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mic4930 hyper speed control? 3a buck regulator hyper speed control is a trademark of micrel, inc . micrel inc. ? 2180 fortune drive ? san jose, ca 95131 ? usa ? tel +1 (408) 944 - 0800 ? fax + 1 (408) 474 - 1000 ? http://www.micrel.com march 20 , 20 14 revision 1.1 general description the mic4930 is a high - efficiency, 3a synchronous buck regulator with ultra - fast transient response perfectly suited for supplying processor core and i/o v oltages from a 5v or 3.3v bus. the mic4930 provides a switching frequency up to 3.3mhz while achieving peak efficiencies up to 95%. an additional benefit of high - frequency operation is very low output ripple voltage throughout the entire load range with th e use of a small output capacitor. the mic4930 is designed for use with a very small inductor, down to 1h, and an output ceramic capacitor as small as 10f without the need for external ripple injection. a wide range of output capacitor types and values c an also be accommodated. the mic4930 supports safe start - up into a pre - biased output. the mic4930 is available in a 10 - p in 3mm 4mm dfn package with an operating junction tempe rature range from C 40 c to +125 c. the mic4930 is pin - to - pin compatible with th e 5a - rated mic4950yfl. datasheets and support documentation are available on micrels web site at : www.micrel.com . features ? input voltage: 2.7v to 5.5v ? 3a output current ? up to 95% efficiency ? up to 3.3mhz operation ? sa fe start - up into a pre - biased output ? power good output ? ultra - fast transient response ? low output voltage ripple ? low r ds(on) integrated mosfet switches ? 0.01 a shutdown current ? thermal shutdown and current limit protection ? output voltage as low as 0.7v ? 3mm 4mm dfn - 10l ? C 40 ? c to +125 ? c junction temperature range applications ? dtvs ? set - top boxes ? printers ? dvd players ? distributed power supplies typical application
micrel, inc. mic4930 march 20 , 20 14 2 revision 1.1 ordering information part number ( 1 ) top mark temperature range package ( 2 ) lead finish MIC4930YFL mic4930 C 40 c t j +125 c 10 - pin 3mm 4mm dfn pb - free note: 1. other options are available. contact micrel for details. 2. dfn is a green, rohs - compliant package. lead finish is nipdau. mold compound is halogen free. pin configuration 3mm 4mm dfn (fl) (top view) pin description pin number pin name pin function 1 , 2, ep pgnd power ground. 3, 8 pvin power input voltage: connect a 10 f ceramic capacitor between pvin and pgnd for input decoupling. pins 3 and 8 are internally connected inside the package. 4 avin analog input voltage: connect a 1 f ceramic capacitor between avin and agnd to decouple the noise for the internal reference and error comparator. 5 agnd analog ground input: connect to a quiet ground plane for best operation. do not route power switching currents on the agnd net. connect agnd and pgnd nets together at a single point. 6 fb feedback (input): connect an external divider between vout and agn d to program the output voltage. 7 pg power good (output): open - drain output. a pull - up resistor from this pin to a voltage source is required to detect an output power - is - good condition. 9 en enable (input): logic high enables operation of the regulator. logic low will shut down the device. do not leave floating. 10 sw switch (output): internal power mosfet output switches.
