.22 1.23 1.24 1.25 1.26 -50 -25 0 25 50 75 100 125 480 485 490 495 500 505 510 -50 -25 0 25 50 75 100 125
mpq4558 ? 1a, 2mhz, 55v step-down converter, aec-q100 qualified mpq4558 rev. 1.01 www.monolithicpower.com 6 5/17/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. typical characteristics (continued) input voltage(v) switching frequency (khz) feedback voltage(v) shutdown current vs. junction temperature v in =12v vin quiescent current vs. junction temperature v in =12v input voltage(v) switching frequency (khz) frequency vs. freq resistor 0 500 1000 1500 2000 0 100 200 300 400 500 0 100 200 300 400 500 600 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 100 110 120 130 140 150 160 170 0 102030405060 100 110 120 130 140 150 160 170 -50 -25 0 25 50 75 100 125 6 8 10 12 14 16 18 0102030405060 0 5 10 15 20 -50 -25 0 25 50 75 100 125
mpq4558 ? 1a, 2mhz, 55v step-down converter, aec-q100 qualified mpq4558 rev. 1.01 www.monolithicpower.com 7 5/17/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. typical performanc e characteristics v in = 12v, v out =3.3v, c1 = 4.7f, c2 = 22f, l1 = 10h and t j = 25c, unless otherwise noted. 0 10 20 30 40 50 60 70 80 90 100 efficiency ( ) efficiency ( ) output current (a) output current (a) efficiency @v out =5v output voltage ripple i out =0.1a v out ac coupled 10mv/div v sw 10v/div i l 500ma/div output voltage ripple i out =1a v out ac coupled 10mv/div v sw 10v/div i l 1a/div 0 10 20 30 40 50 60 70 80 90 0 0.5 0.25 0.75 1 v in =12v v in =12v v in =55v v in =48v 0 0.5 0.25 0.75 1 v en 2v/div v out 2v/div v sw 10v/div i l 1a/div i out =0.1a i out =1a v en 2v/div v out 2v/div v sw 10v/div i l 1a/div start up start up shut down i out =0.1a en 2v/div out 2v/div sw 10v/div i l 1a/div shut down i out =1a v en 2v/div v out 2v/div v sw 10v/div i l 1a/div short circuit entry i out =0.1a to short out 2v/div sw 10v/div i l 1a/div
mpq4558 ? 1a, 2mhz, 55v step-down converter, aec-q100 qualified mpq4558 rev. 1.01 www.monolithicpower.com 8 5/17/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. typical performanc e characteristics (continued) v in = 12v, v out =3.3v, c1 = 4.7f, c2 = 22f, l1 = 10h and t j = 25c, unless otherwise noted. v out 2v/div v sw 10v/div i l 1a/div short circuit steady state short circuit recovery i out =short to 0a v out 2v/div v sw 10v/div i l 2a/div
mpq4558 ? 1a, 2mhz, 55v step-down converter, aec-q100 qualified mpq4558 rev. 1.01 www.monolithicpower.com 9 5/17/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. block diagram -- + logic -- + 0.5ms ss ss comp isw vin bst sw freq gnd comp fb en ss 0v8 reference uvlo internal regulators oscillator figure 1: functional block diagram operation the mpq4558 is a programmable-frequency, non-synchronous, step-down, switching regulator with an integrated high-side, high-voltage power mosfet. it provides a single, highly efficient solution with current-mode control for fast loop response and easy compensation. it features a wide input voltage range, internal soft-start control, and precision current limiting. its very low operational quiescent current makes it suitable for battery-powered applications. pwm control mode at moderate-to-high output current, the mpq4558 operates in a fixed-frequency, peak- current?control mode to regulate the output voltage. the internal clock initiates a pwm cycle. the power mosfet turns on and remains on until its current reaches the value set by the comp voltage. when the power mosfet is off, it remains off for at least 100ns before the next cycle starts. if, in one pwm period, the power mosfet current does not reach the comp set current value, the power mosfet remains on to saves on a turn-off operation. pulse-skipping mode under light-load condition, the switching frequency drops to zero to reduce switching and driving losses. error amplifier the error amplifier compares the fb pin voltage with the internal reference (ref) and outputs a current proportional to the difference between the two. this output current then charges the external compensation network to form the comp voltage, which controls the power mosfet current. while in operation, the minimum comp voltage is clamped to 0.9v and its maximum is clamped to 2.0v. comp is internally pulled down to gnd in shutdown mode. avoid pulling comp up beyond 2.6v.
