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mic2224 high efficiency 2mhz pwm buck converter with dac input and 40m ? bypass switch mlf and micro leadframe are registered trademarks or amkor technology, inc. micrel inc. ? 2180 fortune drive ? san jose, ca 95131 ? usa ? te l +1 (408) 944-0800 ? fax + 1 (408) 474-1000 ? http://www.micre l.com september 2006 1 m9999-091106 general description the mic2224 is a high efficiency 2mhz pwm synchronous buck switching regulator opti mized for powering 2.5g and 3g cdma rf power amplifiers. the output voltage of mic2224 can be dynamically adjusted with an external dac to maximize pa efficiency versus required output power. when the pa requires the highest power, the dac can be used to enable a low on-resistance, 40m ? , bypass switch that powers the pa directly from the battery. the 2mhz pwm operation of mic2224 allows the smallest possible components. it also allows the device to easily meet stringent w-cdma v out response specifications. the mic2224 operates from a 2.7v to 5.5v input, making it ideal for single cell li-ion applications. the device features built-in power mosfets that can supply up to 600ma of output current in pwm mode, or over 1a in bypass mode. the mic2224 can operate with a maximum duty cycle of 100% for use in low-dropout conditions. the mic2224 has a junction temperature range of ?40c to +125c and is available in a 10-pin 3mm x 3mm mlf ? package. data sheets and support doc umentation can be found on micrel?s web site at www.micrel.com. features ? 2.7v to 5.5v input voltage range ? dac-adjustable output voltage down to 0.3v ? 600ma output current in pwm mode ? internally protected 40m ? bypass switch ? allows direct connection of battery to load ? over 95% efficient ? fully integrated mosfet switches ? constant 2mhz pwm operation ? internal soft-start ? 1% line and load regulation ? <1a shutdown current ? under-voltage lockout ? thermal shutdown and current limit protection ? ?40c to +125c junction temperature range applications ? cellular phones ? pdas typical application mic2224 vin avin enable dac dac v in 2.6v to 5.5v gnd gnd v out c1 1f c2 1f l1 4.7h agnd pgnd vout sw 2, 3 5 4 6 710 8, 9 1 2mhz pwm converter with dac input and 40m ? bypass switch 0 0.6 1.2 1.8 2.4 3.0 3.6 4.2 4.8 5.4 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 v out (v) v dac (v) v in =4.2v v ou t = v d a c x3 bypass mode
micrel, inc. mic2224 september 2006 2 m9999-091106 ordering information (1) part number output voltage junction temp. range package lead finish MIC2224YML adj. ?40c to +125c 10-pin 3mm x 3mm mlf ? pb-free pin configuration sw vin vin en pgnd vout vout agnd 1 2 3 4 10 9 8 7 56 avin dac ep 10-pin mlf ? (ml) pin description pin number pin name pin function 1 sw switch (output): internal power mosfet output switches. 2, 3 vin supply voltage (input): requires bypass capacitor to gnd. 4 en a low level en will power down the devic e, reducing the quiescent current to under 5a (typ 1a). 5 avin supply voltage (input): requires bypass capacitor to gnd. 6 dac dac control input. provides control of outpu t voltage. the output voltage is 3 x the dac voltage. (ex. 0.5vdac = 1.5v out ). bypass mode is enabled when the dac voltage exceeds 1.2v. 7 agnd signal ground of chip. 8, 9 vout source of internal p-channel mosfet and feedback of internal pwm regulator. 10 pgnd power ground of chip. ep exposed pad connect to ground.