micrel, inc. mic4930 march 20 , 20 14 3 revision 1.1 absolute maximum ratings ( 3 ) pvin, avin supply voltage (v in ) .................... C 0.3v to +6 v sw output switch voltage (v sw ) . ..................... C 0.3v to v in en, pg (v en , v pg ) ................................ ............. C 0.3v to v in fb feedback input voltage (v fb ) ...................... C 0.3v to v in storage temperature (t s ) ......................... C 65c to +150 c esd rating ( 5 ) ................................ ........................ 2 kv , hbm operating ratings ( 4 ) supply voltage (v in ) ................................ ..... +2.7v to +5.5 v enable input voltage (v en ) ................................ ..... 0v to v in junction temperature range (t j ) ....... C 40c t j +12 5c thermal resistance dfn - 10 ( ? ja ) ................................ ...................... 35 c/w electrical characteristics ( 6 ) v in = v en = 3.3v; l = 1.0 h ; t a = 25c, c in = 10 h , c out = 10 h unless otherwise specified. b old values indicate C 40c t j +85c, unless otherwise noted. symbol parameter condition min . typ . max . units v in supply voltage range 2.7 5.5 v v uvlo un dervoltage lockout threshold (turn - on) 2.41 2.5 2.61 v v uvloh undervoltage lockout hysteresis 400 mv i q quiescent current i out = 0ma, fb >1.2 v fb(nominal) 0.8 2 ma i sd shutdown current v en = 0v 0.01 2 a v fb feedback voltage 0.609 0.625 0.640 v i limit current limit fb = 0.9v v fb(nominal) 3.5 5.75 8 a linereg output voltage line regulation v in = 2.7v to 3.5v, v outnom = 1.8v, i load = 20ma 1 %/v v in = 4.5v to 5.5v if v outnom load = 20ma loadreg output voltage load regulation 20ma < i load < 500ma, v in = 3.6v if v outnom < 2.5v 0.3 % 20ma < i load < 500ma, v in = 5.0v if v outnom load < 3a, v in = 3.6v if v outnom < 2.5v 1 % 20ma < i load < 3ma, v in = 5.0v if v outnom dson - p pwm switch on resistance i sw = 1a p - channel mosfet 30 m ? dson - n i sw = 1a n - channel mosfet 25
micrel, inc. mic4930 march 20 , 20 14 4 revision 1.1 electrical characteristics continued ( 6 ) v in = v en = 3.3v; l = 1.0 h ; t a = 25c, c in = 10 h, c out = 10 h unless otherwise specified. b old values indicate C 40c t j +85c, unless otherwise noted. symbol parameter condition min . typ . max . units t on maximum turn - on time v in = 4.5v, v fb = 0.5v 665 ns v in = 3.0v, v fb = 0.5v 1000 v in = 2.7v, v fb = 0.5v 1120 t off minimum turn - off time v in = 3.0v, v fb = 0.5v 176 ns t soft - on soft - start time v out = 90% of v outnom 500 s v en enable threshold turn - on 0.5 0.8 1.2 v i en enable input current 0.1 1 a v outpg power good threshold rising 82 88 94 % v outpgh power good hysteresis 7 % t sd overtemperature shutdown 150 c t sdh overtemperature shutdown hysteresis 20 c notes: 3. exceeding the absolute maximum ratings may damage the device. 4. the device is not guaranteed to function outside its operating ratings. 5. devices are esd sensitive. handling precautions are recommended. human body model, 1.5k ? in series with 100pf. 6. specification for packaged product only .
micrel, inc. mic4930 march 20 , 20 14 5 revision 1.1 typical characteristics
micrel, inc. mic4930 march 20 , 20 14 6 revision 1.1 typical characteristics (continued) 2.0 2.2 2.4 2.6 2.8 3.0 -50 -20 10 40 70 100 130 switching frequency (mhz) temperature ( c) switching frequency vs. temperature v in = 3.3v v out = 1.8v i out = 0a
micrel, inc. mic4930 march 20 , 20 14 7 revision 1.1 functional characteristics
micrel, inc. mic4930 march 20 , 20 14 8 revision 1.1 functional characteristics (continued)
micrel, inc. mic4930 march 20 , 20 14 9 revision 1.1 functional block diagram