mpq4558 ? 1a, 2mhz, 55v step-down converter, aec-q100 qualified mpq4558 rev. 1.01 www.monolithicpower.com 10 5/17/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. internal regulator the 2.6v internal regulator powers most of the internal circuits. this regulator takes the vin input and operates in the full vin range. when v in exceeds 3.0v, the output of the regulator is in full regulation: when v in is less than 3.0v, the output drops to 0v. enable control the mpq4558 has a dedicated enable control pin (en): an input voltage that exceeds an upper threshold enables the chip, while a voltage the drops below a lower threshold disables the chip. its falling threshold is precisely 1.2v, and its rising threshold is 300mv higher, or 1.5v. when floating, en is pulled up to about 3.0v by an internal 1a current source to enable the chip. pulling it down requires a 1a current. when en drops below 1.2v, the chip enters the lowest shutdown current mode. when en exceeds 0v but remains below its rising threshold, the chip is still in shutdown mode but with a slightly higher shutdown current. under-voltage lockout under-voltage lockout (uvlo) protects the chip from operating at an insufficient supply voltage. the uvlo rising threshold is about 3.0v while its falling threshold is a consistent 2.6v. internal soft-start soft-start prevents the converter output voltage from overshooting during start-up and short- circuit recovery. when the chip starts, the internal circuitry generates a soft-start (ss) voltage that ramps up from 0v to 2.6v. when this voltage is less than the internal reference (ref), ss overrides ref so the error amplifier uses ss as the reference. when ss exceeds ref, ref regains control. thermal shutdown thermal shutdown prevents the chip from operating at exceedingly high temperatures. when the silicon die temperature exceeds its upper threshold, it shuts down the whole chip. when the temperature falls below its lower threshold, 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 with a rising threshold of 2.2v and a hysteresis of 150mv. the driver?s uvlo is connected to the ss: if the bootstrap voltage hits its uvlo, the soft-start circuit resets. to prevent noise, there is 20s delay before the reset action. when the device exits the bootstrap uvlo condition, the reset turns off and then soft-start process resumes. the dedicated internal bootstrap regulator charges and regulates the bootstrap capacitor to about 5v. when the voltage between the bst and sw nodes falls below regulation, a pmos pass transistor connected from vin to bst turns on. the charging current path goes from vin, to bst and then to sw. the external circuit must provide enough voltage headroom to facilitate charging. as long as v in is sufficiently higher than sw, the bootstrap capacitor will charge. when the power mosfet is on, v in is about equal to sw so the bootstrap capacitor cannot charge. when the external diode is on, the difference between vin and sw is at its largest, thus making it the best period to charge. when there is no current in the inductor, sw equals the output voltage v out so the difference between v in and v out can charge the bootstrap capacitor. under higher duty-cycle operation conditions, the time period available for bootstrap charging is smaller so the bootstrap capacitor may not sufficiently charge. in case the internal circuit does not have sufficient voltage and the bootstrap capacitor is not charged, extra external circuitry can ensure the bootstrap voltage is in the normal operational region. refer to the external bootstrap diode in application section. the dc quiescent current of the floating driver is about 20a. make sure the bleeding current at the sw node is higher than this value, such that: a 20 ) 2 r 1 r ( v i o o > + +
mpq4558 ? 1a, 2mhz, 55v step-down converter, aec-q100 qualified mpq4558 rev. 1.01 www.monolithicpower.com 11 5/17/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. current comparator and current limit a current-sense mosfet accurately senses the current in the power mosfet. this signal is then fed to the high speed current comparator for current-mode?control purposes, which uses it as one of its inputs with the comp voltage. when the power mosfet turns on, the comparator is first blanked until the end of the turn-on transition to avoid noise issues. when the sensed current exceeds the comp voltage, the comparator output is low and the power mosfet turns off. the cycle-by-cycle maximum current of the internal power mosfet is internally limited. short-circuit protection when the output is shorted to the ground, the switching frequency folds back and the current limit falls to reduce the short circuit current. when the fb voltage equals 0v, the current limit falls to about 50% of its full current limit. the fb voltage reaches its 100% of its current limit when it exceeds 0.4v when the short-circuit fb voltage is low, the ss drops by v fb and ss v fb + 100mv. if the short circuit is removed, the output voltage recovers at the ss rate. when fb is high enough, the frequency and current limit return to normal values. startup and shutdown if both v in and v en exceed 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. while the internal supply rail is up, an internal timer blanks the power mosfet off for about 50s to avoid start-up glitches. when the internal soft-start block is enabled, it first holds its ss output low to ensure the other circuits are ready and then slowly ramps up. three events can shut down the chip: en low, v in low and thermal shutdown. in shutdown, the power mosfet turns off first to avoid any fault triggering. the comp voltage and the internal supply rail are then pulled down. programmable oscillator an external resistor?r freq connected from the freq pin to gnd?sets the mpq4558 oscillating frequency. calculate the value of r freq from: freq s 100000 r(k ? )= -5 f(khz) for f sw =500khz, r freq =195k ? .
