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mic2230 dual synchronous 800ma/800ma step-down dc/dc regulator mlf and micro lead frame are registered trademarks of amkor technology, 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 april 2010 m9999-040810-c general description the mic2230 is dual output, high-efficiency synchronous step-down dc/dc converter. the mic2230 is ideally suited for portable systems which demand high power conversion efficiencies and fa st transient performance, while offered in a very small package. the mic2230 offers an ultra-low quiescent current in light load mode assuring minimum current draw from battery powered applications in standby modes. the mic2230 was designed to only require miniature 2.2h inductors and 10f ceramic capacitors. the mic2230 features a sele ctable mode that allows the user to trade-off lowest noise performance for low power efficiency. trickle mode tm operation provides ultra-high efficiency at light loads, while pwm operation provides very low ripple noise performanc e. to maximize battery life in low-dropout conditions, mic2230 can operate with a maximum duty cycle of 100%. the mic2230 is available in a space-saving 3mm 3mm mlf ? -12l package with a junction temperature range from C40 c to +125 c. data sheets and support documentation can be found on micrels web site at www.micrel.com. features ? high efficiency: over 96% ? ultra-low quiescent current: only 28a ? ultra-low shutdown current less than 1a ? fast transient performance ? 2.5mhz pwm operation ? high output current capability per channel: 800ma ? no schottky diodes required ? stable with 2.2h inductor, 10f ceramic capacitor ? adjustable output voltage down to 0.8v ? built-in soft-start circuitry ? current limit protection ? automatic switching into light load mode operation ? /fpwm pin allows low noise all-pwm mode operation ? power good output with internal 5a current source allows sequencing with programmable delay time ? small thermally enhanced 3mm 3mm mlf ? package applications ? cellular phones ? pdas ? digital cameras ? mp3 players ? pc cards ? wireless and dsl modems ___________________________________________________________________________________________________________ typical application downloaded from: http:///
micrel, inc. mic2230 april 2010 2 m9999-040810-c ordering information part number v out1 v out2 junction temperature range package lead finish mic2230-aayml adj. adj. C40 c to +125 c 12-pin 3mm x 3mm mlf ? pb-free mic2230-521yml 1.28v 1.65v C40 c to +125 c 12-pin 3mm x 3mm mlf ? pb-free mic2230-g4yml 1.8v 1.2v C40 c to +125 c 12-pin 3mm x 3mm mlf ? pb-free mic2230-gf9yml 1.8v 1.545v C40 c to +125 c 12-pin 3mm x 3mm mlf ? pb-free mic2230-gfhyml 1.8v 1.575v C40 c to +125 c 12-pin 3mm x 3mm mlf ? pb-free mic2230-gsyml 1.8v 3.3v C40 c to +125 c 12-pin 3mm x 3mm mlf ? pb-free mic2230-gwyml 1.8v 1.6v C40 c to +125 c 12-pin 3mm x 3mm mlf ? pb-free mic2230-j4yml 2.5v 1.2v C40 c to +125 c 12-pin 3mm x 3mm mlf ? pb-free mic2230-s4yml 3.3v 1.2v C40 c to +125 c 12-pin 3mm x 3mm mlf ? pb-free mic2230-ssyml 3.3v 3.3v C40 c to +125 c 12-pin 3mm x 3mm mlf ? pb-free note: other voltages available. contac t micrel marketing for details. pin configuration adjustable mic2230-aayml 12-pin mlf ? (ml) (top view) fixed mic2230-xxyml 12-pin mlf ? (ml) (top view) downloaded from: http:///
micrel, inc. mic2230 april 2010 3 m9999-040810-c pin description pin number adjustable pin number fixed pin name pin name 1 C fb2 feedback 2: for adjustable voltage options connect the external resistor divider network to fb2 to set the output voltage of regulator 2. nominal value is 0.8v. 2 2 en2 enable 2 input. logic low powers down regulator 2. logic high powers up regulator 2. mic2230 features built-in soft- start circuitry that reduces in-rush current and prevents the output voltage from over shooting at start up. 3 3 avin analog supply voltage: supply voltage for the analog control circuitry. requires bypass capacitor to gnd. 4 4 sw2 switch node for regulator 2, connected to external inductor. 5 5 agnd analog (signal) ground. 6 6 pgnd power ground. 7 7 /fpwm forced pwm mode bar. grounding this pin forces the device to stay in constant frequency pwm mode only. pulling this pin high enables automatic trickle mode tm operation. 8 8 sw1 switch node for regulator 1, connected to external inductor. 9 9 vin supply voltage: supply voltage for the internal switches and drivers. 