micrel, inc. mic4930 march 20 , 20 14 10 revision 1.1 functional description pvin the power input (pvin) pin provides power to the internal mosfets for the switch mode regulator section of the mic4930. the input supply operating range is from 2.7v to 5.5v. a low - esr ceramic capacitor of at least 10 f is required to bypass from pvin to (power) gnd. see the app lication information section for further details. avin the analog power input (avin) pin provides power to the internal control and analog supply circuitry. careful layout should be considered to ensure that high - frequency switching noise caused by pvin is reduced before reaching avin. always place a 1 f minimum ceramic capacitor very close to the ic between the avin and agnd pins. for additional high - frequency switching noise attenuation, rc filtering can be used (r = 10 ? ). en a logic high signal on the enable (en) pin activates the output of the switch. a logic low on en deactivates the output and reduces the supply current to a nominal 0.01 a. do not leave this pin floating. sw the switch (sw) pin connects directly to one side of the inductor and provid es the current path during switching cycles. the other end of the inductor is connected to the load and output capacitor. due to the high speed switching on this pin, the switch node should be routed away from sensitive nodes whenever possible to avoid unw anted injection of noise. pgnd the power ground (pgnd) pin is the ground return terminal for the high current in the switching node sw. the current loop for the pgnd should be as short as possible and kept separate from the agnd net whenever applicable. ag nd the analog ground (agnd) pin is the ground return terminal for the biasing and control circuitry. the current loop for the signal ground should be separate from the power ground (pgnd) loop. refer to the layout recommendations for further details. pg th e power - is - good (pg) pin is an open - drain output that indicates logic high when the output voltage is typically above 88% of its steady - state voltage. a pull - up resistor of 10k ? or greater should be connected from pg to vout. fb to program the output volta ge, an external resistive divider network is connected to this pin from the output voltage to agnd, as shown in the typical application circuit on page 1, and is compared to the internal 0.625v reference within the regulation loop. the following formula is used to program the output voltage. eq. 1 recommended feedback resistor values: v out r1 r2 1.0v 120 k 180k 1.2v 274k 294k 1.5v 316k 22 6 k 1.8v 3 01 k 1 60 k 2.5v 3 16 k 10 5 k 3.3v 309k 71.5k the feed - forward capacitor (c f in the typical application diagram) is typically in the range of 22pf to 39pf. the mic4930 features an internal ripple injection network, whose current is injected into the fb node and integrated by c f . thus, the waveform at fb i s approximately a triangular ripple. the size of c f dictates the amount of ripple amplitude at the fb node. smaller values of c f yield higher fb ripple amplitudes and better stability, but also somewhat degrade line regulation and transient response. hyper speed control ? mic4930 uses an on - and off - time proprietary ripple - based control loop that features three different timers: ? minimum on time ? maximum on time ? minimum off time when the required duty cycle is very low, the required off time is typically far f rom the minimum off time limit (about 176ns typically). in this case, the mic4930 operates by delivering a determined on time at each switching cycle, depending on the input voltage. a new on time is invoked by the error comparator when the fb voltage fall s below the regulation threshold. in this mode, the mic4930 operates as an adaptive constant - on - time ripple controller with nearly constant switching frequency. regulation takes place by controlling the valley of the fb ripple waveform. when higher duty cy cles are required, regulation can no longer be maintained by decreasing the off time below ? ? ? ? ? ? ? ? ? r2 r1 1 v v ref out
micrel, inc. mic4930 march 20 , 20 14 11 revision 1.1 the minimum off time limit. when this limit is reached, the off time is no longer reduced, and the mic4930 smoothly transitions to an on - time modulation mode. in the on - time modulation region, frequency reduces with the increase of the required on - time / duty cycle, and regulation finally takes place on the peak of the fb ripple waveform. note that because of the shift of the regulation threshold between different mod es, line regulation might suffer when the input voltage and/or duty cycle variations force the mic4930 to switch form one regulation mode to the other. in applications where wide input voltage variations are expected, ensure that the line regulation is ade quate for the intended application.
micrel, inc. mic4930 march 20 , 20 14 12 revision 1.1 application information the mic4930 is a highly efficient, 3a synchronous buck regulator ideally suited for supplying processor core and i/o voltages from a 5v or 3.3v bus. input capacitor a 10f ceramic capacitor or greater should be placed close to the pvin pin and pgnd pin for bypassing. a x5r or x7r temperature rating is recommended for the input capacitor. take into account c vs. bias effect in order to estimate the effective capacitance and the input ripple at the v in voltage. output capacitor the mic4930 is designed for use with a 10f or greater ceramic output capacitor. increasing the output capacitance will lower output ripple and improve load transient response. a low equ ivalent series resistance (esr) ceramic output capacitor is recommended based upon performance, size , and cost. ceramic capacitors with x5r or x7r temperature ratings are recommended. inductor selection when selecting an inductor, it is important to consid er the following factors: ? inductance ? rated current value ? size requirements ? dc resistance (dcr) ? core losses the mic4930 is designed for use with a 1h to 2.2h inductor. for faster transient response, a 1h inductor will yield the best result. for lower out put ripple, a 2.2h inductor is recommended. inductor current ratings are generally given in two methods : permissible dc current, and saturation current. permissible dc current can be rated for a 20c to 40c temperature rise. saturation current can be rat ed for a 10% to 30% loss in inductance. ensure that the nominal current of the application is well within the permissible dc current ratings of the inductor, also depending on the allowed temperature rise. note that the inductor permissible dc current rati ng typically does not include inductor core losses. these are a very important contribution to the total inductor core loss and temperature increase in high - frequency dc - to - dc converters, since core losses increase with at least the square of the excitatio n frequency. for more accurate core loss estimation, it is recommended to refer to manufacturers datasheets or websites. when saturation current is specified, make sure that there is enough design margin, so that the peak current does not cause the induct or to enter saturation. also pay attention to the inductor saturation characteristic in current limit. the inductor should not heavily saturate even in current limit operation, otherwise the current might instantaneously run away and reach potentially dest ructive levels. typically, ferrite - core inductors exhibit an abrupt saturation characteristic, while powedered - iron or composite inductors have a soft - saturation characteristic. peak current can be calculated by using equation 2 . eq. 2 as shown by the calculation above, the peak inductor current is inversely proportional to the switching frequency and the inductance. the lower the switching frequency or inductance, the higher the peak current. as input v oltage increases, the peak current also increases. the size of the inductor depends on the requirements of the application. refer to the typical application circuit and bill of materials for details. dc resistance (dcr) is also important. while dcr is inv ersely proportional to size, dcr can represent a significant efficiency loss. refer to the efficiency considerations subsection. efficiency considerations efficiency is defined as the amount of useful output power, divided by the amount of power supplied (see typica l characteristics section ) . eq. 3 there are two types of losses in switching converters; dc losses and switching losses. dc losses are simply the power dissipation of i 2 r. power is dissipated in the high side switch during the on cycle. power loss is equal to the high side mosfet r dson multiplied by the switch current squared. during the off cycle, the low side n - channel mosfet conducts, al so dissipating power. the d evice operating current also r educes efficiency. the product of the quiescent (operating) current and the supply voltage represents another dc loss. the current required driving the gates on and off at high frequency and the switching transitions make up the switching losses. at the higher currents for w hich the mic4930 is designed , efficiency loss is dominated by mosfet r dson and inductor losses. higher input supply voltages will increase the gate - to - source threshold on the internal mosfets, thereby reducing the internal r dson . this improves efficiency by reducing dc losses in the device. all but the inductor losses are inherent to the device. in that case, ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? l f 2 /v v 1 v i i in out out out peak 100 i v i v % efficiency in in out out ? ? ? ? ? ? ? ? ? ? ? ?
micrel, inc. mic4930 march 20 , 20 14 13 revision 1.1 inductor selection becomes increasingly critical in efficiency calculations. as the inductors are reduced in size, the dc resista nce (dcr) can become quite significant. the dcr losses can be calculated as in: p dcr = i out 2 x dcr eq. 4 from that, the loss in efficiency due to inductor dcr and core losses (p core ) can be calculated as in equation 5. eq. 5 external ripple injection the mic4930 control loop is ripple - based, and relies on an internal ripple injection network to generate enough ripple amplitude at the fb pin when negligible output voltage rip ple is present. the internal ripple injection network is typically sufficient when recommended r1 - r2 and c f values are used. the fb ripple amplitude should fall in the 20mv to 100mv range. if significantly lower divider resistors and/or higher c f values ar e used, the amount of internal ripple injection may not be sufficient for stable operation. in this case , external ripple injection is needed. this is accomplished by connecting a series r inj - c inj circuit between the sw and the fb pins, as shown in figure 1. figure 1 . external ripple injection the injected ripple is eq. 6 with k div given by eq. 7 and v in = power stage input voltage d = v out /v in = duty cycle f sw = switching frequency = (r1//r2//r inj ) c f in equations 6 and 7, it is assumed that the time constant associated with c f must be greater than the switching period. eq. 8 100 p p i v i v 1 (%) loss efficiency core dcr out out out out ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? sw div in fb(pp) f 1 d) - (1 d k v v r1//r2 r r1//r2 k inj div ? ? 1 t f 1 sw ?? ? ? ? ?
micrel, inc. mic4930 march 20 , 20 14 14 revision 1.1 evaluation board circuit bill of materials item part number manufacturer description qty. c1, c2 c2012x5r1a106m125ab tdk ( 7 ) ceramic capacitor, 10 f, 10v x5r, size 0805 2 grm219r61a106me44 murata ( 8 ) c3 c1608c0g1h220j080aa tdk ceramic capacitor, 22pf, 50v, c0g, size 0603 1 grm1885c1h220ja01 murata c4 c1608x5r1a105m080ac tdk ceramic capacitor, 1 f, 10v, x5r, size 0603 1 grm185r61a105me26 murata c5 dnp, size 0603 0 c6 dnp, size 1210 0 c7 dnp, radial, 8mm diameter polarized capacitor 0 l1 rlf7030t - 1r0n6r4 tdk 1 h, 6.4a, 7.3m ? , l7.3mm w6.8mm h3.2mm 1 clf6045t - 1r0n tdk 1h, 4.5a, 11m?, l6.2mm w5.9mm h4.5mm vlp6045lt - 1r0n tdk 1h, 6.5a, 13m?, l6.8mm w6.8mm h4.5mm cdrh5d28rh125np - 1r0pc sumida ( 9 ) 1h, 4.1a, 13.5m?, l6.3mm w6.2mm h3.0 mm r1 crcw06033013fk vishay ( 10 ) resistor, 301k ? , size0603 1 r2 crcw06031603fk vishay resistor, 160k ? , size 0603 1 r3 dnp, size 0603 0 r4 crcw060310r0fk vishay resistor, 10 ? , size 0603 1 r5 crcw06031002fk vishay resistor, 10k ? , size 0603 1 r6 crcw06031003fk vishay resistor, 100k ? , size 0603 1 r7 crcw060349r9fk vishay resistor, 49.9 ? , size 0603, for monitoring sw node only 1 u1 MIC4930YFL micrel, inc. ( 11 ) hyper speed control ? 3a buck regulator 1 notes: 7. tdk : www.tdk.com . 8. murata : www.murata.com . 9. sumida : www.sumida.com . 10. vishay : www.vishay.com . 11. micrel, inc.: www.micrel.com .
micrel, inc. mic4930 march 20 , 20 14 15 revision 1.1 pcb layout recommendations top layer bottom layer
micrel, inc. mic4930 march 20 , 20 14 16 revision 1.1 package information ( 12 ) 10 - pin dfn 3mm x 4mm (fl) note: 12. package information is correct as of the publication date. for updates and most current information, go to www.micrel.com .
micrel, inc. mic4930 march 20 , 20 14 17 revision 1.1 micrel, inc. 2180 fortune drive san jose, ca 95131 usa tel +1 (408) 944 - 0800 fax +1 (408) 474 - 1000 web http://www.micrel.com micrel makes no representations or warranties with respect to the accuracy or completeness of the information furnished in th is data sheet. this information is not intended as a warranty and micrel does not assume responsibility for its use. micrel reserves the right to change circuitry, specifications and descriptions at any time without notice. no license, whether express, implied, arising by estoppel or otherwise, to any intellectual property rights is granted by this document. except as provided in micrels terms and conditions of sale for such products, micrel assumes no liability purchasers use or sale of micrel products for use in life support appl iances, devices or systems is a purchasers own risk and purchaser agrees to fully ? 20 14 micrel, incorporated.

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