mpq4558 ? 1a, 2mhz, 55v step-down converter, aec-q100 qualified mpq4558 rev. 1.01 www.monolithicpower.com 12 5/17/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. application information component selection setting the output voltage set the output voltage with a resistor divider between the output voltage and the fb pin. the voltage divider drops the output voltage down to the feedback voltage by the ratio: fb out r2 v=v r1+r2 thus the output voltage is: out fb r1+r2 v=v r2 for example, for r2 = 10k ? , r1 can be determined by: ) )( 8 . 0 ? = k (v 12.5 r1 out for example, for a 3.3v output voltage, r2 is 10k ? , and r1 is 31.6k ? . inductor the inductor supplies constant current to the output load while being driven by the switched input voltage. a larger value inductor will result in less ripple current that will lower the output ripple voltage. however, a larger-valued inductor is physically larger, has a higher series resistance, or lower saturation current. generally, determine an appropriate inductance value by selecting the peak-to-peak inductor ripple current equal to approximately 30% of the maximum switch current limit. also, make sure that the peak inductor current is below the maximum switch current limit. calculate the inductance value with: out out sl in vv l1= (1- ) f iv where: ? v out is the output voltage, ? v in is the input voltage, ? f s is the switching frequency, and ? ? i l is the peak-to-peak inductor ripple current. choose an inductor that will not saturate under the maximum inductor peak current. calculate the peak inductor current with: ? ? ? ? ? ? ? ? ? + = in out s out load lp v v 1 1 l f 2 v i i where i load is the load current. table 1 lists a number of suitable inductors from various manufacturers. the choice the inductor style mainly depends on the price vs. size requirements and any emi requirement.
mpq4558 ? 1a, 2mhz, 55v step-down converter, aec-q100 qualified mpq4558 rev. 1.01 www.monolithicpower.com 13 5/17/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. table 1: inductor selection guide part number inductance (h) max dcr ( ? ) current rating (a) dimensions l x w x h (mm) wurth electronics 7447789004 4.7 0.033 2.9 7.3x7.3x3.2 744066100 10 0.035 3.6 10x10x3.8 744771115 15 0.025 3.75 12x12x6 744771122 22 0.031 3.37 12x12x6 tdk rlf7030t-4r7 4.7 0. 031 3.4 7.3x6.8x3.2 slf10145t-100 10 0.0364 3 10.1x10.1x4.5 slf12565t-150m4r2 15 0.0237 4.2 12.5x12.5x6.5 slf12565t-220m3r5 22 0.0316 3.5 12.5x12.5x6.5 toko fdv0630-4r7m 4.7 0.049 3.3 7.7x7x3 919as-100m 10 0.0265 4.3 10.3x10.3x4.5 919as-160m 16 0.0492 3.3 10.3x10.3x4.5 919as-220m 22 0.0776 3 10.3x10.3x4.5 output rectifier diode the output rectifier diode supplies the current to the inductor when the high-side switch is off. to reduce losses due to the forward diode voltage and recovery times, use a schottky diode. choose a diode whose maximum reverse voltage rating is greater than the maximum input voltage, and whose current rating is greater than the maximum load current. table 2 lists example schottky diodes and manufacturers. table 2: diode selection guide diodes voltage/ current rating manufacturer b290-13-f 90v, 2a diodes inc. b380-13-f 80v, 3a diodes inc. cmsh2-100m 100v, 2a central semi cmsh3-100ma 100v, 3a central semi
mpq4558 ? 1a, 2mhz, 55v step-down converter, aec-q100 qualified mpq4558 rev. 1.01 www.monolithicpower.com 14 5/17/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. input capacitor the input current to the step-down converter is discontinuous and therefore requires a capacitor to supply the ac current to the step-down converter while maintaining the dc input voltage. use capacitors with low equivalent series resistance (esr) for the best performance. ceramic capacitors are preferred, but tantalum or low-esr electrolytic capacitors may also suffice. for simplification, choose the input capacitor with an rms current rating greater than half of the maximum load current. the input capacitor (c1) can be electrolytic, tantalum or ceramic. when using electrolytic or tantalum capacitors, include a small, high-quality ceramic capacitor? i.e. 0.1 f?