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MP9186 20v, 6a synchronous stepdown converter MP9186 rev. 1.0 www.monolithicpower.com 1 2/4/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibi ted. ? 2013 mps. all rights reserved. the future of analog ic technology description the MP9186 is a synchronous, rectified, step down, switchmode converter with internal power mosfets. it offers a very compact solution to achieve a 6a continuous output current over a wide input supply range with excellent load and line regulation. the MP9186 has synchronous mode operation for higher efficiency over the output current load range. currentmode operation provides a fast transient response and eases loop stabilization. full protection features include overcurrent protection and thermal shutdown. the MP9186 requires a minimal number of readilyavailable standard external components and is available in a space saving 3mm3mm 14pin qfn package. features ? wide 4.5vto20v operating input range ? 6a output current ? low r ds(on) internal power mosfets ? programmable switching frequency ? programmable en delay ? frequency sync from 300khz to 2mhz external clock ? low power mode selectable by an external signal ? external soft start ? ocp and thermal shutdown ? available in a 14pin 3x3mm qfn package applications ? dsl modems ? cable modems ? settop boxes all mps parts are lead free and adhere to the rohs directive. for mps green status, please visit mps website under products, qu ality assurance page. mps and the future of analog ic technology are registered trademarks of monolithic power systems, inc. typical application MP9186 vcc u1 r12.61k r210k r t 75kc ss 22nf 1v/6a vou t vin vcc en on off lpm c del ay 47nf r freq 30.1k enlpm freq/sync gnd ss fb sw bs t in freq/sync
MP9186 C 20v, 6a synchronous stepdown converter MP9186 rev. 1.0 www.monolithicpower.com 2 2/4/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibi ted. ? 2013 mps. all rights reserved. ordering information part number package top marking MP9186gq* qfn14 (33mm) aek * for tape & reel, add suffix Cz (eg. MP9186gqCz); package reference 1 gnd vcc bs t sw ss freq/sync agnd in en lpm gnd fb gnd sw 11 10 9 8 7 6 5 4 3 2 14 13 12 pin 1 id in absolute maximum ratings (1) v in ................................................ 0.3v to 22v v sw .................................................. .................. 0.3v (5v for <10ns) to 23v (25v for <10ns) v bst .................................................. ...v sw + 6v all other pins ................................ 0. 3v to 6v (2) lead temperature .................................. . 260c continuous power dissipation (t a = +25c) (3) 3x3 qfn14 ......................................... ....... 2.1w junction temperature .............................. 150c recommended operating conditions (4) supply voltage v in .......................... 4.5v to 20v output voltage v out ................. 0.8v to v in x90% operating junction temp. (t j ) 40c to +125c thermal resistance (5) ja jc qfn14 (3x3mm) .................... 60 ...... 12 ... c/w notes: 1) exceeding these ratings may damage the device. 2) please refer to page 9, enable control section, for absolute maximum rating of en pin. 3) the maximum allowable power dissipation is a functi on of the maximum junction temperature t j (max), the junctionto ambient thermal resistance ja , and the ambient temperature t a . the maximum allowable continuous power dissipatio n at any ambient temperature is calculated by p d (max) = (t j (max)t a )/ ja . exceeding the maximum allowable p ower dissipation will cause excessive die temperature, a nd the regulator will go into thermal shutdown. internal t hermal shutdown circuitry protects the device from permane nt damage. 4) the device is not guaranteed to function outside of its operating conditions. 5) measured on jesd517, 4layer pcb.