micrel, inc. mic2224 september 2006 3 m9999-091106 absolute maximum ratings (1) supply voltage (v in ) ............................................... 0v to 6v output switch voltage (v sw ). ...........................................6v dac input voltage (v dac )............................ 0v to v in +0.3v output switch current (i sw )...........................................2.5a logic input voltage (v en ) ............................ 0v to v in +0.3v storage temperature (t s ) .........................?65c to +150c operating ratings (2) supply voltage (v in ) ....................................... 2.7v to +5.5v output voltage (v out ). ........................................ 0v to 5.5v dac input voltage (v dac ).................................... 0.1v to v in junction temperature (t j ) ........................ ?40c to +125c thermal resistance mlf ? -10 ( ja ) ....................................................60c/w electrical characteristics (4) v in = v en = 3.6v; v dac = 0.6v; l = 4.7h; c out = 1f; t a = 25c, bold values indicate ?40c< t j < +125c, unless noted. parameter condition min typ max units supply voltage range 2.7 5.5 v total quiescent current vdac = 0.6v vout = 2.4v (regulator on, not switching) 360 450 a shutdown current ven = 0v (regulator off) 1 5 a maximum duty cycle 100 % regulation output voltage vdac = 0.6v, iload =0ma 1.746 1.8 1.854 v output voltage line regulation 3.0v vin 4.5, iload= 10ma 0.05 0.5 %/v output voltage load regulation 0ma < iout < 500ma 0.2 % output switch on-resistance isw = -100ma, high-side switch isw = 100ma , low-side switch 0.55 0.6 0.75 0.85 ? ? current limit (peak sw current) 0.65 0.85 1.6 a oscillator frequency 1.8 2 2.2 mhz enable / uvlo enable pin threshold 0.5 0.9 1.3 v enable pin hysteresis 30 mv enable pin input current 0.01 1 a en high to 90% vout 25 50 s under-voltage lockout threshold (turn-on) 2.6 2.7 v uvlo hysteresis 85 mv dac input dac input current 0.15 2 a output voltage/dac voltage (internally set) 3 v/v bypass switch bypass switch threshold 1.176 1.2 1.224 v bypass switch hysteresis 35 mv bypass transition time 10 s bypass switch on-resistance 40 m ? bypass switch leakage 5 a bypass over-current limit 1 1.4 2.5 a current limit retry time 32 s current limit retry duty cycle 12.5 %
micrel, inc. mic2224 september 2006 4 m9999-091106 parameter condition min typ max units over temperature shutdown shutdown temperature 160 c over temperature shutdown hysteresis 20 c 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 re commended. human body model, 1.5k in series with 100pf. 4. specification for packaged product only.
micrel, inc. mic2224 september 2006 5 m9999-091106 typical characteristics 70 75 80 85 90 95 100 0 0.1 0.2 0.3 0.4 0.5 0.6 efficiency (%) output current (a) efficiency 2.7v out 3v in 3.6v in 4.2v in 60 65 70 75 80 85 90 95 100 0 0.1 0.2 0.3 0.4 0.5 0.6 efficiency (%) output current (a) efficiency 1.8v out 3v in 3.5v in 4v in 50 55 60 65 70 75 80 85 90 95 100 0 0.1 0.2 0.3 0.4 0.5 0.6 efficiency (%) output current (a) 3v in 3.6v in 4.2v in efficiency 1.5v out 50 55 60 65 70 75 80 85 90 95 100 0 0.1 0.2 0.3 0.4 0.5 0.6 efficiency (%) output current (a) 3v in 3.6v in 4.2v in efficiency 1.2v out 0 10 20 30 40 50 60 70 80 90 100 0 0.1 0.2 0.3 0.4 0.5 0.6 efficiency (%) output current (a) 3v in 3.6v in 4.2v in efficiency 0.9v out 40 50 60 70 80 90 100 0 0.1 0.2 0.3 0.4 0.5 0.6 efficiency (%) output current (a) 3v in 3.6v in 4.2v in efficiency 0.6v out 1.773 1.782 1.791 1.800 1.809 1.818 1.827 0 100 200 300 400 500 600 output voltage (v) load current (ma) load regulation v out =1.8v v dac =0.6v v in =3.6v 1.746 1.755 1.764 1.773 1.782 1.791 1.800 1.809 1.818 1.827 1.836 -40 -20 0 20 40 60 80 100 120 output voltage (v) temperature (c) output voltage vs. temperature v dac =0.6v 2.7 2.8 2.9 3.0 3.1 3.2 3.3 -40 -20 0 20 40 60 80 100 120 v out /dac temperature (c) v out /dac vs. temperature 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 v out /dac dac voltage (v) output voltage vs. dac voltage 25c -40c 125c 1.80 1.85 1.90 1.95 2.00 2.05 2.10 2.15 2.20 -40 -20 0 20 40 60 80 100 120 frequency (mhz) temperature (c) frequency vs. temperature 0 50 100 150 200 250 300 350 400 450 -40 -20 0 20 40 60 80 100 120 quiescent current (a) temperature (c) quiescent current vs. temperature v in =3.6v