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 the input. the input voltage ripple caused by the capacitance can be estimated by: ? ? ? ? ? ? ? ? ? = in out in out s load in v v 1 v v 1 c f i v output capacitor the output capacitor (c2) maintains the dc output voltage. use ceramic, tantalum, or low- esr electrolytic capacitors for best results. low esr capacitors are preferred to keep the output voltage ripple low. the output voltage ripple can be estimated by: ? ? ? ? ? ? ? ? + ? ? ? ? ? ? ? ? ? = 2 c f 8 1 r v v 1 l f v v s esr in out s out out where l is the inductor value and r esr is the esr value of the output capacitor. for 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: ? ? ? ? ? ? ? ? ? = in out 2 s out out v v 1 2 c l f 8 v v for tantalum or electrolytic capacitors, the esr dominates the impedance at the switching frequency. for simplification, the output ripple can be approximated as: esr in out s out out r v v 1 l f v v ? ? ? ? ? ? ? ? ? = the characteristics of the output capacitor also affect the stability of the regulation system. the mpq4558 can be optimized for a wide range of capacitances and esr values. compensation components mpq4558 employs current-mode control for easy compensation and fast transient response. the comp pin controls the system stability and transient response?the comp pin is the output of the internal error amplifier. a capacitor-resistor combination in series sets a pole-zero combination to control the characteristics of the control system. the dc gain of the voltage feedback loop is given by: out fb vea cs load vdc v v a g r a = where ? a vea is the error amplifier voltage gain, 400v/v, ? g cs is the current sense transconductance,5.6a/v, and ? r load is the load resistor value. the system has two poles of importance: one is caused by the compensation capacitor (c3) and the output resistor of error amplifier; the other is caused by the output capacitor and the load resistor. these poles are located at: = ea p1 vea g f 2 c3 a = p2 load 1 f 2 c2 r where, g ea is the error amplifier transconductance, 120 a/v. the system has one zero of importance from c3 and the compensation resistor (r3). this zero is located at: = z1 1 f 2 c3 r3
mpq4558 ? 1a, 2mhz, 55v step-down converter, aec-q100 qualified mpq4558 rev. 1.01 www.monolithicpower.com 15 5/17/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. the system may have another important zero if the output capacitor has a large capacitance or a high esr value. the zero, due to the esr and the output capacitor value, is located at: = esr esr 1 f 2 c2 r in this case, a third pole set by the compensation capacitor (c5) and r3 compensates for the effect of the esr zero on the loop gain. this pole is located at: = p3 1 f 2 c5 r3 the compensation network shapes the converter transfer function for a desired loop gain. the feedback-loop unity gain at the system crossover frequency is important: lower crossover frequencies result in slower line and load transient responses, while higher crossover frequencies can destabilize the system. generally, set the crossover frequency to approximately 1/10 of the switching frequency. table 3: compensation values for typical output voltage/capacitor combinations v out (v) l (h) c2 (f) r3 (k ? ) c3 (pf) c6 (pf) 1.8 4.7 33 32.4 680 none 2.5 4.7 - 6.8 22 26.1 680 none 3.3 6.8 -10 22 68.1 220 none 5 15 - 22 33 47.5 330 none 12 10 22 16 470 2 to optimize the compensation components for conditions not listed in table 3, use the following procedure. 1. choose r3 to set the desired crossover frequency. determine the r3 value from the following equation: = cout ea cs fb 2 c2 f v r3 gg v where f c is the desired crossover frequency. 