10 10 pgood power good output. this output is pulled down unless the regulator 1 output voltage is within +6.25% and -8.5% of regulation. after the output volt age is in regulation, the output starts to go high with an internal 5a current source. a delay time could be programmed by tying a capacitor to this pin. 11 11 en1 enable 1 input. logic low powers down regulator 1. logic high powers up regulator 1. mic2230 features built-in soft- start circuitry that reduces in-rush current and prevents the output voltage from over shooting at start up. 12 C fb1 feedback 1: for adjustable volt age options connect to the external resistor divider network to fb1 to set the output voltage of regulator 1. nominal value is 0.8v. C 1 out2 output voltage 2. for fixed output voltage options connect out2 to the output volt age of regulator 2. C 12 out1 output voltage 1. for fixed output voltage options connect out1 to the output volt age of regulator 1. ep ep ep back-side pad. downloaded from: http:///
micrel, inc. mic2230 april 2010 4 m9999-040810-c absolute maximum ratings (1) supply voltage (v in ) .......................................................+6v enable 1 voltage ... +6v enable 2 voltage .. +6v logic input voltage (v en , v fpwm )............................ 0v to v in storage temperature (t s ) ........................C65 c to +150 c esd .............................................................................. 2kv operating ratings (2) supply voltage (v in ) ........................................ 2.5v to 5.5v junction temperature (t j ) ........................ C40 c to +125 c package thermal resistance ( ja ) ..........................60 c/w electrical characteristics (4) t a = 25c with v in = v en1 = v en2 =3.6v, v out1 , v out2 , l= 2.2h, c = 10f, unless otherwise specified. bold values indicate C40oc t j +125oc. parameter condition min typ max units supply voltage and current supply voltage range 2.5 5.5 v uvlo (rising) 2.3 2.4 2.5 v uvlo hysteresis 100 mv pwm mode supply current /fpwm = low; v out1 , v out2 = 1.03 * v nom (not switching) 560 950 a trickle mode tm supply current /fpwm = high; v out1 , v out2 = 1.03 * v nom (not switching) 28 50 a shutdown quiescent current v en = 0v 0.1 1 a output voltage accuracy feedback voltage, v fb adjustable 0.780 0.8 0.820 v output voltage, v out fixed output options -2.5 +2.5 % feedback bias current 10 na output voltage line regulation 2.5v v in 5.5v 0.1 0.5 % output voltage load regulation v in = 5v, i out = 10ma to 800ma, /fpwm = 0v v in = 3v; i out = 10ma to 800ma, /fpwm = 0v 0.5 % ripple in trickle mode tm v in =3.6v; i out = 1ma; c out = 10f, l = 2.2h. 40 mv logic inputs on 0.8 1.2 v en input threshold off 0.3 0.7 v en input current 0.01 1 a on 0.6v in v /fpwm input threshold off 0.3v in v /fpwm input current 0.01 1 a downloaded from: http:///
micrel, inc. mic2230 april 2010 5 m9999-040810-c electrical characteristics (cont.) (4) parameter condition min typ max units protection current limit peak switch current, v out = 0v 0.9 1.2 1.8 a control maximum duty cycle v fb = 0.7v 100 % oscillator pwm mode frequency 2.125 2.5 2.875 mhz power good power good reset threshold upper threshold lower threshold -14 6.25 -8.5 12 % pgood series resistance 1 1.4 k ? pgood pull-up current output within 8.5% of regulation 5 a power switch switch on-resistance i sw = 150ma (pfet) i sw = 150ma (nfet) 0.4 0.35 notes: 1. exceeding the absolute maximum rating may damage the device. 2. the device is not guaranteed to function outside its operating rating. 3. devices are esd sensitive. handling precautions recommended. human body model, 1.5k ? in series with 100pf. 4. specification for packaged product only. downloaded from: http:///
micrel, inc. mic2230 april 2010 6 m9999-040810-c typical characteristics downloaded from: http:///
micrel, inc. mic2230 april 2010 7 m9999-040810-c typical characteristics (continued) downloaded from: http:///
micrel, inc. mic2230 april 2010 8 m9999-040810-c functional characteristics vin = 3.6v, vout = 1.8v, l = 2.2h, /fpwm = 0 vi n = 3.6v, vout = 1.8v, l = 2.2h, /fpwm = 3.6v downloaded from: http:///
micrel, inc. mic2230 april 2010 9 m9999-040810-c functional characteristics (continued) downloaded from: http:///
