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MP2380 5a, 21v, 600khz step-down converter MP2380 rev.1.2 www.monolithicpower.com 1 5/26/2008 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2008 mps. all rights reserved. the future of analog ic technology description the MP2380 is a monolithic step-down switch mode converter with a built in high-side power mosfet. it achieves 5a continuous output current over a wide input supply range with excellent load and line regulation. current mode operation provides fast transient response and eases loop stabilization. fault condition protection includes cycle-by-cycle current limiting and thermal shutdown. the MP2380 requires a minimum number of readily available standard external components and is available in an 8-pin soic package with exposed pad. features ? wide 4.5v to 21v operating input range ? 5a continuous output current ? 45m ? internal power mosfet switch ? power good indicator ? fixed 600khz frequency ? synchronizable up to 1.5 mhz ? cycle-by-cycle over current protection ? thermal shutdown ? output adjustable from 0.8v ? stable with low esr output ceramic capacitors ? available in a thermally enhanced 8-pin soic package applications ? distributed power systems ? battery charger ? pre-regulator for linear regulators ?mps? and ?the future of analog ic technology? are registered trademarks of monolithic power systems, inc. typical application MP2380 sw fb bst 1 5 4 2 gnd in en/sync v out 3.3v @ 5a d1 b530c v in off on pg power good v cc vcc 8 7 6 3 100 95 90 85 80 75 70 65 60 55 50 efficiency (%) 12 45 3 output current (a) v in =4.5v v in =12v v out =3.3v efficiency vs output current
MP2380 ? 5a, 21v, 600khz step-down converter MP2380 rev.1.2 www.monolithicpower.com 2 5/26/2008 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2008 mps. all rights reserved. package reference sw bst vcc gnd in en/sync pg fb 1 2 3 4 8 7 6 5 top view exposed pad on backside part number* package temperature MP2380dn soic8e ?40 c to +85 c * for tape & reel, add suffix ?z (e.g. MP2380dn?z) for rohs compliant packaging, add suffix ?lf (e.g. MP2380dn?lf?z) absolute maxi mum ratings (1) supply voltage v in ....................................... 23v v sw ............................................................... 24v v bst -v sw ........................................................ 6v all other pins................................. ?0.3v to +6v junction temperature...............................150 c lead temperature ....................................260 c storage temperature ..............?65 c to +150 c recommended operating conditions (2) supply voltage v in ........................... 4.5v to 21v operating temperature .............?40 c to +85 c thermal resistance (3) ja jc soic8e .................................. 50 ...... 10... c/w notes: 1) exceeding these ratings may damage the device. 2) the device is not guaranteed to function outside of its operating conditions. 3) measured on approximately 1? square of 1 oz copper. electrical characteristics v in = 12v, t a = +25 c, unless otherwise noted. parameters symbol condition min typ max units feedback voltage v fb 4.5v v in 21v 0.788 0.808 0.828 v v fb = 0.8v 10 na feedback current i fb v fb = 2v 2 a switch on resistance (4) r ds(on) 45 75 m ? switch leakage v en = 0v, v sw = 0v 0 25 a current limit (4) 6.5 7.3 a oscillator frequency f sw v fb = 0.6v 400 600 800 khz fold-back frequency v fb = 0v 60 150 240 khz maximum duty cycle v fb = 0.6v 85 90 % minimum on time t on 100 ns under voltage lockout threshold rising 3.9 4.1 4.3 v under voltage lockout threshold hysteresis 880 mv en input low voltage 0.4 v en input high voltage 1.2 v v en = 2v 2 en input current v en = 0v 0 a sync frequency range (low) f syncl 300 khz sync frequency range (high) f synch 1.5 mhz enable turnoff delay t off 5.0 us supply current (shutdown) v en = 0v 25 a supply current (quiescent) v en = 2v, v fb = 1v 0.9 1.1 ma thermal shutdown 150 c power good control power good threshold rising 0.69 0.74 0.79 v power good threshold hysteresis 40 mv pg pin level v pg pg sink 4ma 0.4 v note: 4) guaranteed by design.
MP2380 ? 5a, 21v, 600khz step-down converter MP2380 rev.1.2 www.monolithicpower.com 3 5/26/2008 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2008 mps. all rights reserved. pin functions pin # name description 1 sw switch output. 2 bst bootstrap. this capacitor is needed to dr ive the power switch?s gate above the supply voltage. it is connected between sw and bs pins to form a floating supply across the power switch driver. 3 vcc bias supply. decouple this pin with a 1f ceramic capacitor. 4 gnd ground. this pin is the voltage reference for the regulated output voltage. for this reason care must be taken in its layout. this node should be placed outside of the d1 to c1 ground path to prevent switching current spikes from inducing voltage noise into the part. 5 fb feedback. an external resistor divider from the output to gnd, tapped to the fb pin sets the output voltage. to prevent current limit run away during a short circuit fault condition the frequency foldback comparator lowers the oscillator frequency when the fb voltage is below 250mv. 6 pg power good indicator. connect this pin to v cc or v out by a 100k ? pull-up resistor. the output of this pin is low if the output voltage is 10% less than the nominal voltage, otherwise it is an open drain. 7 en/sync on/off control input and synchronization pin. 8 in supply voltage. the MP2380 operates from a +4.5v to +21v unregulated input. c1 is needed to prevent large voltage spikes from appearing at the input.