2. choose c3 to achieve the desired phase margin. for applications with typical inductor values, set the compensation zero?f z1 ?below ? the crossover frequency to provide sufficient phase margin. determine c3 from the following equation: > c 4 c3 2 r3 f 3. determine if c5 is required?if the esr zero of the output capacitor is located at less than 1/2 f s , or if the following relationship is valid: < s esr f 1 2 c2 r 2 if this is the case, then add c5 to set the pole f p3 at the location of the esr zero. determine the c5 value by the equation: = esr c2 r c5 r3 high-frequency operation the mpq4558 switching frequency can be programmed up to 2mhz by an external resistor. the minimum mpq4558 on-time is typically about 100ns. pulse-skipping operation can be seen more easily at higher switching frequencies due to the minimum on-time. since the internal bootstrap circuitry has higher impedance that may not be adequate to charge the bootstrap capacitor during each (1-d)t s charging period, add an external bootstrap charging diode if the switching frequency is about 2mhz (see external bootstrap diode section for detailed implementation information). with higher switching frequencies, the inductive reactance (xl) of the capacitor dominates so that the esl of the input/output capacitor determines the input/output ripple voltage at higher switching frequencies. because of this ripple, use high- frequency ceramic capacitors for the input decoupling capacitor and output the filtering capacitor for high-frequency operation. layout becomes more important when the device switches at higher frequencies. for best results,
mpq4558 ? 1a, 2mhz, 55v step-down converter, aec-q100 qualified mpq4558 rev. 1.01 www.monolithicpower.com 16 5/17/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. place the input decoupling capacitor and the catch diode as close to the mpq4558 (vin pin, sw pin and pgnd) as close as possible with short and wide traces. this can help to greatly reduce the voltage spikes on the sw node, and lower the emi noise level. route the feedback trace as far from the inductor and noisy power traces as possible. if possible, run the feedback trace on the opposite side of the pcb opposite from the inductor with a ground plane separating the two. placing the compensation components close to the mpq4558. avoid placing the compensation components close to or under the high-dv/dt sw node, or inside the high-di/dt power loop. if this is not possible, route a ground plane to isolate the circuit. switching loss is expected to increase at high switching frequencies. to help to improve the thermal conduction, add grid of thermal vias under the exposed pad. use small vias (15mil barrel diameter) so that the plating process fills the holes, thus aiding conduction to the other side. excessively large holes can cause solder wicking during the reflow soldering process. the typical pitch (distance between the centers) between thermal vias is typically 40mil. external bootstrap diode an external bootstrap diode may enhance the regulator efficiency. for the cases described below, add an external bst diode from 5v to the bst pin: ? there is a 5v rail available in the system; ? v in is no greater than 5v; ? v out is between 3.3v and 5v; this diode is also recommended for high-duty? cycle operation (when v out /v in > 65%) applications. the bootstrap diode can be a low-cost one such as in4148 or bat54. mpq4558 sw bst 0.1 f 5v figure 2: external bootstrap diode at no load or light load, the converter may operate in pulse-skipping mode to maintain the output voltage in regulation: there is less time to refresh the bs voltage. for sufficient gate voltage under such operating conditions, chose v in ? v out > 3v. for example, if v out = 3.3v, v in needs to be greater than 3.3v+3v=6.3v for sufficient bst voltage at no load or light load. to meet this requirement, the en pin can program the input uvlo voltage to v out +3v.