micrel, inc. mic2230 april 2010 10 m9999-040810-c functional block diagram functional description vin vin provides power to the mosfets for the switch mode regulator section, along with the current limiting sensing. due to the high switching speeds, a 10f capacitor is recommended close to vin and the power ground (pgnd) pin for bypassing. please refer to layout recommendations. avin analog v in (avin) provides power to the analog supply circuitry. avin and vin must be tied together. careful layout should be considered to ensure high frequency switching noise caused by vin is reduced before reaching avin. a 1f capacitor as close to avin as possible is recommended. s ee layout recommendations for detail. en1 enable 1 controls the on and off state of regulator 1. a high logic on enable 1 (en1) activates regulator 1 while a low logic deactivates regul ator 1. mic2230 features built-in soft-start circuitry t hat reduces in-rush current and prevents the output volt age from overshooting at start up. en2 enable 2 controls the on and off state of regulator 2. a high logic on enable 2 (en2) activates regulator 2 while a low logic deactivates regul ator 2. mic2230 features built-in soft-start circuitry t hat reduces in-rush current and prevents the output volt age from overshooting at start up. /fpwm the forced pwm mode selects the mode of operation for this device. grounding this pin forces the device to stay in constant frequency pwm mode only. pulling this pin high enables automatic selection of trickle or pwm mode operation, depending on the load. while /fpwm is high and the load is below 100ma, the device will go into trickle mode?. if the load is above 100ma, pwm mode will automatically be selected. do not leave this pin floating. pgood the power good output is pulled down unless the regulator 1 output voltage is within +6.25% or -8.5% of regulation. when the output voltage is in regulation, the pgood capacitor will be charged to avin by an internal 5 a current source through a 1k ? resistor. the charge downloaded from: http:///
micrel, inc. mic2230 april 2010 11 m9999-040810-c time is approximately 1s per 1pf of capacitance. for example, a 390pf capacitor at the pgood pin will cause the pgood pin voltage to rise from low to high in around 390s. a pgood capacitor is recommended to prevent large output voltage transients from triggering the pgood flag unexpectedly. figure 1. power good circuit fb1/fb2 the feedback pin (fb) provides the control path to control the output. for adjustable versions, a resistor divider connecting the feedback to the output is used to adjust the desired output voltage. the output voltage is calculated as follows: v out = v ref r1 r2 + 1 ? ? ? ? ? ? where v ref is equal to 0.8v. a feedforward capacitor is recommended for most designs using the adjustable output voltage option. to reduce battery current draw, a 100k ? feedback resistor is recommended for use from the output to the fb pin (r1). also, a feedforward capacitor should be connected between the output and feedback (across r1). the large resistor value and the parasitic capacitance of the fb pin can cause a high frequency pole that can reduce the overall system phase margin. by placing a feedforward capacitor, these effects can be significantly reduced. refer to the feedback section for recommended feedforward capacitor values. sw1/sw2 the switch (sw) pin connects directly to the inductor and provides the switching current necessary to operate in pwm mode. due to the high speed switching on this pin, the switch node should be routed away from sensitive nodes. pgnd power ground (pgnd) is the ground path for the high current pwm mode. the current loop for the power ground should be as small as possible and separate from the analog ground (agnd) loop. refer to the layout considerations for more details. agnd signal ground (agnd) is the ground path 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 lay out considerations for more details. downloaded from: http:///
micrel, inc. mic2230 april 2010 12 m9999-040810-c applications information input capacitor a minimum 2.2f ceramic is recommended on the vin pin for bypassing. x5r or x7r dielectrics are recommended for the input capacitor. y5v dielectrics, aside from losing most of their capacitance over temperature, they also be come resistive at high frequencies. this reduces their ability to filter out high frequency noise. output capacitor the mic2230 was designed specifically for use with a 10f or greater ceramic output capacitor. the output capacitor requires either an x7r or x5r dielectric. y5v and z5u dielectric capacitors, aside from the undesirable effect of their wide variation in capacitance over temperature, become resistive at high frequencies. inductor selection inductor selection will be determined by the following (not necessarily in the order of importance); ? inductance ? rated current value ? size requirements ? dc resistance (dcr) the mic2230 was designed for use with a 2.2h inductor. maximum current ratings of the inductor are generally given in two methods; permissible dc current and saturation current. permissible dc current can be rated either for a 40c temperature