MP2380 ? 5a, 21v, 600khz step-down converter MP2380 rev.1.2 www.monolithicpower.com 4 5/26/2008 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2008 mps. all rights reserved. typical performanc e characteristics v in = 12v, v out = 3.3v, l = 4.7h, t a = +25oc, unless otherwise noted. v pg 5v/div. v out 1v/div. v sw 10v/div. v out 10mv/div. v sw 10v/div. i l 2a/div. i l 10a/div. 400ns/div. short circuit steady 1ms/div. startup through enable no load output ripple i out = 5a v out 2v/div. v en 5v/div. v pg 5v/div. power down i out = 5a input ripple voltage load transient response i out = 3a to 6a step @ 1a/ s 1ms/div. startup through enable i out = 5a (resistive load) v out 2v/div. v pg 5v/div. v en 5v/div. 1ms/div. power up i out = 5a (resistive load) v in 10v/div. v out 1v/div. v pg 5v/div. v in 10v/div. i l 5a/div. v out 2v/div. v pg 5v/div. v in 100mv/div. v sw 5v/div. v out,ac 100mv/div. v sw 10v/div. i l 5a/div. 100 95 90 85 80 75 70 65 60 55 50 efficiency (%) 12 45 3 output current (a) v in =4.5v v in =12v efficiency vs output current
MP2380 ? 5a, 21v, 600khz step-down converter MP2380 rev.1.2 www.monolithicpower.com 5 5/26/2008 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2008 mps. all rights reserved. typical performanc e characteristics (continued) v in = 12v, v out = 3.3v, l = 4.7h, t a = +25oc, unless otherwise noted. enabled supply current vs. input voltage 1100 1050 1000 950 900 input current ( input current ( 0 5 10 15 20 25 input voltage (v) peak current vs. duty cycle peak current (a) 10 0 2 4 6 8 10 30 50 70 90 duty cycle (%) 80 70 60 50 40 30 20 10 0 case temperature ( o c) 01234 6 5 output current (a) 1.0002 1.0000 0.9998 0.9996 0.9994 0.9992 0.9990 0.9998 0.9986 normalized output voltage 01234 6 5 output current (a) 1.0025 1.0020 1.0015 1.0010 1.0000 0.9995 0.9990 0.9985 0.9980 normalized output voltage 0 5 10 15 20 25 input voltage (v) case temperature vs. output current load regulation disabled supply current vs. input voltage 0.45 0.40 0.35 0.30 0.25 0.20 0.15 0.10 0.05 0 0 5 10 15 20 25 input voltage (v) internal regulator line regulation (i byp = 10ma) 4.9 4.7 4.5 4.3 4.1 3.9 3.7 3.5 bypass voltage (v) 45 4.5 5.5 6 6.5 7 input voltage (a) v in =12v i out =0a i out =2.5a i out =5a v in =20v line regulation
MP2380 ? 5a, 21v, 600khz step-down converter MP2380 rev.1.2 www.monolithicpower.com 6 5/26/2008 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2008 mps. all rights reserved. operation in en/sync fb gnd sw bst regulator oscillator 600khz driver current sense amplifier x40 error amplifier current limit comparator pwm comparator d2 regulator reference ? -- + -- + -- + s r r q -- + vcc 54pf 1pf pg power good 0.74v 0.81 v ref figure 1?functional block diagram the MP2380 is a fixed frequency, non-synchronous step-down switching regulator with an integrated high-side power mosfet. it achieves 5a continuous output current over a wide input supply range with excellent load and line regulation. it provides a single highly efficient solution with current mode control for fast loop response and easy compensation. the MP2380 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 90% 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. power good indicator when the fb is below 0.74v, the pg pin will be internally pulled low. when the fb is above 0.74v, the pg becomes an open-drain output. error amplifier the error amplifier compares the fb pin voltage with the internal 0.81v reference (ref) and outputs a current proportional to the difference between the two. this output current is then used to charge or discharge the internal compensation network to form the 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. 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 1f ceramic capacitor for decoupling purpose is required.