MP9186 C 20v, 6a synchronous stepdown converter MP9186 rev. 1.0 www.monolithicpower.com 3 2/4/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibi ted. ? 2013 mps. all rights reserved. electrical characteristics v in = 12v, t a = 25c, unless otherwise noted. parameters symbol condition min typ max units supply current (shutdown) i in v en = 0v 10 15 a supply current (quiescent) i q v en = 2v, v fb = 1v 0.8 1.2 ma hs switchon resistance hs rds on 60 m ls switchon resistance ls rds on 30 m switch leakage sw lkg v en = 0v, v sw = 0v or 12v 0 1 a current limit (6) i limit duty=40% 7.4 9.4 a oscillator frequency f sw r set =30k 400 500 600 khz maximum duty cycle d max v fb = 700mv, r set =30k 90 95 % minimum on time (6) t on_min 40 ns sync frequency range f sync 0.3 2 mhz feedback voltage v fb 782 798 814 mv feedback current i fb v fb = 800mv 25 50 na en input low voltage vil en 0.98 1.12 1.32 v en input high voltage vih en 1.32 1.50 1.78 v en pin pullup current i en 1.2 2.3 3.5 a v in undervoltage lockout threshold rising inuv vth 3.75 4 4.25 v v in undervoltage lockout threshold hysteresis inuv hys 820 mv vcc regulator v cc 5 v vcc load regulation i cc =5ma 1 % thermal shutdown (6) t sd 150 c thermal shutdown hysteresis ( 6) t sd hys 30 c soft start current i ss 5 8 11 a note: 6) guaranteed by design
MP9186 C 20v, 6a synchronous stepdown converter MP9186 rev. 1.0 www.monolithicpower.com 4 2/4/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibi ted. ? 2013 mps. all rights reserved. pin functions qfn 3 3mm pin # name description 1, 13, 14 gnd ground. connect these pins with larger copper areas to the negative terminals of the input and output capacitors. 2, 11 sw switch output. use wide pcb traces to make the connection. 3, 15 (in) in supply voltage. the MP9186 operates from a 4.5vto 20v input rail. requires c1 to decouple the input rail. use wide pcb traces and mu ltiple vias to make the connection. 4 en enable. en=1 to enable the MP9186. the en pin sourc es 2.3a current . place a capacitor from en to gnd for delayed startup. 5 lpm lowpower mode input. an activehigh signal enables lowpower mode operation. connect lpm pin to gnd to disable it and make the c onverter always operate in ccm. 6 fb feedback. connect to the tap of an external resisto r divider from the output to gnd to set the output voltage. 7 ss soft start. connect an external capacitor to progra m the softstart time for the switch mode regulator. 8 freq/ sync switching frequency program input. connect a resist or from this pin to gnd to set the switching frequency. this pin also serves as a freq uencysynchronous clock input. 9 vcc bias supply. decouple with 1f capacitor. decouple capacitor must be close enough to vcc pin to increase noise immunity. 10 bst bootstrap. requires a capacitor connected between s w and bst pins to form a floating supply across the highside switch driver. 12 agnd analog ground for internal control circuit.
MP9186 C 20v, 6a synchronous stepdown converter MP9186 rev. 1.0 www.monolithicpower.com 5 2/4/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibi ted. ? 2013 mps. all rights reserved. typical characteristics v in = 12v, v out = 1v, l = 1.5h, f s =500khz, t a = +25c, unless otherwise noted. -0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 5 8 11 14 17 20 -0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 -50-30-10 10 30 50 70 90 110130 4 6 8 10 12 14 16 18 20 22 863 864 865 866 867 868 4 6 8 10 12 14 16 18 20 22 790 792 794 796 798 800 802 804 806 808 810 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0 10.5 11.0 10 20 30 40 50 60 70 80 9.2 9.4 9.6 9.8 10.0 10.2 10.4
MP9186 C 20v, 6a synchronous stepdown converter MP9186 rev. 1.0 www.monolithicpower.com 6 2/4/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibi ted. ? 2013 mps. all rights reserved. typical performance characteristics (continued) v in = 12v, v out = 1v, l = 1.5h, f s =500khz, t a = +25c, unless otherwise noted. 0 10 20 30 40 50 60 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 60 65 70 75 80 85 90 95 100 0 1 2 3 4 5 6 v ou t 500mv/div. v in 10v/div. v sw 10v/div. i induc tor 5a/div. v ou t 500mv/div. v in 10v/div. v sw 10v/div. i induc tor 5a/div. v ou t 500mv/div. v en 5v/div. v sw 5v/div. i induc tor 1a/div. v ou t 500mv/div. v en 5v/div. v sw 10v/div. i induc tor 5a/div. v ou t 500mv/div. v en 5v/div. v sw 5v/div. i induc tor 5a/div. v ou t 500mv/div. v en 5v/div. v sw 5v/div. i induc tor 5a/div.