mpq4558 ? 1a, 2mhz, 55v step-down converter, aec-q100 qualified mpq4558 rev. 1.01 www.monolithicpower.com 17 5/17/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. typical application circuits c1 4.7uf 100v c3 680pf c5 ns r2 40.2k r1 49.9k l1 4.7uh c4 100nf c2 33uf 16v d1 v out 1.8v v in vin en freq gnd bst sw fb comp mpq4558 en r5 100k r4 200k r3 32.4k r6 36.5k 6 10 1,2 5 4 8,9 3 7 figure 3?1.8v output typical application schematic c1 4.7uf 100v c3 330pf c5 ns r2 40.2k r1 210k l1 15uh c4 100nf c2 33uf 16v d1 v out 5v v in vin en freq gnd bst sw fb comp mpq4558 en r5 100k r4 200k r3 47.5k r6 17.4k 6 10 1,2 5 4 8,9 3 7 figure 4?5v output typical application schematic
mpq4558 ? 1a, 2mhz, 55v step-down converter, aec-q100 qualified mpq4558 rev. 1.01 www.monolithicpower.com 18 5/17/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. pcb layout guide pcb layout is very important to achieve stable operation. duplicate the evb layout below for optimal performance. for changes, please follow these guidelines and use figure 3 for reference. 1) keep the switching-current path short and minimize the loop area formed by the input capacitor, high-side mosfet and external switching diode. 2) place the bypass ceramic capacitors close to the v in pin. 3) use short and direct feedback connections. place the feedback resistors and compensation components as close to the chip as possible. 4) route the sw path away from sensitive analog areas such as the fb path. 5) connect in, sw, and gnd, respectively, to a large copper area to cool the chip to improve thermal performance and long- term reliability. mpq4558 comp fb freq en vin gnd sw bst v out 3.3v @ 1a v in 8v to 55v control c1 c4 680pf d1 c3 100nf c2 l1 r1 127k r2 40.2k r3 200k r4 24k mpq4558 typical application circuit r6 freq 1 2 3 4 8 7 6 5 fb comp en sw bst vin gnd c4 c1 r2 r3 c3 r1 r5 r4 gnd gnd vin vo sw l1 c2 d1 gnd top layer bottom layer MPQ4558DN layout guide
mpq4558 ? 1a, 2mhz, 55v step-down converter, aec-q100 qualified mpq4558 rev. 1.01 www.monolithicpower.com 19 5/17/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. c4 c1 r2 r3 c3 r1 r5 r4 gnd gnd vin vo sw l1 c2 sw en fb d1 sw comp r6 gnd vin freq bst 6 7 8 1 2 3 4 5 10 9 vin gnd top layer bottom layer mpq4558dq layout guide figure 3: mpq4558 typical application circuit and pcb layout guide
mpq4558 ? 1a, 2mhz, 55v step-down converter, aec-q100 qualified mpq4558 rev. 1.01 www.monolithicpower.com 20 5/17/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. package information soic8 (exposed pad) see detail "a" 0.0075(0.19) 0.0098(0.25) 0.050(1.27) bsc 0.013(0.33) 0.020(0.51) seating plane 0.000(0.00) 0.006(0.15) 0.051(1.30) 0.067(1.70) top view front view side view bottom view note: 1) control dimension is in inches. dimension in bracket is in millimeters. 2) package length does not include mold flash, protrusions or gate burrs. 3) package width does not include interlead flash or protrusions. 4) lead coplanarity (bottom of leads after forming) shall be 0.004" inches max. 5) drawing conforms to jedec ms-012, variation ba. 6) drawing is not to scale. 0.089(2.26) 0.101(2.56) 0.124(3.15) 0.136(3.45) recommended land pattern 0.213(5.40) 0.063(1.60) 0.050(1.27) 0.024(0.61) 0.103(2.62) 0.138(3.51) 0.150(3.80) 0.157(4.00) pin 1 id 0.189(4.80) 0.197(5.00) 0.228(5.80) 0.244(6.20) 14 85 0.016(0.41) 0.050(1.27) 0 o -8 o detail "a" 0.010(0.25) 0.020(0.50) x 45 o 0.010(0.25) bsc gauge plane
mpq4558 ? 1a, 2mhz, 55v step-down converter, aec-q100 qualified 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. mpq4558 rev. 1.01 www.monolithicpower.com 21 5/17/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. 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

▲Up To Search▲

Price & Availability of MPQ4558DN

	To Download MPQ4558DN Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .