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MIC28304 70v 3a power module hyper speed control? family general description micrel?s MIC28304 is synchronous step - down regulator module, featuring a unique adaptive on - time control architecture. the module incorporates a dc - to - dc controller, power mosfets, bootstrap diode, bootstrap capacitor and an inductor in a single package. t he MIC28304 operates over an input supply range from 4.5v to 70v and can be used to supply up to 3a of output current. the output voltage is adjustable down to 0.8v with a guaranteed accuracy of 1%. the device operates with programmable switching frequenc y from 200khz to 600khz. micrel?s hyper light load ? architecture provides the same high - efficiency and ultra - fast transient response as the hyper speed control ? architecture under the medium to heavy loads, but also maintains high efficiency under light lo ad conditions by transitioning to variable frequency, discontinuous - mode operation. the MIC28304 offers a full suite of protection features . these include under voltage lockout, internal soft - start , fold back current limit, ?hiccup? mode short - circuit prot ection , and thermal shutdown. datasheets and support documentation are available on micrel?s web site at : www.micrel.com . features ? easy to use ? stable with low - esr ceramic output capacitor ? no compensation and no induct or to choose ? 4.5v to 70v input voltage ? single - supply operation ? power g ood (pg) output ? low radiat ed emission (emi) per en55022, c lass b ? adjustable current limit ? adjustable output voltage from 0. 9 v to 24v (also limited by duty cycle) ? 2 00khz to 600khz , prog rammable switching frequency ? supports safe start - up into a pre - biased output ? ? 40 c to +125 c junction temperature range ? available in 64 - pin, 12mm 12mm 3 mm qfn package applications ? distributed power systems ? industrial, medical, telecom, and automotive typical application hyper speed control, hyperlight load, and any capacitor are trademark s 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 25, 2014 revision 1.1
micrel, inc. MIC28304 ordering information part number switching frequency features package junction temperature range lead finish MIC28304 -1 ym p 2 00khz to 600khz hyperlight load 64- pin 12mm 12mm qfn ? 40c to +125c pb - free MIC28304 - 2ym p 2 00khz to 600khz hyper speed control 64- pin 12mm 12mm qfn ? 40c to +125c pb - free pin configuration 64- pin 12mm 12mm qfn ( mp ) (top view) pin description pin number pin name pin function 1, 2, 3, 54, 64 gnd analog g round. ground for internal controller and feedback resistor network. the analog ground return path should be separate from the power ground (pgnd) return path. 4 ilim current limit s etting. connect a resistor from sw (pin #4) to ilim to set the over - current threshold for the converter. 5, 60 vin supply voltage for c ontroller. the vin operating voltage range is from 4.5v to 70 v. a 0.47 f ceramic capacitor from vin (pin # 60) to agnd is required for decoupling. the pin # 5 should be externally connected to either pvin or pin # 60 on pcb. 6, 40 to 48, 51 sw switch node and current - sense input. high current output driver return. the sw pin connects directly to the switch node. due to the high - speed switching on this pin, the sw pin should be routed away from sensitive nodes. the sw pin also senses the current by monitoring the voltage across the low - side mosfet during off time. march 25, 2014 2 revision 1.1
micrel, inc. MIC28304 pin description (continued) pin number pin name pin function 7, 8 freq switching frequency adjust input. leaving this pin open will set the switching frequency to 600khz. alternatively a resistor from this pin to ground can be used to lower the switching frequency. 9 to 13 pgnd power ground. pgnd is the return path for the buck converter power stage. the p gnd pin connects to the sources of low - side n - channel external mosfet, the negative terminals of input capacitors, and the negative terminals of output capacitors. the return path for the power ground should be as small as possible and separate from the an alog ground (gnd) return path. 14 to 22 pvin power input voltage. connection to the drain of the internal high - side power mosfet. 23 to 38 vout output voltage. connection with the internal inductor, the output capacitor should be connected from this pin to pgnd as close to the module as possible. 39 nc no connection. leave it floating. 49, 50 anode anode bootstrap diode input . anode connecti on of internal bootstrap diode, this pin should be connected to the pvdd pin. 52, 53 bstc bootstrap capacitor . connection to the internal bootstrap capacitor. leave floating, no connect. 55, 56 bstr bootstrap resistor . connection to the internal bootstrap resistor and high - side power mosfet drive circuitry. leave floating, no connect. 57 fb feedback inpu t . input to the transconductance amplifier of the control loop. the fb pin is regulated to 0.8v. a resistor divider connecting the feedback to the output is used to set the desired output voltage. 58 pgood power good output . open drain o utput, an external pull - up resistor to external power rails is required. 59 en enable input . a logic signal to enable or disable the buck converter operation. the en pin is cmos compatible. logic high enables the device, logic low shutdowns the regulator. in the disable mode, the input supply current for the device is minimized to 4 a typically. d o not pull en to pvdd. 61, 62 pvdd internal +5v linear regulator output . p vdd is the int ernal supply bus for the device . in the applications with vin < +5.5v, p vdd should be tied to vin to by - pass the linear regulator. 63 nc no connection . leave it floa ting. march 25, 2014 3 revision 1.1
micrel, inc. MIC28304 absolute maximum ratings ( 1 ) pvin, vin to pgnd ...................................... ? 0.3v to +76v pvdd , v anode to pgnd .................................. ? 0.3v to +6v v sw , v freq , v ilim , v en ........................ ? 0.3v to (pvin +0.3v) v bstc/bstr to v sw ................................................ ? 0.3v to 6v v bstc/bstr to pgnd .......................................... ? 0.3v to 82v v fb , v pg to pgnd ......................... ? 0.3v to (pvdd + 0.3v) pgnd to agnd ............................................ ? 0.3v to +0.3v junction temperature .............................................. +150c storage temperature (t s ) ......................... ? 65 c to +150 c l ead temperature (soldering, 10s) ............................ 260c esd rating ( 3) ................................................. esd sensitive operating ratings ( 2 ) supply voltage ( pvin, v in ) .............................. 4.5v to 70 v enable input (v en ) ................................................. 0v to v in v sw , v feq , v ilim , v en .............................................. 0v to v in power good (v pgood )..??????..??? ... 0v to pv dd junction temperature (t j ) ........................ ? 40 c to +125 c junction th ermal resistance 12mm 12mm qfn - 64 ( ja ) ............................ 20c/w 12mm 12mm qfn - 64 ( jc ) ............................... 5c/w electrical characteristics ( 4 ) pvin = vin = 12v, v out = 5v, v bst ? v sw = 5v; t a = 25c, unless noted. bold values indicate ? j ??& parameter condition min . typ . max . units power supply input input voltage range (pvin, vin) 4.5 70 v controller supply current ( 5 ) current into pin 60; vfb = 1.5v (MIC28304 -1) 0.4 0.75 ma current into pin 60;vfb = 1.5v (MIC28304 -2) 2.1 3 current into pin 60;ven = 0v 0.1 10 a operating current i out = 0a (MIC28304 -1) 0.7 ma i out = 0a (MIC28304 -2) 27 shutdown supply current pvin = v in = 12v, v en = 0v 4 a pvdd supply ( 5 ) pvdd output voltage vin = 7v to 70v, i pvdd = 10ma 4.8 5.2 5.4 v pvdd uvlo threshold pvdd rising 3.8 4.2 4. 7 v pvdd uvlo hysteresis 400 mv load regulation i pvdd = 0 to 40ma 0.6 2 3.6 % reference ( 5 ) feedback reference voltage t j = 25c (1.0%) 0.792 0.8 0.808 v ? j ??&? 0.784 0.8 0.816 fb bias current v fb = 0.8v 5 500 na notes: 1. exceeding the absolute maximum ratings may damage the device. 2. the device is not guaranteed to function outside its operating ratings. 3. devices are esd sensitive. handling precautions are recommended. human body model, 1.5k in series with 100pf. 4. specification for packaged product only. 5. i c tested prior to assembly. march 25, 2014 4 revision 1.1
micrel, inc. MIC28304 electrical characteristics ( 4 ) (continued) pvin = vin = 12v, v out = 5v, v bst ? v sw = 5v; t a = 25c, unless noted. bold values indicate ? j ??& parameter condition min . typ . max . units enable control en logic level high 1.8 v en logic level low 0.6 v en hysteresis 200 mv en bias current v en = 12v 5 2 0 a oscillator switching frequency freq pin = open 400 600 750 khz rfreq = 100k (freq pin -to - gnd ) 300 maximum duty cycle 85 % minimum duty cycle v fb > 0.8v 0 % minimum off - time 140 200 260 ns soft - start (5) soft - start time 5 ms short - circuit protection ( 5 ) current - limit threshold (v cl ) v fb = 0.79v ? 30 ? 14 0 mv short - circuit threshold v fb = 0v ? 23 ? 7 9 mv current - limit source current v fb = 0.79v 60 80 100 a short - circuit source current v fb = 0v 27 36 47 a leakage sw, bstr leakage current 50 a power good ( 5 ) power good threshold voltage sweep v fb from low -to - high 85 90 95 %v out power good hysteresis sweep v fb from high - to - low 6 %v out power good delay time sweep v fb from low -to - high 100 s power good low voltage v fb < 90% x v nom , i pg = 1ma 70 200 mv thermal protection overt emperature shutdown t j rising 160 c overt emperature shutdown hysteresis 4 c march 25, 2014 5 revision 1.1
micrel, inc. MIC28304 electrical characteristics ( 4 ) (continued) pvin = vin = 12v, v out = 5v, v bst ? v sw = 5v; t a = 25c, unless noted. bold values indicate ? j ??& parameter condition min . typ . max . units output characteristic output voltage ripple i out = 3a 16 mv line regulation pvin = v in = 7v to 70v, i out = 3a 0.36 % load regulation i out = 0a to 3a pvin= v in =12v (MIC28304 -1) 0.75 % i out = 0a to 3a pvin= v in =12v (MIC28304 -2) 0.05 output voltage deviation from load step i out from 0a to 3a at 5a/ s (MIC28304 - 1) 400 mv i out from 3a to 0a at 5a/ s (MIC28304 - 1) 500 i out from 0a to 3a at 5a/ s (MIC28304 - 2) 400 i out from 3a to 0a at 5a/ s (MIC28304 - 2) 500 march 25, 2014 6 revision 1.1
micrel, inc. MIC28304 typical characteristics ? table 1 . recommended component values for 275khz switching frequency v out vin r3 (r inj ) r19 r15 r1 (top feedback resistor ) r11 (bottom feedback resistor ) c10 (c inj ) c12 (c ff ) c out 5v 7v to 18 v 16.5k 75k 3.57k n 1.9 n 0.1 f 2.2nf 2x 47f /6.3v 5v 18 v to 70v 39.2 k 75k 3.57k n 1.9 n 0.1 f 2.2nf 2x 47f /6.3v 3.3v 5v to 18 v 16.5k 75k 3.57k n 3.24 n 0.1 f 2.2nf 2x 47f /6.3v 3.3v 18 v to 70v 39.2 k 75k 3.57k n 3.24 n 0.1 f 2.2nf 2x 47f /6.3v 50 55 60 65 70 75 80 85 90 95 100 0 0.5 1 1.5 2 2.5 3 efficiency (%) output current (a) efficiency vs. output current (MIC28304 - 1) v out = 5v f sw = 275khz 48vin 24vin 12vin 36vin 30 40 50 60 70 80 90 100 0 0.5 1 1.5 2 2.5 3 efficiency (%) output current (a) efficiency vs. output current (MIC28304 - 2) v out = 5v f sw = 275khz 48vin 24vin 12vin 36vin 0 1 2 3 25 40 55 70 85 100 115 load current (a) maximum ambient temperature ( c) thermal derating v out = 5v f sw = 275khz t j_max =125 c MIC28304 - 2 vin = 12v vin = 24v vin = 48v march 25, 2014 7 revision 1.1
micrel, inc. MIC28304 typical characteristics 0.00 0.40 0.80 1.20 1.60 2.00 5 10 15 20 25 30 35 40 45 50 55 60 65 70 supply current (ma) input voltage (v) vin operating supply current vs. input voltage (MIC28304 - 1) v out = 5v i out = 0a f sw = 600khz -1.0% 0.0% 1.0% 2.0% 3.0% 4.0% 5.0% 7 12 17 22 27 32 37 42 47 52 57 62 67 total regulation (%) input voltage (v) output regulation vs. input voltage (MIC28304 - 1) v out = 5.0v i out = 0a to 3a f sw = 600khz 0 0 00 00 0 0 0 0 0 0 0 60 6 0 feedback voltage (v) input voltage (v) feedback voltage vs. input voltage (MIC28304 - 1) v out = 5.0v i out = 0a f sw = 600khz 0 6 00 0 0 06 0 0 0 0 0 0 60 6 0 output voltage (v) input voltage (v) output voltage vs. input voltage (MIC28304 - 1) v out = 5v i out = 0a f sw = 600khz 000 00 00 0 60 00 0 0 0 00 supply current (ma) temperature ( c) vin operating supply current vs. temperature (MIC28304 - 1) vin = 12v v out = 5.0v i out = 0a f sw = 600khz 0.792 0.796 0.800 0.804 0.808 -50 -25 0 25 50 75 100 125 feeback voltage (v) temperature ( c) feedback voltage vs. temperature (MIC28304 - 1) vin= 12v v out = 5.0v i out = 0a f sw = 600khz 00 0 0 06 0 0 0 0 0 00 load regulation (%) temperature ( c) load regulation vs. temperature (MIC28304 - 1) vin = 12v v out = 5.0v i out = 0a to 3a f sw = 600khz 06 0 0 0 0 0 00 0 0 0 0 0 06 0 0 0 0 0 00 line regulation (%) temperature ( c) line regulation vs. temperature (MIC28304 - 1) vin = 7v to 70v v out = 5.0v i out = 0a f sw = 600khz 06 0 0 0 0 0 00 0 0 0 0 0 06 0 0 0 0 0 00 line regulation (%) temperature ( c) line regulation vs. temperature (MIC28304 - 1) vin = 7v to 70v v out = 5.0v i out = 3a f sw = 600khz 0
micrel, inc. MIC28304 typical characteristics (continued) 0.792 0.796 0.800 0.804 0.808 0.0 0.5 1.0 1.5 2.0 2.5 3.0 feedback voltage (v) output current (a) feedback voltage vs. output current (MIC28304 - 1) vin = 12v v out = 5.0v f sw = 600khz -3.0% -2.5% -2.0% -1.5% -1.0% -0.5% 0.0% 0.5% 1.0% 0.0 0.5 1.0 1.5 2.0 2.5 3.0 line regulation (%) output current (a) line regulation vs. output current (MIC28304 - 1) vin = 12v to 75v v out = 5.0v f sw = 600khz 10 20 30 40 50 60 70 80 90 100 0.01 0.1 1 10 efficiency (%) output current (a) efficiency (vin = 12v) vs. output current (MIC28304 - 1) 5.0v 3.3v 2.5v 1.8v 1.2v 0.8v f sw = 600khz ccm 10 20 30 40 50 60 70 80 90 100 0.01 0.1 1 10 efficiency (%) output current (a) efficiency (vin = 18v) vs. output current (MIC28304 - 1) 5.0v 3.3v 2.5v 1.8v 1.2v 0.8v f sw = 600khz ccm 10 20 30 40 50 60 70 80 90 100 0.01 0.1 1 10 efficiency (%) output current (a) efficiency (vin = 24v) vs. output current (MIC28304 - 1) 5.0v 3.3v 2.5v 1.8v 1.2v 0.8v f sw = 600khz ccm 10 20 30 40 50 60 70 80 90 100 0.01 0.1 1 10 efficiency (%) output current (a) efficiency (vin = 38v) vs. output current (MIC28304 - 1) 5.0v 3.3v 2.5v 1.8v 1.2v 0.8v f sw = 600khz ccm 10 20 30 40 50 60 70 80 90 100 0.01 0.1 1 10 efficiency (%) output current (a) efficiency (vin = 48v) vs. output current (MIC28304 - 1) 5.0v 3.3v 2.5v 1.8v 1.2v 0.8v f sw = 600khz ccm 10 20 30 40 50 60 70 80 90 100 0.01 0.1 1 10 efficiency (%) output current (a) efficiency (vin = 70v) vs. output current (MIC28304 - 1) 5.0v 3.3v 2.5v 1.8v 1.2v 0.8v f sw = 600khz ccm 50 55 60 65 70 75 80 85 90 95 100 0.01 0.1 1 10 efficiency (%) output current (a) efficiency vs. output current (MIC28304 - 1) v out = 12v f sw = 600khz ccm r3 = 23.2k
micrel, inc. MIC28304 typical characteristics (continued) 0 10 20 30 40 50 5 10 15 20 25 30 35 40 45 50 55 60 65 70 supply current (ma) input voltage (v) vin operating supply current vs. input voltage (MIC28304 - 2) v out = 5v i out = 0a f sw = 600khz 0.792 0.796 0.800 0.804 0.808 0.812 7 12 17 22 27 32 37 42 47 52 57 62 67 feedback voltage (v) input voltage (v) feedback voltage vs. input voltage (MIC28304 - 2) v out = 5.0v i out = 0a f sw = 600khz -1.0% -0.8% -0.6% -0.4% -0.2% 0.0% 0.2% 0.4% 0.6% 0.8% 1.0% 7 12 17 22 27 32 37 42 47 52 57 62 67 output regulation (%) input voltage (v) output regulation vs. input voltage (MIC28304 - 2) v out = 5.0v i out = 0a to 3a f sw = 600khz 0 5 10 15 20 25 30 35 40 45 50 5 10 15 20 25 30 35 40 45 50 55 60 65 70 shutdown current (a) input voltage (v) vin shutdown current vs. input voltage v en = 0v r16 = open f sw = 600khz 0 6 0 6 6 vdd voltage (v) input voltage (v) pvdd voltage vs. input voltage v out = 5.0v f sw = 600khz i pvdd = 10ma i pvdd = 40ma 0 2 4 6 8 10 7 12 17 22 27 32 37 42 47 52 57 62 67 current limit (a) input voltage (v) output peak current limit vs. input voltage v out = 5.0v f sw = 600khz 400 450 500 550 600 650 700 750 800 7 12 17 22 27 32 37 42 47 52 57 62 67 switching frequency (khz) input voltage (v) switching frequency vs. input voltage v out = 5.0v i out = 2a 0.00 0.30 0.60 0.90 1.20 1.50 5 10 15 20 25 30 35 40 45 50 55 60 65 70 enable threshold (v) input voltage (v) enable threshold vs. input voltage falling rising f sw = 600khz 0 1 2 3 4 5 6 7 8 9 10 -50 -25 0 25 50 75 100 125 shutdown current (a) temperature ( c) vin shutdown current vs. temperature vin = 12v v en = 0v i out = 0a f sw = 600khz 0 0
micrel, inc. MIC28304 typical characteristics (continued) 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 -50 -25 0 25 50 75 100 125 pvdd voltage (v) temperature ( c) pvdd voltage vs. temperature vin = 12v i out = 0a f sw = 600khz i pvdd = 40ma i pvdd = 10ma 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4.0 4.1 4.2 4.3 4.4 -50 -25 0 25 50 75 100 125 vdd threshold (v) temperature ( c) pvdd uvlo threshold vs. temperature rising falling v in = 12v i out = 0a f sw = 600khz 0 2 4 6 8 10 -50 -25 0 25 50 75 100 125 current limit (a) temperature ( c) output peak current limit vs. temperature vin = 12v v out = 5.0v f sw = 600khz 0 20 40 60 80 100 -50 -25 0 25 50 75 100 125 en bias current (a) temperature ( c) en bias current vs. temperature vin = 12v v en = 0v f sw = 600khz 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 -50 -25 0 25 50 75 100 125 enable threshold (v) temperature ( c) enable threshold vs. temperature falling rising vin = 12v v out = 5v f sw = 600khz 0 4 8 12 16 20 24 28 32 36 40 -50 -25 0 25 50 75 100 125 supply current (ma) temperature ( c) vin operating supply current vs. temperature (MIC28304 - 2) vin = 12v v out = 5.0v i out = 0a f sw = 600khz 0.792 0.796 0.800 0.804 0.808 0.812 -50 -25 0 25 50 75 100 125 feeback voltage (v) temperature ( c) feedback voltage vs. temperature (MIC28304 - 2) v in = 12v v out = 5.0v i out = 0a f sw = 600khz -0.3% -0.2% -0.1% 0.0% 0.1% 0.2% 0.3% 0.4% -50 -25 0 25 50 75 100 125 load regulation (%) temperature ( c) load regulation vs. temperature (MIC28304 - 2) vin = 12v v out = 5.0v i out = 0a to 3a f sw = 600khz -1.00% -0.50% 0.00% 0.50% 1.00% -50 -25 0 25 50 75 100 125 line regulation (%) temperature ( c) line regulation vs. temperature (MIC28304 - 2) vin = 7v to 70v v out = 5.0v i out = 0a f sw = 600khz march 25, 2014 11 revision 1.1
micrel, inc. MIC28304 typical characteristics (continued) -1.0% -0.5% 0.0% 0.5% 1.0% -50 -25 0 25 50 75 100 125 line regulation (%) temperature ( c) line regulation vs. temperature (MIC28304 - 2) vin = 7v to 70v v out = 5.0v i out = 3a f sw = 600khz 100 150 200 250 300 350 400 450 500 550 600 650 700 -50 -25 0 25 50 75 100 125 switching frequency (khz) temperature ( c) switching frequency vs. temperature (MIC28304 - 2) vin = 12v v out = 5v i out = 0a 0.792 0.796 0.800 0.804 0.808 0.0 0.5 1.0 1.5 2.0 2.5 3.0 feedback voltage (v) output current (a) feedback voltage vs. output current (MIC28304 - 2) vin = 12v v out = 5.0v f sw = 600khz 0.0% 0.1% 0.1% 0.2% 0.2% 0.3% 0.3% 0.4% 0.4% 0.0 0.5 1.0 1.5 2.0 2.5 3.0 line regulation (%) output current (a) line regulation vs. output current (MIC28304 - 2) vin = 12v to 70v v out = 5.0v f sw = 600khz 30 40 50 60 70 80 90 100 0 0.5 1 1.5 2 2.5 3 3.5 4 efficiency (%) output current (a) efficiency (vin =12v) vs. output current (MIC28304 - 2) 5.0v 3.3v 2.5v 1.8v 1.2v 0.8v f sw = 600khz 30 40 50 60 70 80 90 100 0 0.5 1 1.5 2 2.5 3 3.5 4 efficiency (%) output current (a) efficiency (vin = 18v) vs. output current (MIC28304 - 2) 5.0v 3.3v 2.5v 1.8v 1.2v 0.8v f sw = 600khz 30 40 50 60 70 80 90 100 0 0.5 1 1.5 2 2.5 3 3.5 4 efficiency (%) output current (a) efficiency (vin = 24v) vs. output current (MIC28304 - 2) 5.0v 3.3v 2.5v 1.8v 1.2v 0.8v f sw = 600khz 30 40 50 60 70 80 90 100 0 0.5 1 1.5 2 2.5 3 3.5 4 efficiency (%) output current (a) efficiency (vin = 38v) vs. output current (MIC28304 - 2) 5.0v 3.3v 2.5v 1.8v 1.2v 0.8v f sw = 600khz 30 40 50 60 70 80 90 100 0 0.5 1 1.5 2 2.5 3 3.5 4 efficiency (%) output current (a) efficiency (vin = 48v) vs. output current (MIC28304 - 2) 5.0v 3.3v 2.5v 1.8v 1.2v 0.8v f sw = 600khz march 25, 2014 12 revision 1.1
micrel, inc. MIC28304 typical characteristics (continued) * case temperature : the temperature measurement was taken at the hottest point on the MIC28304 case mounted on a 5 square inch pcb (see thermal measurement section). actual results will depend upon the size of the pcb, ambient temperature and proximity to other heat - emitting components. 30 40 50 60 70 80 90 100 0 0.5 1 1.5 2 2.5 3 3.5 4 efficiency (%) output current (a) efficiency (vin = 70v) vs. output current (MIC28304 - 2) 5.0v 3.3v 2.5v 1.8v 1.2v 0.8v f sw = 600khz 0 20 40 60 80 100 120 140 0.0 0.5 1.0 1.5 2.0 2.5 3.0 die temperature ( c) output current (a) die temperature* (vin = 12v) vs. output current (MIC28304 - 2) vin = 12v v out = 5.0v f sw = 600khz 0 20 40 60 80 100 120 140 0.0 0.5 1.0 1.5 2.0 2.5 3.0 die temperature ( c) output current (a) die temperature* (vin = 48v) vs. output current (MIC28304 - 2) vin = 48v v out = 5.0v f sw = 600khz ` 0 20 40 60 80 100 120 140 0.0 0.5 1.0 1.5 2.0 2.5 3.0 die temperature ( c) output current (a) die temperature* (vin = 70v) vs. output current (MIC28304 - 2) vin = 70v v out = 5.0v f sw = 600khz 0 100 200 300 400 500 600 700 800 10.00 100.00 1000.00 10000.00 sw freq (khz) r19 (k ohm) switching frequency v out = 5v i out = 2a vin =48v vin = 12v 0 0.5 1 1.5 2 2.5 0 1 2 3 ic power dissipation (w) output current (a) ic power dissipation vs. output current (MIC28304 - 2) vin = 12v f sw = 600khz v out = 5v v out = 0.8v v out = 5v, 3.3v, 2.5v, 1.8v, 1.2v, 0.8v 0 0.5 1 1.5 2 2.5 3 3.5 0 1 2 3 ic power dissipation (w) output current (a) ic power dissipation vs. output current (MIC28304 - 2) vin = 24v f sw = 600khz v out = 5v v out = 0.8v v out = 5v, 3.3v, 2.5v, 1.8v, 1.2v, 0.8v 0 1 2 3 4 5 6 0 1 2 3 ic power dissipation (w) output current (a) ic power dissipation vs. output current (MIC28304 - 2) vin = 48v f sw = 600khz v out = 5v v out = 0.8v v out = 5v, 3.3v, 2.5v, 1.8v, 1.2v, 0.8v 0 1 2 3 4 5 6 7 8 9 0 1 2 3 ic power dissipation (w) output current (a) ic power dissipation vs. output current (MIC28304 - 2) vin = 70v f sw = 600khz v out = 5v v out = 0.8v v out = 5v, 3.3v, 2.5v, 1.8v, 1.2v, 0.8v march 25, 2014 13 revision 1.1
micrel, inc. MIC28304 typical characteristics (continued) 0 1 2 3 25 40 55 70 85 100 load current (a) maximum ambient temperature ( v out = 5v f sw = 600khz MIC28304 - 2 t j_max = 125 c vin = 18v vin = 12v vin = 24v vin = 48v 0 1 2 3 25 40 55 70 85 100 load current (a) maximum ambient temperature ( v out = 3.3v f sw = 600khz MIC28304 - 2 t j_max = 125 c vin = 18v vin = 12v vin = 24v vin = 48v 0 1 2 3 25 40 55 70 85 100 load current (a) maximum ambient temperature ( v out = 2.5v f sw = 600khz MIC28304 - 2 t j_max = 125 c vin =18v vin = 12v vin = 24v vin = 48v 0 1 2 3 25 40 55 70 85 100 load current (a) maximum ambient temperature ( v out = 1.8v f sw = 600khz MIC28304 - 2 t j_max =125 c vin = 12v vin = 24v vin = 48v vin =18v 0 1 2 3 25 40 55 70 85 100 load current (a) maximum ambient temperature ( v out = 1.2v f sw = 600khz MIC28304 - 2 t j_max =125 c vin = 12v vin = 24v vin = 48v vin =18v 0 1 2 3 25 40 55 70 85 100 load current (a) maximum ambient temperature ( v out = 0.8v f sw = 600khz MIC28304 - 2 t j_max =125 c vin =18v vin = 12v vin = 48v vin = 24v 0 1 2 3 25 40 55 70 85 100 load current (a) maximum ambient temperature ( c) thermal derating v out = 12v f sw = 600khz MIC28304 - 2 r3 = 23.2k t j_max =125 c 48vin 18vin vin = 48v vin = 24v 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 ic power dissipation (w) output current (a) ic power dissipation vs. output current (MIC28304 - 2) v out = 12v 5 n f sw = 600khz 70vin 48vin 36vin 24vin 18vin 50 55 60 65 70 75 80 85 90 95 100 0 0.6 1.2 1.8 2.4 3 3.6 efficiency (%) output current (a) efficiency vs. output current (MIC28304 - 2) v out = 12v f sw = 600khz 5 n 18vin 24vin 36vin 48vin 70vin march 25, 2014 14 revision 1.1
micrel, inc. MIC28304 functional characteristics ? march 25, 2014 15 revision 1.1
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micrel, inc. MIC28304 functional characteristics march 25, 2014 20 revision 1.1
micrel, inc. MIC28304 functional diagram march 25, 2014 21 revision 1.1
micrel, inc. MIC28304 functional description the MIC28304 is an adaptive on - time synchronous buck regulator module built for high - input voltage to low - output voltage conversion applications. the MIC28304 is designed to operate over a wide input voltage range, from 4.5v to 70v, and the output is adju stable with an external resistor divider. an adaptive on - time control scheme is employed to obtain a constant switching frequency and to simplify the control compensation. hiccup mode over - current protection is implemented by sensing low - side mosfet?s r ds(on) . the device features internal soft - start, enable, uvlo, and thermal shutdown. the module has integrated switching fets, inductor, bootstrap diode, resistor and capacitor. theory of operation per the functional diagram of the MIC28304 module , t he output voltage is sensed by the MIC28304 feedback pin fb via the voltage divider r1 and r11, and compared to a 0.8v reference voltage vref at the error c omparator through a low - gain transconductance (gm) amplifier. if the feedback voltage decreases and the amplifier output is below 0.8v, then the error comparator will trigger the control logic and generate an on - time period. the on - time period length is pr edetermined by the ?fixed ton estimator? circuitry: sw in out ) estimated ( on f v v t = the maximum duty cycle is obtained from the 200ns t off(min) : s s ) min ( off s max t ns 200 1 t t t d ? = ? =
micrel, inc. MIC28304 figure 1 . MIC28304 control loop timing figure 2 shows the operation of the MIC28304 during a load transient. the output voltage drops due to the sudden load increase, which causes the v fb to be less than v ref . this will cause the error comparator to trigger an on - time period. at the end of the on - time period, a minimum off - time t off(min) is generated to charge the bootstrap capacitor (c bst ) since the feedback voltage is still below v ref . then, the next on - time period is triggered due to the low feedback voltage. therefore, the switching frequency changes during the load transient, but returns to the nominal fixed frequency once the output has stabilized at the new load c urrent level. with the varying duty cycle and switching frequency, the output recovery time is fast and the output voltage deviation is small. figure 2 . MIC28304 load transient response unlike true current - mode control, the mi c28304 uses the output voltage ripple to trigger an on - time period. the output voltage ripple is proportional to the inductor current ripple if the esr of the output capacitor is large enough. in order to meet the stability requirements, the MIC28304 feedb ack voltage ripple should be in phase with the inductor current ripple and are large enough to be sensed by the g m amplifier and the error comparator. the recommended feedback voltage ripple is 20mv~100mv over full input voltage range. if a low esr output capacitor is selected, then the feedback voltage ripple may be too small to be sensed by the g m amplifier and the error comparator. also, the output voltage ripple and the feedback voltage ripple are not necessarily in phase with the inductor current rippl e if the esr of the output capacitor is very low. in these cases, ripple injection is required to ensure proper operation. please refer to ?ripple injection? subsection in application information for more details about the ripple injection technique. discontinuous mode (MIC28304 - 1 only) in continuous mode , the inductor current is always greater than zero; however, at light loads , the MIC28304 - 1 is able to force the inductor current to operate in discontinuous mode. discontinuous mode is where the inductor current falls to zero , as indicated by trace (i l ) shown in figure 3 . during this period , the efficiency is optimized by shutting down all the non - essential circuits and minimizing the supply current. the MIC28304 - 1 wakes up and turns on the high - side mosfet when the feedback voltage v fb drop s below 0.8v. the MIC28304 - 1 has a zero c ross ing c omparator (zc) that monitors the inductor current by sensing the voltage drop across the low - side mosfet during its on - time. if the v fb > 0.8v and the inductor current goes slightly negative, then the MIC28304 - 1 automatically powers down most of the ic circuitry and goes into a low - power mode. once the MIC28304 - 1 goes into discontinuous mode, both dl and dh are low, which turns off the high - side and low - side mosfets. the load current is supplied by the output capacitors and v out drops. if the drop of v out causes v fb to go below v ref , then all the circuits will wake up into normal continuous mode. first , the b ias currents of most circuits reduced during the discontinuous mode are restored, and then a t on pulse is triggered before the drivers are turned on to avoid any possible glitches. finally, the high - side driver is turned on. figure 3 shows the control loop timing in discontinuous mode. march 25, 2014 23 revision 1.1
micrel, inc. MIC28304 figure 3 . mic28302 - 1 control loop timing (discontinuous mode) during discontinuous mode, the bias current of most circuits is substantially reduced. as a result, the total power supply current during discontinuous mode is only about 400 a, allowing the MIC28304 - 1 to achieve high efficiency in light load applications. soft - start soft - start reduces the input power supply surge current at startup by controlling the output voltage rise time. the input surge appears while the output capacitor is charged up. a slower output rise time will draw a lower input surge current. the MIC28304 implements an internal digital soft - start by making the 0.8v reference voltage v ref ramp from 0 to 100% in about 5ms with 9.7mv steps. therefore, the output voltage is controlled to increase slowly by a stair - case v fb ramp. once the soft - start cycle ends, the related circuitry is disabled to reduce current consumption. pvdd must be powered up at the same time or after v in to make the soft - start function correctly. current limit the MIC28304 uses the r ds(on) of the low side mosefet and external resistor connected from ilim pin to sw node to decide the current limit. figure 4 . MIC28304 current - limiting circuit in each switching cycle of the MIC28304, the inductor current is sensed by monitoring the low - side mosfet in the off pe riod. the sensed voltage v(ilim) is compared with the power ground (pgnd) after a blanking time of 150ns . in this way the drop voltage over the resistor r15 (vcl) is compared with the drop over the bottom fet generating the short current limit. the small capacitor (c6) connected from ilim pin to pgnd filters the switching node ringing during the o ff- time allowing a better short limit measurement. the time constant created by r15 and c6 should be much less than the minimum off time. the v cl drop allows prog ramming of short limit through the value of the resistor (r15), if the absolute value of the voltage drop on the bottom fet is greater than v cl . in that case the v(ilim) is lower than pgnd and a short circuit event is triggered. a hiccup cycle to treat the short event is generated. the hiccup sequence including the soft start reduces the stress on the switching fets and protects the load and supply for severe short conditions. march 25, 2014 24 revision 1.1
micrel, inc. MIC28304 the short - circuit current limit can be programmed by using equation 3 . ( ) + ? ? = typically v cl = current - limit threshold ( typical absolute value is 14mv per the electrical ch aracteristics (4) ) i cl = current - limit source current ( typical value is 80a , per the electrical characteristics table) . ? i l(pp) = inductor current peak - to - peak, since the inductor is integrated use equation 4 to calculate the inductor ripple current. the peak - to - peak inductor current ripple is: l f v ) v (v v i sw in(max) out in(max) out l(pp) ? = ? ? in case of hard short, the short limit is folded down to allow an indefinite hard short on the output without any destructive effect. it is mandatory to make sure that the inductor current used to charg e the output capacitance during soft start is under the folded short limit; otherwise the supply will go in hiccup mode and may not be finishing the soft start successfully. the mosfet r ds(on) varies 30 % to 40% with temperature; therefore, it is recomme nded to add a 50% margin to i clim in equation 3 to avoid false current limiting due to increased mosfet junction temperature rise. table 2 shows typic al output current limit value for a given r15 with c6 = 10pf. table 2 . typical output current - limit value r15 typical output current limit 1.81k 3a 2.7k 6.3a march 25, 2014 25 revision 1.1
micrel, inc. MIC28304 application information simplified input transient circuitry the 76v absolute maximum rating of MIC28304 allows simplifying the transient voltage suppressor on the input supply side which is very common in industrial applications. the input supply voltage v in figure 5 may be operating at 12v input rail most of the time, but can encounter noise spike of 60v for a short duration. by using MIC28304, which has 76v absolute maximum voltage rating, the input tra nsient suppressor is not needed. which saves on component count, form factor, and ultimately the system becomes less expensive. figure 5 . simplified input transient circuitry setting the switching frequency the MIC28304 switching frequency can be adjusted by changing the value of resistor r1 9 . the top resistor of 100k is internal to module and is connected between vin and freq pin, so the value of r19 sets the switching frequency. the switching frequency also depends upo n vin, v out and load conditions. figure 6 . switching frequency adjustment equation 5 gives the estimated switching frequency: : u k 100 19 r 19 r f f o adj _ sw eq. 5 where: f o = switching f requency when r19 is open for more precise setting, it is recommended to use figure 7 : figure 7 . switching frequency vs. r19 output capacitor selection the type of the output capacitor is usually determined by the application and its equivalent ser ies resistance (esr). voltage and rms current capability are two other important factors for selecting the output capacitor. recommended capacitor types are mlcc, tantalum, low - esr aluminum electrolytic, os - con and poscap. the output capacitor?s esr is usu ally the main cause of the output ripple. the MIC28304 requires ripple injection and t he output capacitor esr e ffects the control loop from a stability point of view. 0 100 200 300 400 500 600 700 800 10.00 100.00 1000.00 10000.00 sw freq (khz) r19 (k ohm) switching frequency v out = 5v i out = 2a vin =48v vin = 12v march 25, 2014 26 revision 1.1
micrel, inc. MIC28304 the maximum value of esr is calculated as in equation 6 : l(pp) out(pp) c i v esr out d eq. 6 where: ? v out(pp) = peak - to - peak output voltage ripple i l(pp) = peak - to - peak inductor current ripple the total output ripple is a combination of the esr and output capacitance. the total ripple is calculated in equation 7 : 2 c l(pp) 2 sw out l(pp) out(pp) out esr i 8 f c i v + = functional description , the MIC28304 requires at least 20mv peak - to - peak ripple at the fb pin to make the g m amplifier and the error comparator behave properly. also, the output voltage ripple should be in phase with the inductor current. therefore, the output voltage ripple caused by the output capacitors value should be much smaller than the ripple caused by t he output capacitor esr. if low - esr capacitors, such as ceramic capacitors, are selected as the output capacitors, a ripple injection method should be applied to provide enough feedback voltage ripple. please refer to the ?ripple injection? subsection for more details. the voltage rating of the capacitor should be twice the output voltage for a tantalum and 20% greater for aluminum electrolytic or os - con. the output capacitor rms current is calculated in equation 8 : 12 i i l(pp) (rms) c out eq. 8 the pow er dissipated in the output capacitor is: out out out c 2 (rms) c ) diss(c esr i p u eq. 9 input capacitor selection the input capacitor for the power stage input pv in should be selected for ripple current rating and voltage rating. tantalum input capacitors may fail when subjected to high inrush currents, caused by turning the input supply on. a tantalum input capacitor?s voltage rating should be at least two times the maximum input voltage to maximize reliability. aluminum electrolytic, os - con, and multilayer polymer film capacitors can handle the higher inrush currents without voltage de - rating. the input voltage ripple will primarily depend on the input capacitor?s e sr. the peak input current is equal to the peak inductor current, so: v in = i l(pk) esr cin eq. 10 the input capacitor must be rated for the input current ripple. the rms value of input capacitor current is determined at the maximum output current. as suming the peak - to - peak inductor current ripple is low: d) (1 d i i out(max) cin(rms) u u | eq.11 the power dissipated in the input capacitor is: p diss(cin) = i cin(rms) 2 esr cin eq. 1 2 the general rule is to pick the capacitor with a ripple current rating equal to or greater than the calculated worst (v in_max ) case rms capacitor current. its voltage rating should be 20% to 50% higher than the maximum input voltage. typically the input ri pple (dv) needs to be kept down to less than 10% of input voltage. the esr also increases the input ripple. march 25, 2014 27 revision 1.1
micrel, inc. MIC28304 equation 13 should be used to calculate the input capacitor. also it is recommended to keep some margin on the calculated value: dv f ) d 1 ( i c sw out(max) in ? output voltage setting components the MIC28304 requires two resistors to set the output voltage as shown in figure 8 : figure 8 . voltage - divider configuration the output voltage is determined by equation 14: ? ? ? ? ? ? + = 11 1 1 v v fb out r r eq. 14 where: v fb = 0.8v a typical value of r1 used on the standard evaluation board is n ,i5lvwrrodujhlwpd\doorzqrlvhwreh introduced into the voltage feedback loop. if r1 is too small in value, it will decrease the efficiency of the power supply, especially at light loads. once r1 is s elected, r 11 can be calculated using equation 15 : fb out fb v v r1 v r11 ? = ripple injection the v fb ripple required for proper operation of the MIC28304 g m amplifier and error comparator is 20mv to 100mv. however, the output voltage ripple is generally designed as 1% to 2% of the output voltage. for a low output voltage, such as a 1v, the output voltage ripple is only 10mv to 20mv, and the feedback voltage r ipple is less than 20mv. if the feedback voltage ripple is so small that the g m amplifier and error comparator cannot sense it, then the MIC28304 will lose control and the output voltage is not regulated. in order to have some amount of v fb ripple, a rippl e injection method is applied for low output voltage ripple applications. the table 2 summarizes the ripple injection component values for ceramic output capacitor. the applications are divided into three situations according to the amount of the feedback voltage ripple: 1. enough ripple at the feedback voltage due to the large esr of the output capacitors ( figure 9 ): figure 9 . enough ripple at fb as shown in figure 10 , the converter is stabl e without any ripple injection. figure 10 . inadequate ripple at fb march 25, 2014 28 revision 1.1