MP9186 C 20v, 6a synchronous stepdown converter MP9186 rev. 1.0 www.monolithicpower.com 7 2/4/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibi ted. ? 2013 mps. all rights reserved. typical performance characteristics (continued) v in =12v, v out =1v, l = 1.5h, f s =500khz, t a = +25c, unless otherwise noted. v ou t 500mv/div. v in 5v/div. v sw 5v/div. i induc tor 5a/div. v out /ac 50mv/div. v in /ac 50mv/div. v sw 10v/div. i induc tor 5a/div. v out /ac 100mv/div. i induc tor 2a/div. v ou t 500mv/div. v in 10v/div. v sw 5v/div. i induc tor 1a/div. v ou t 500mv/div. v in 10v/div. v sw 5v/div. i induc tor 5a/div. v ou t 500mv/div. v in 10v/div. v sw 5v/div. i induc tor 1a/div.
MP9186 C 20v, 6a synchronous stepdown converter MP9186 rev. 1.0 www.monolithicpower.com 8 2/4/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibi ted. ? 2013 mps. all rights reserved. functional block diagram figure 1: functional block diagram
MP9186 C 20v, 6a synchronous stepdown converter MP9186 rev. 1.0 www.monolithicpower.com 9 2/4/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibi ted. ? 2013 mps. all rights reserved. operation the MP9186 is a highfrequency, synchronous, rectified, stepdown, switchmode converter with internal power mosfets. it offers a very compact solution to achieve 6a of continuous output current over a wide input supply range with excellent load and line regulation. the MP9186 operates in a fixedfrequency, peakcurrentCmode control to regulate the output voltage. the internal clock initiates the pwm cycle, turning on the integrated highside power mosfet. the highside mosfet 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, within 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. error amplifier the error amplifier compares the fb pin voltage against the internal 0.8v reference (ref) and outputs a current proportional to the difference between the two. this output current charges or discharges the internal compensation network to form the comp voltage, which controls the power mosfet current. the optimized internal compensation network minimizes the external component count and simplifies the control loop design. internal regulator the 5v internal regulator powers most of the internal circuitries. this regulator takes the vin input and operates in the full vin range. when vin exceeds 5.0v, the output of the regulator is in full regulation. when vin is less than 5.0v, the output decreases. the part requires a 1f ceramic decoupling capacitor. enable control the MP9186 has a dedicated enable control pin (en): pulling it high or floating it enables the ic , pulling it low disables it. en must be pulled low to disable the part. the en pin is clamped internally using a 6.7v serieszenerdiode as shown in figure 2. connect the en input pin through a pullup resistor to any voltage connected to the vin pin such that the pullup resistor limits the en input current to less than 100a. for example, connecting 12v to vin, r pullup (12v C 6.7v)/100a = 53k . connecting the en pin is directly to a voltage source without any pullup resistor requires limiting the amplitude of the voltage source to below 6v to prevent damage to the zener diode. en en logic zener 6.7v typ. gnd figure 2: zener diode between en and gnd the en pin also features an internal 2.3a current source. connect a capacitor to the en pin for delayed startup. when vin exceeds the input uvlo, an internal 2.3a current source charges the external capacitor. the external capacitor connects to the noninverting input of a comparator. the part is enabled once the capacitor voltage exceeds the 1.5v internal reference voltage. frequency synchronizing the MP9186 can be synchronized to an external clock with a range from 300khz to 2mhz through the sync pin. the internal clock rising edge is synchronized to the external clock rising edge. low power mode the MP9186 can operate in discontinuous mode (dcm) and pulse skip mode (psm) under light load to improve efficiency, featured as the low power mode. to enable low power mode, connect lpm pin to vcc pin or to a voltage divider from vcc. to disable low power mode, connect lpm pin to ground and the converter will always operate in ccm. when the lpm pin connects to vcc, the inductor peak current in set internally which is about 1.58a for vin=12v, vout=1v and l=1.5h. peak inductor current also can be set