MP2380 ? 5a, 21v, 600khz step-down converter MP2380 rev.1.2 www.monolithicpower.com 7 5/26/2008 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2008 mps. all rights reserved. enable/synch control the MP2380 has a dedicated enable/synch control pin (en/sync). by pulling it high or low, the ic can be enabled and disabled by en. tie en to vin for automatic start up. to disable the part, en must be pulled low for at least 5s. the MP2380 can be synchronized to external clock range from 300khz up to 1.4mhz through the en/sync pin. the internal clock rising edge is synchronized to the external clock rising edge. under-voltage lockout (uvlo) under-voltage lockout (uvlo) is implemented to protect the chip from operating at insufficient supply voltage. the MP2380 uvlo comparator monitors the output voltage of the internal regulator,vcc. the uvlo rising threshold is about 4.0v while its falling threshold is about 3.6v. internal soft-start the soft-start is implemented to prevent the converter output voltage from overshooting during startup. when the chip starts, the internal circuitry generates a soft-start voltage (ss) ramping up from 0v to 1.2v. when it is lower than the internal reference (ref), ss overrides ref so the error amplifier uses ss as the reference. when ss is higher than ref, ref regains control. over-current-protection and hiccup the MP2380 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 30% below the reference. once a uv is triggered, the MP2380 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 MP2380 exits the hiccup 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 150 c, it shuts down the whole chip. when the temperature is lower than its lower threshold, typically 140 c, 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 (figure 2). even at no load condition, as long as v in is 3v higher than v out , c4 will have enough voltage provided by v in through d2, m2, c4, l1 and c2. if (v in -v sw ) is more than 5v, u2 will regulate m2 to maintain a 5v bst voltage across c4. -- + -- + v in 5v u2 d2 m2 bst sw c4 c2 l1 v out figure 2 ? internal bootstrap charging circuit startup and shutdown if both vin 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.
MP2380 ? 5a, 21v, 600khz step-down converter MP2380 rev.1.2 www.monolithicpower.com 8 5/26/2008 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2008 mps. all rights reserved. application information the schematic on the front page shows a typical MP2380 application. the ic can provide up to 5a output current at a nominal output voltage of 3.3v. for proper thermal performance, the exposed pad of the device must be soldered down to the printed circuit board. setting the output voltage the external resistor divider is used to set the output voltage (see the schematic on front page). the feedback resistor r1 also sets the feedback loop bandwidth with the internal compensation capacitor (see figure 1). choose r1 for optimal transient response. r2 is then given by: 1 v 8 . 0 v 1 r 2 r out ? = table 1?resistor selection for common output voltages v out (v) r1 (k ? ) r2 (k ? ) 1 162 (1%) 649 (1%) 1.2 162 (1%) 324 (1%) 1.8 40.2 (1%) 32.4 (1%) 2.5 40.2 (1%) 19.1 (1%) 3.3 40.2 (1%) 13 (1%) 5 40.2 (1%) 7.68 (1%) 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. osc l in out in out f i v ) v v ( v l ? ? = where ? i l is the inductor ripple current. choose inductor current to be approximately 30% of the maximum load current, 5a. 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. 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 diode forward 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 diode v oltage/current rating manufacture b530c 30v, 5a diodes inc. mbrd630ct 30v, 6a on semi selecting the input capacitor the input capacitor (c1) reduces the surge current drawn from the input and the switching noise from the device. the input capacitor impedance at the switching frequency should be less than the input source impedance to prevent high frequency switching current from passing to the input. ceramic capacitors with x5r or x7r dielectrics are highly recommended because of their low esr and small temperature coefficients. for 5a output applications, a 22f capacitor is sufficient. selecting the output capacitor the output capacitor (c2) keeps output voltage small ripple and ensures regulation loop stability. the output capacitor impedance should be low at the switching frequency. ceramic capacitors with x5r or x7r dielectrics are recommended.
MP2380 ? 5a, 21v, 600khz step-down converter MP2380 rev.1.2 www.monolithicpower.com 9 5/26/2008 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2008 mps. all rights reserved. pcb layout guide pcb layout is very important to achieve stable operation. please follow these guidelines and take figure3 and 4 for references. 1) keep the path of switching current short and minimize the loop area formed by input cap, high-side mosfet and schottky diode. 2) keep the connection of schottky diode between sw pin and input power ground 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. 5) connect in, sw, and especially gnd respectively to a large copper area to cool the chip to improve thermal performance and long-term reliability. for single layer pcb, exposed pad should not be soldered. r3 cb c3 r2 8 7 6 5 4 3 2 1 figure 3?pcb layout for single layer top layer bottom layer figure 4?pcb layout for double layers
MP2380 ? 5a, 21v, 600khz step-down converter MP2380 rev.1.2 www.monolithicpower.com 10 5/26/2008 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2008 mps. all rights reserved. external bootstrap diode an external bootstrap diode may enhance the efficiency of the regulator, the applicable conditions of external bst diode are: z v out =5v or 3.3v; and z duty cycle is high: d= in out v v >65% in these cases, an external bst diode is recommended from the output of the voltage regulator to bst pin, as shown in fig.5 MP2380 sw bst c l bst c 5v or 3.3v out external bst diode in4148 + figure 5?add optional external bootstrap diode to enhance efficiency the recommended external bst diode is in4148, and the bst cap is 0.1~1f. by using this circuit, 5v input voltage can output 3.3v and 2.5v with just 30ma load.
MP2380 ? 5a, 21v, 600khz 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. MP2380 rev.1.2 www.monolithicpower.com 11 5/26/2008 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2008 mps. all rights reserved. package information soic8e (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

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