micrel, inc. MIC28304 the feedback voltage ripple is: l(pp) c fb(pp) i esr r11 r1 r11 v out u u eq. 16 where: ?, l(pp) = t he peak - to - peak value of the inductor current ripple 2. inadequate ripple at the feedback voltage due to the small esr of the output capacitors , such is the case with ceramic output capacitor . the output voltage ripple is fed into the fb pin through a feed - forward capacitor c ff in this situation, as shown in figure 11 . the typical c ff value is between 1nf and 100nf. figure 11 . invisible ripple at fb with the feed - forward capacitor, the feedback voltage ripple is very close to the output voltage ripple: l(pp) fb(pp) ?, esr ?9 u | eq. 17 3. virtually no ripple at the fb pin voltage due to the very - lo w esr of the output capacitors. in this situation, the output voltage ripple is less than 20mv. therefore, additional ripple is injected into the fb pin from the switching node sw via a resistor r inj and a capacitor c inj , as shown in figure 11 . the injected ripple is: w u u u u u sw div in fb(pp) f 1 d) - (1 d k v ?9 eq. 18 r1//r11 r r1//r11 k inj div eq. 19 where : v in = p ower stage input voltage d = duty cycle f sw = switching frequency w = (r1// r 11 //r inj ) u c ff in equations 18 and 19 , it is assumed that the time constant associated with c ff must be much greater than the switching period: 1 t f 1 sw u w w eq. 20 if the voltage divider resistors r1 and r 11 duhlqwkhn range, then a c ff of 1nf to 100nf can easily satisfy the large time constant requirements. also, a 100nf injection capacitor c inj is used in order to be considered as short for a wide range of the frequencies. the process of sizing the ripple injection resistor and capaci tors is: step 1. select c ff to feed all output ripples into the feedback pin and make sure the large time constant assumption is satisfied. typical choice of c ff is 1nf to 100nf if r1 and r 11 duhlqn udqjh step 2. select r inj according to the expected f eedback voltage ripple using equation 2 2 : d) (1 d f v ?9 k sw in fb(pp) div u u u w eq. 21 then the value of r inj is obtained as: 1) k 1 ( (r1//r11) r div inj u eq. 22 step 3. select c inj as 100nf, which could be considered as short for a wide range of the frequencies. table 3 summarizes t he typical value of components for particular input and output voltage, and 600khz switching frequency design, for details refer to the b ill of materials section. march 25, 2014 29 revision 1.1
micrel, inc. MIC28304 table 3 . recomme nded component values for 600khz switching frequency v out vin r3 (r inj ) r1 (top feedback resistor ) r11 (bottom feedback resistor ) r19 c10 (c inj ) c12 (c ff ) c out 0.9v 5v to 70v 16.5k 10k 80.6k dnp 0.1f 2.2nf 47f/6.3v or 2 x 22f 1.2v 5v to 70v 16.5k 10k 20k dnp 0.1f 2.2nf 47f/6.3v or 2 x 22f 1.8v 5v to 70v 16.5k 10k 8.06k dnp 0.1f 2.2nf 47f/6.3v or 2 x 22f 2.5v 5v to 70v 16.5k 10k 4.75k dnp 0.1f 2.2nf 47f/6.3v or 2 x 22f 3.3v 5v to 70v 16.5k 10k 3.24k dnp 0.1f 2.2nf 47f/6.3v or 2 x 22f 5v 7v to 70v 16.5k 10k 1.9k dnp 0.1f 2.2nf 47f/6.3v or 2 x 22f 12v 18v to 70v 23.2k 10k 715 dnp 0.1f 2.2nf 47f/16v or 2 x 22f thermal measurements and safe operating area measuring the ic?s case temperature is recommended to ensure it is within its operating limits. although this might seem like a very elementary task, it is easy to get erroneous results. the most common mistake is to use the standard thermal couple that co mes with a thermal meter. this thermal couple wire gauge is large, typically 22 gauge, and behaves like a heatsink, resulting in a lower case measurement. two methods of temperature measurement are using a smaller thermal couple wire or an infrared thermom eter. if a thermal couple wire is use d, it must be constructed of 36- gauge wire or higher (smaller wire size) to minimize the wire heat - sinking effect. in addition, the thermal couple tip must be covered in either thermal grease or thermal glue to make sur e that the thermal couple junction is making good contact with the case of the ic. omega brand thermal couple (5sc - tt - k - 36- 36) is adequate for most applications. wherever possible, an infrared thermometer is recommended. the measurement spot size of most infrared thermometers is too large for an accurate reading on a small form factor ics. however, an ir thermometer from optris has a 1mm spot size, which makes it a good choice for measuring the hottest point on the case. an optional stand makes it easy to hold the beam on the ic for long periods of time. the safe operating a rea (soa) of the MIC28304 is shown in the typical characteristics 275khz switching frequency section . these t hermal measurements were taken on MIC28304 evaluation board. since the MIC28304 is an entire system comprised of s witching regulator c ontroller, mosfets and i nductor, the part needs to be considered as a system. the soa curves will give guidance to reasonable use of the MIC28304. emission characteristics of MIC28304 the MIC28304 integrates switching components in a single package, so the MIC28304 has reduced emission compared to standard buck regulator with exte rnal mosfets and inductors. the radiated emi scans for MIC28304 are shown in the typical characteristics section . the lim it on the graph is per en5502 2 c lass b standard. march 25, 2014 30 revision 1.1