MP9186 C 20v, 6a synchronous stepdown converter MP9186 rev. 1.0 www.monolithicpower.com 10 2/4/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibi ted. ? 2013 mps. all rights reserved. by connecting lpm pin to a voltage divider from vcc with 2 external resistors. by program lpm voltage, efficiency and output ripple can be traded off and optimized. higher lpm gives higher peak inductor current thus more efficient but more output ripple. the curve of inductor peak current vs. low power mode voltage for v in =12v, v out =1v, l=1.5h is shown in figure 3. 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 figure 3: inductor peak current vs. low power mode voltage undervoltage lockout (uvlo) undervoltage lockout (uvlo) protects the chip from operating at insufficient supply voltage. the MP9186s uvlo comparator monitors the output voltage of the internal regulator, vcc. the uvlo rising threshold is 4v while its falling threshold is 3.18v. external softstart connect a capacitor from the softstart pin to ground to adjust the softstart time. when soft start begins, an internal 8a current source charges the external capacitor. the softstart capacitor connects to the noninverting input of the error amplifier. the softstart period lasts until the voltage on the softstart capacitor exceeds the 0.798v reference. at this point the reference voltage takes over at the non inverting erroramplifier input. the softstart time can be calculated as follows: ss ss 0.798v c (nf) t (ms) 8 a = if the output of the MP9186 is prebiased to a certain voltage during startup, the ic will disable the switching of both highside and lowside switches until the voltage on the internal soft start capacitor exceeds the sensed output voltage at the fb pin. overcurrentprotection the MP9186 has a hiccup mode overcurrent limit for when the inductor current peak value exceeds the set current limit threshold. when the output voltage drops below 70% of the reference, and inductor current exceeds the current limit, the MP9186 will enter hiccup mode and retry until the fault is removed. this is especially useful to ensure system safety under fault conditions. the hiccup function is disabled during softstart duration. thermal shutdown thermal shutdown prevents the chip from operating at exceedingly high temperatures. when the silicon die temperature exceeds 150c, it shuts down the whole chip. when the temperature falls below its lower threshold, typically 120c, 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. the uvlos rising threshold is 2.2v with a hysteresis of 150mv. the bootstrap capacitor voltage is regulated internally by vin through d1, m1, r5, c4, l1 and c2 (figure 4). if (v in v sw ) exceeds 5v, u1 regulates m1 to maintain a 5v bst voltage across c4. a 10 resistor placed between sw and bst capacitor is strongly recommended to reduce sw spike voltage and noise. figure 4: internal bootstrap charging circuit
MP9186 C 20v, 6a synchronous stepdown converter MP9186 rev. 1.0 www.monolithicpower.com 11 2/4/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibi ted. ? 2013 mps. all rights reserved. startup and shutdown if both vin and en exceed their respective thresholds, the chip is enabled. the reference block starts first, generating a 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 low, vin low and thermal shutdown. in shutdown, 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.
MP9186 C 20v, 6a synchronous stepdown converter MP9186 rev. 1.0 www.monolithicpower.com 12 2/4/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibi ted. ? 2013 mps. all rights reserved. application information component selection setting the output voltage the external resistor divider sets the output voltage (see typical application on page 1). the feedback resistor, r1, also sets the feedback loop bandwidth with the internal compensation capacitor. choose r1 around 10k, then r2 is: out r1 r2 v 1 0.798v = ? the ttype network (shown in figure 5) is highly recommended when v out is low. 8 fb rt r1 c ff r2 vou t figure 5: ttype network table 1 lists the recommended ttype resistors value for common output voltages. table 1: resistor selection for common output voltages v out (v) r1 (k ) r2 (k ) r t (k ) c ff ( pf ) 1 2.61(1%) 10(1%) 75(1%) 10 1.2 5.1(1%) 10(1%) 75(1%) 10 1.8 10(1%) 7.87(1%) 43(1%) 10 2.5 10(1%) 4.64(1%) 24(1%) 15 3.3 10(1%) 3.16(1%) 10(1%) 22 5 10(1%) 1.87(1%) 10(1%) 22 selecting the inductor use a 1hto10h inductor with a dc current rating of at least 25% percent higher than the maximum load current for most applications. select an inductor with a dc resistance less than 15m for best efficiency. use the following equation to derive the inductor value for most designs. out in out 1 in l osc v (v v ) l v i f ? = 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 is: 2 i i i l load ) max (l + = under lightload conditions (below 100ma), use a larger inductor for improved efficiency. setting the switching frequency an external resistor, r freq , from the freq pin to gnd sets the MP9186s oscillating frequency. the value of r freq can be calculated from: ) khz ( f ) k( r s freq 15000 = selecting the input capacitor the input current to the stepdown 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 lowesr 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 v in = 2v out , where: 2 i i load 1 c =