rise or a 10 to 20% loss in inductance. ensure the inductor selected can handle the maximum operating current. when saturation current is specified, make sure that there is enough margin that the peak current will not saturate the inductor. the size requirements refer to the area and height requirements that are necessary to fit a particular design. please refer to the inductor dimensions on their datasheet. dc resistance is also important. while dcr is inversely proportional to size, dcr can represent a significant efficiency loss. refer to the efficiency considerations. compensation the mic2230 is an internally compensated, current mode buck regulator. current mode is achieved by sampling the peak current and using the output of the error amplifier to pulse width modulate the switch node and maintain output voltage regulation. the mic2230 is designed to be stable with a 2.2h inductor with a 10f ceramic (x5r) output capacitor. feedback the mic2230 provides a feedback pin to adjust the output voltage to the desired level. this pin connects internally to an error amplifier. the error amplifier then compares the voltage at the feedback to the internal 0.8v reference voltage and adjusts the output voltage to maintain regulation. calculating the resistor divider network for the desired output is as follows; ? ?? ? ? ?? ? ? = 1 v v r1 r2 ref out where v ref is 0.8v and v out is the desired output voltage. a 100k ? from the output to the feedback is recommended for r1. larger resistor values require an additional capacitor (feed-forward) from the output to the feedback. the large high-side resistor value and the parasitic capacitance on the feedback pin (~10pf) can cause an additional pole in the control loop. the additional pole can create a phase loss at high frequencies. this phase loss degrades transient response by reducing phase margin. adding feed- forward capacitance negates the parasitic capacitive effects of the feedback pin. refer to table 1 for recommended feedforward capacitor values. recommended c ff total feedback resistance 22pf 1m - 2m ? 47pf 500k -1m ? 100pf 100k - 500k ? 180pf 10k - 100k ? table 1. recommended feed-forward capacitor large feedback resistor va lues increase impedance, making the feedback node more susceptible to noise pick-up. a feed forward capacitor would also reduce noise pick-up by providing a low impedance path to the output. refer to table 1 for recommended feedforward capacitor values. efficiency considerations efficiency is defined as the amount of useful output power, divided by the amount of power supplied. 100 i v i v _% efficiency in in out out ? ?? ? ? ?? ? = maintaining high efficiency serves two purposes. it reduces power dissipation in the power supply, reducing the need for heat sinks and thermal design considerations and it reduces consumption of current for battery powered applications. reduced current draw downloaded from: http:///
micrel, inc. mic2230 april 2010 13 m9999-040810-c from a battery increases the devices operating time and is critical in hand held devices. 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 2 . during the off cycle, the low side n-channel mosfet conducts, also dissipating power. device operating current also reduces efficiency. the product of the quiescent (operating) current and the supply voltage is another dc loss. the current required driving the gates on and off at a const ant 2.5mhz frequency and the switching transitions make up the switching losses. the figure above shows an efficiency curve. from no load to 100ma, efficiency losses are dominated by quiescent current losses, gate drive and transition losses. by forcing the mic2230 into trickle mode? (/fpwm=high), the buck regulat or significantly reduces the required switching current by entering into a pfm (pulse frequency modulation) mode. this significantly increases efficiency at low output currents. over 100ma, efficiency loss is dominated by mosfet rdson and inductor losses. higher input supply voltages will increase the gate-to-source threshold on the internal mosfets, reducing the internal rdson. this improves efficiency by reducing dc losses in the device. all but the inductor losses are inherent to the device. in which case, inductor selection becomes increasingly critical in efficiency calculations. as the inductors are reduced in si ze, the dc resistance (dcr) can become quite significant. the dcr losses can be calculated as follows; dcr iout l_pd 2 = from that, the loss in efficiency due to inductor resistance can be calculated as follows; 100 l_pd i v i v 1 _loss efficiency out out out out ? ?? ? ? ?? ? ? ?? ? ? ?? ? + ? = efficiency loss due to dcr is minimal at light loads and gains significance as the load is increased. inductor selection becomes a trade-off between efficiency and size in this case. trickle mode? operation trickle mode? operation is achieved by clamping the minimum peak current to approximately 150ma. this forces a pfm mode by comparing the output voltage to the internal reference. if the voltage is less than 0.8v, the mic2230 turns on the high side until the peak inductor current reaches approximately 150ma. a separate comparator then monitors the output voltage. if the feedback voltage is greater than 0.8v, the high side switch is then used as a 10a current source, never turning off completely. this creates a highly efficient light load mode by increasing the time it takes for the output capacitor to discharge, delaying the amount of switching required and increasing light load efficiency. when the load current is greater than approximately 100ma, the mic2230 automatically switches to pwm mode. fpwm operation in forced pwm mode (/fpwm=low) the mic2230 is forced to provides constant switching at 2.5mhz with synchronous internal mosfets throughout the load current. in fpwm mode, the output ripple can be as low as 7mv. downloaded from: http:///
micrel, inc. mic2230 april 2010 14 m9999-040810-c mic2230 adjustable option (1.8v, 1.8v) bill of materials item part number manufacturer description qty c1 c1608x5r0j106k tdk 10f ceramic capacitor, 6.3v, x5r, size 0603 1 c2 c1005x5r0j105k tdk 1f ceramic capacitor, 6.3v, x5r, size 0402 1 c3 c0603y391kxxa vishay 390pf ceramic capacitor, 25v, x7r, size 0603 1 c4, c7 0603zd106mat avx 10f ceramic capacitor, 6.3v, x5r, size 0603 2 c5, c6 vj0603a220kxxat vishay 22pf ceramic capacitor, 25v, npo, size 0603 2 cdrh2d11/hpnp-2r2nc sumida 2.2h, 1.1a i sat ., 120m ? , (1.2mm 3.2mm 3.2mm) lqh43cn2r2m03 murata 2.2h, 900ma i sat ., 110m ? , (2.6mm 3.2mm 4.5mm) l1, l2 epl2014-222mlb coilcraft 2.2h, 1.3a i sat ., 120m ? , (1.4mm x 1.8mm x 2.0mm) 2 r2, r4 crcw06034423ft1 vishay 442k ? , 1%, size 0603 2 r1, r3 crcw06035493ft1 vishay 549k ? , 1%, size 0603 2 u1 mic2230-aayml micrel 2.5mhz dual phase pwm buck regulator 1 1. tdk: www.tdk.com 2. murata: www.murata.com 3. sumida: www.sumida.com 4. vishay-dale: www.vishay.com 5. avx: www.avx.com 6. micrel, inc : www.micrel.com downloaded from: http:///
micrel, inc. mic2230 april 2010 15 m9999-040810-c mic2230 fixed opti on (1.8v, 1.575v) bill of materials item part number manufacturer description qty c1 c1608x5r0j106k tdk 10f ceramic capacitor, 6.3v, x5r, size 0603 1 c2 c1005x5r0j105k tdk 1f ceramic capacitor, 6.3v, x5r, size 0402 1 c3 c0603y391kxxa vishay 390pf ceramic capacitor, 25v, x7r, size 0603 1 c4, c5 0603zd106mat avx 10f ceramic capacitor, 6.3v, x5r, size 0603 2 cdrh2d11/hpnp-2r2nc sumida 2.2h, 1.1a i sat ., 120m ? , (1.2mm 3.2mm 3.2mm) lqh43cn2r2m03 murata 2.2h, 900ma i sat ., 110m ? , (2.6mm 3.2mm 4.5mm) l1, l2 epl2014-222mlb coilcraft 2.2h, 1.3a i sat ., 120m ? , (1.4mm x 1.8mm x 2.0mm) 2 u1 mic2230-gfhyml micrel 2.5mhz dual phase pwm buck regulator 1 1. tdk: www.tdk.com 2. murata: www.murata.com 3. sumida: www.sumida.com 4. vishay-dale: www.vishay.com 5. avx: www.avx.com 6. micrel, inc : www.micrel.com downloaded from: http:///
micrel, inc. mic2230 april 2010 16 m9999-040810-c layout recommendations top layer agnd layer downloaded from: http:///
micrel, inc. mic2230 april 2010 17 m9999-040810-c layout recommendations vin and avin layer pgnd layer downloaded from: http:///
micrel, inc. mic2230 april 2010 18 m9999-040810-c package information 12-pin 3mm 3mm mlf? (ml) 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 the information furnished by micrel in this data sheet is believ ed to be accurate and reliable. however, no responsibility is a ssumed by micrel for its use. micrel reserves the right to change circuitry and specific ations at any time without notification to the customer. micrel products are not designed or authorized for use as components in life suppor t appliances, devices or systems where malfu nction of a product can reasonably be expected to result in personal injury. life supp ort devices or systems are devices or systems that (a) are in tended for surgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. a purchasers use or sale of micrel produc ts for use in life support app liances, devices or systems is a purchasers own risk and purchaser agrees to fully indemnify micrel for any damages resulting from such use or sale. ? 2007 micrel, incorporated. downloaded from: http:///

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