micrel, inc. MIC28304 pcb layout guidelines warning: to minimize emi and output noise, follow these layout recommendations. pcb l ayout is critical to achieve reliable, stable and efficient performance. a ground plane is required to control emi and minimize the inductance in power, signal and return paths. the following figures optimized from small form factor point of view shows top and bottom layer of a four layer pcb . it is recommended to use mid layer 1 as a continuous ground plane. figure 12 . top and b ottom layer of a four - layer board the following guidelines should be followed to insure proper oper ation of the MIC28304 converter: ic ? the analog ground pin (gnd) must be connected directly to the ground planes. do no t route the gnd pin to the pgnd pin on the top layer. ? place the ic close to the point of load (pol). ? use fat traces to route the input and output power lines. ? analog and power grounds should be kept separate and connected at only one location. input capacitor ? place the input capacitors on the same side of the board and as close to the ic as possible. ? place several vias to the ground plane close to the input capacitor ground terminal. ? use either x7r or x5r dielectric input capacitors. do not use y5v or z5u type capacitors. ? do not replace the ceramic input capacitor with any other type of capacitor. any type of capacitor can be placed in parallel with the input capacitor. ? if a tantalum input capacitor is placed in parallel with the input capacitor, it mu st be recommended for switching regulator applications and the operating voltage must be derated by 50%. ? in ?hot - plug? applications, a tantalum or electrolytic bypass capacitor must be used to limit the over - voltage spike seen on the input supply with powe r is suddenly applied. rc snubber ? place the rc snubber on the same side of the board and as close to the sw pin as possible. sw node ? do not route any digital lines underneath or close to the sw node. ? keep the switch node (sw) away from the feedback (fb) pin. output capacitor ? use a wide trace to connect the output capacitor ground terminal to the input capacitor ground terminal. ? phase margin will change as the output capacitor value and esr changes. contact the factory if the output capacitor is different from what is shown in the bom. ? the feedback trace should be separate from the power trace and connected as close as possible to the output capacitor. sensing a long high - current load trace can degrade the dc load regulation. march 25, 2014 31 revision 1.1
micrel, inc. MIC28304 evaluation board schematic s figure 13 . schematic of MIC28304 evaluation board (j1, j8, j10, j11, j12, j13, r14, r20, and r21 are for testing purposes) march 25, 2014 32 revision 1.1
micrel, inc. MIC28304 evaluation board schematics (continued) figure 14 . schematic of MIC28304 evaluation board (optimized for smallest footprint) march 25, 2014 33 revision 1.1
micrel, inc. MIC28304 bill of materials item part number manufacturer description qty . c1 eeu - fc2a101 panasonic ( 6 ) 100f aluminum capacitor, 100v 1 c2, c3 grm32er72a225k murata ( 7 ) 2.2f/100v ceramic capacitor, x7r, size 1210 2 c3225x7r2a225k tdk ( 8 ) 12101c225kat2a avx ( 9 ) c6 gcm1885c2a100ja16d murata 10pf, 100v, 0603, npo 1 06031a100jat2a avx c8 grm188r70j105ka01d murata 1f/6.3v ceramic capacitor, x7r, size 0603 1 06036c105kat2a avx c1608x5r0j105k tdk c9 grm21br72a474ka73 murata 0.47f/100v ceramic capacitor, x7r, size 0805 1 08051c474kat2a avx c10, c17 grm188r72a104ka35d murata 0.1f/100v ceramic capacitor, x7r, size 0603 2 c1608x7s2a104k tdk 0.1f/100v, x7s, 0603 c11 grm188r72a102ka01d murata 1nf/100v ceramic capacitor, x7r, size 0603 1 06031c102kat2a avx c1608x7r2a102k tdk c12 grm188r72a222ka01d murata 2.2nf/100v ceramic capacitor, x7r, size 0603 1 06031c222kat2a avx c1608x7r2a222k tdk c14 grm31cr60j476me19k murata 47f/6.3v ceramic capacitor, x5r, size 1210 1 12106d476mat2a avx c16 grm188r71h104ka93d murata 0.1f/6.3v ceramic capacitor, x7r, size 0603 1 06035c104kat2a avx c1608x7r1h104k tdk c4, c5, c7, c13, c15 dnp notes: 6. panasonic: www.panasonic.com . 7. murata: www.murata.com . 8. tdk: www.tdk.com . 9. avx: www.avx.com . march 25, 2014 34 revision 1.1
micrel, inc. MIC28304 bill of materials (continued) item part number manufacturer description qty . r1 crcw060310k0fkea vishay dale ( 10 ) 10k resistor, size 0603, 1% 1 r2 crcw08051r21fkea vishay dale 1.21 resistor, size 0805, 5% 1 r3 crcw06031652f vishay dale 16.5k resistor, size 0603, 1% 1 r10 crcw06033k24fkea vishay dale 3.24k resistor, size 0603, 1% 1 r11 crcw06031k91fkea vishay dale 1.91k resistor, size 0603, 1% 1 r12 crcw0603715r0fkea vishay dale 715 resistor, size 0603, 1% dnp r14, r20 crcw06030000fkea vishay dale 0 resistor, size 0603, 5% 2 r15 crcw04022k70jned vishay dale 2.7k resistor, size 0603, 1% 1 r16 crcw0603100kfkeahp vishay dale 1 00k? resistor, size 0603, 1% 1 r18 crcw060349k9fkea vishay dale 49.9 k resistor, size 0603, 1% 1 r21 crcw060349r9fkea vishay dale 49.9 resistor, size 0603, 1% 1 r23 crcw06031r21fkea vishay dale 1.21? resistor, size 0603, 1% 1 r4, r19 dnp all reference designators ending with ?a? open u1 MIC28304 - 1ym p micrel, inc. ( 11) 70v, 3a power module hyper speed control family 1 MIC28304 - 2ym p notes: 10. vishay: www.vishay.com . 11. micrel, inc.: www.micrel.com . march 25, 2014 35 revision 1.1
micrel, inc. MIC28304 pcb layout recommendations evaluation board top layer evaluation board mid - layer 1 (ground plane) march 25, 2014 36 revision 1.1
micrel, inc. MIC28304 pcb layout recommendations (continued) evaluation board mid - layer 2 evaluation board bottom layer march 25, 2014 37 revision 1.1
micrel, inc. MIC28304 package information ( 12) 64- pin 12mm 12mm qfn ( mp ) note: 12. package information is correct as of the publication date. for updates and most current information, go to www.micrel.com . march 25, 2014 38 revision 1.1
micrel, inc. MIC28304 recommended land pattern 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 micrel?s terms and conditions of sale for such products, micrel assumes no liability whatsoever, and micrel disclaims any express or implied warranty relating to the sale and/or use of micrel products in cluding liability or warranties relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right . micrel products are not designed or authorized for use as components in life supp ort appliances, devices or systems where malfunction of a product can reasonably be expected to result in personal injury. life support devices or systems are devices or systems that (a) are intended for surgical implant into the body or (b) support or sus tain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. a purchaser?s use or sale of micrel products for use in life support appliances, devices or systems is a purchaser?s own risk a nd purchaser ag rees to fully indemnify micrel for any damages resulting from such use or sale. ? 20 14 micrel, incorporated. march 25, 2014 39 revision 1.1

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