MP9186 C 20v, 6a synchronous stepdown converter MP9186 rev. 1.0 www.monolithicpower.com 13 2/4/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibi ted. ? 2013 mps. all rights reserved. for simplification, choose the input capacitor whose rms current rating is greater than half of the maximum load current. the input capacitor can be electrolytic, tantalum or ceramic. when using electrolytic or tantalum capacitors, place a small, highquality ceramic capacitor (e.g. 0.1f) 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: load out out in in s in i v v v 1 f c1 v v ? ? = ? ? ? ? ? selecting the output capacitor the device requires an output capacitor (c2) to maintain the dc output voltage. use ceramic, tantalum, or low esr electrolytic capacitors. use lowesr capacitors to limit the output voltage ripple. estimate the output voltage ripple with: out out out esr s 1 in s v v 1 v 1 r f l v 8 f c2 ? ? ? ? = ? + ? ? ? ? ? ? ? ? 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 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 s 1 v v v 1 v 8 f l c2 ? ? = ? ? ? ? ? for 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 s 1 v v v 1 r f l v ? ? = ? ? ? ? ? the characteristics of the output capacitor also affect the stability of the regulatory system. the MP9186 can be optimized for a wide range of capacitance and esr values. external bootstrap diode an external bootstrap diode can enhance the efficiency of the regulator, given the following conditions: v out is 5v or 3.3v; and duty cycle is high: d= in out v v >65% use an external bst diode from the vcc pin to the bst pinas shown in figure 6for such cases. MP9186 bst sw vcc c out l external bst diode in4148 figure 6: optional bootstrap diode the recommended external bst diode is in4148, and the bst capacitor is 0.1f to 1f.
MP9186 C 20v, 6a synchronous stepdown converter MP9186 rev. 1.0 www.monolithicpower.com 14 2/4/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibi ted. ? 2013 mps. all rights reserved. pc board layout this pcb board layout is referring to the schematic in figure 8. place the highcurrent paths (gnd, in and sw) very close to the device with short, direct and wide traces. the input decoupling capacitor needs to be placed as close as possible to the in and gnd pins. the vcc decoupling capacitor needs to be placed as close as possible to the vcc pin and multiple vias should be used on both the ground side of the vcc decoupling capacitor and the gnd pins to connect to the inner and bottom ground plane. place the external feedback resistors next to the fb pin. keep the switching node sw short and away from the feedback network. top layer bottom layer figure 7: pcb layout design example below is a design example following the application guidelines for the specifications: table 2: design example v in 12v v out 1v io 6a the detailed application schematic is shown in figure 8 . 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.
MP9186 C 20v, 6a synchronous stepdown converter MP9186 rev. 1.0 www.monolithicpower.com 15 2/4/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibi ted. ? 2013 mps. all rights reserved. typical application circuits vin 9 4 5 1 ,12 13 ,14 8 10 3 2 11 6 7 6-20v gnd vccen in bs t sw 1v/6a vou t gnd sw sw fb gnd ss lpmfreq/sync vcc en lpm freq/sync ss r990.9k c547nf c810pf MP9186 r510 c610pf r875k r12.61k r210k c722nf r751 r60 u1 figure 8: 500khz, 1v output at 6a stepdown convert er
MP9186 C 20v, 6a synchronous stepdown converter notice: the information in this document is subject to cha nge without notice. users should warrant and guaran tee that third party intellectual property rights are not infringe d upon when integrating mps products into any appli cation. mps will not assume any legal responsibility for any said applic ations. MP9186 rev. 1.0 www.monolithicpower.com 16 2/4/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibi ted. ? 2013 mps. all rights reserved. package information qfn14 (3mmx3mm) side view side view side view side view bottom view bottom view bottom view bottom view note note note note: :: : 1) all dimensions are in millimeters. 2) exposed paddle size does not include mold flash. 3) lead coplanarity shall be 0.10 millimeters max. 4) jedec reference is mo220. 5) drawing is not to scale. pin pin pin pin 1 1 1 1 id id id id marking marking marking marking top view top view top view top view pin pin pin pin 1 1 1 1 id id id id index area index area index area index area recommended land pattern recommended land pattern recommended land pattern recommended land pattern 0 00 0. .. .175 175 175 175x xx x 45 4545 45 pin pin pin pin 1 1 1 1 id idid id 0 00 0. .. . 175 175 175 175x xx x45 4545 45 typ.

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