micrel, inc. mic2224 september 2006 6 m9999-091106 typical characteristics (cont.) 0 50 100 150 200 250 300 350 400 450 2.7 3.26 3.82 4.38 4.94 5.5 quiescent current (a) supply voltage (v) quiescent current vs. temperature 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 2.7 3.26 3.82 4.38 4.94 5.5 enable threshold (v) supply voltage (v) enable threshold vs. supply voltage
micrel, inc. mic2224 september 2006 7 m9999-091106 functional characteristics bypass mode transient time 10s dac voltage (500mv/div) output voltage (2v/div) v in = 4.2v l = 4.7h c out = 1f 0v 0v bypass mode transient time 10s dac voltage (500mv/div) output voltage (2v/div) v in = 4.2v l = 4.7h c out = 1f 0v 0v current limit transient (bypass mode) time 2ms output current (500ma/div) output voltage (2v/div) v in = 3.6v vdac = 1.3v l = 4.7h c out = 1f 0ma 0v current limit transient (pwm mode) time 100s output current (500ma/div) output voltage (2v/div) v in = 3.6v vdac = 1.3v l = 4.7h c out = 1f 0ma 0v enable transient time 10s enable voltage (1v/div) output voltage (1v/div) v in = 3.6v vdac = 0.6v l = 4.7h c out = 1f 0v 0v load transient time 10s output current (100ma/div) output voltage (100mv/div) v in = 3.6v vdac = 0.6v l = 4.7h c out = 1f 0ma
micrel, inc. mic2224 september 2006 8 m9999-091106 functional characteristics (cont.) output voltage transient time 10s dac voltage (500mv/div) output voltage (1v/div) v in = 3.6v l = 4.7h c out = 1f 0v 0v output voltage transient time 10s dac voltage (500mv/div) output voltage (1v/div) v in = 3.6v l = 4.7h c out = 1f 0v 0v switch voltage - output ripple time 400ns switch voltage (2v/div) output voltage ripple ac coupled (10mv/div) v in = 3.6v vdac = 0.6v i out = 600ma l = 4.7h c out = 1f
micrel, inc. mic2224 september 2006 9 m9999-091106 functional diagram 1.2v driver avin vin dac en 80k 40k agnd pgnd sw vout mic2224 block diagram
micrel, inc. mic2224 september 2006 10 m9999-091106 functional description vin vin provides power to the mosfets for the switch mode regulator section, al ong with the current limiting sensing. due to the high switching speeds, a 1f capacitor is recommended close to vin and the power ground (pgnd) pin for bypassing. avin analog vin (avin) provides power to the internal reference and control section. avin and vin must be tied together. careful layout should be considered to ensure high frequency switchi ng noise caused by vin is reduced before reaching avin. dac the dac pin is the control pin that sets the output voltage. the output voltage is 3x the voltage set on the dac pin. when 1.2v or great er is applied to the dac pin, the mic2224 enters by pass mode. in bypass mode, the input supply is connected to the output through a 40m ? p-channel mosfet. en the enable pin provides a l ogic level control of the output. in the off state, suppl y current of the device is greatly reduced (typically <1a ). also, in the off state, the output drive and bypass switch are placed in a "tri- stated" condition, where both the high side p-channel mosfet and the low-side n-ch annel are in an off or non- conducting state. do not driv e the enable pin above the supply voltage. vout the vout pin connects the internal bypass drain and the feedback signal to the output. the bypass applies the input voltage through a low resistance (40m ? typical) p-channel mosfet switch. the feedback signal provides the control path to set the output at 3x the dac voltage. sw 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. 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.
micrel, inc. mic2224 september 2006 11 m9999-091106 application information the mic2224 is a 600ma pwm power supply that utilizes a dynamically adjust able output voltage for powering rf power amplifiers . by dynamically adjusting the output power as necess ary, battery life can be dramatically improved in battery powered rf applications. for instances where high power is required, the mic2224 also has a bypass mode. bypass mode is enabled by driving the dac pin above 1.2v. this bypasses the input supply directly to the output through a highly efficient, short circuit protected, 40m ? p channel mosfet. input capacitor a minimum 1f ceramic is recommended on the vin pin for bypassing. x5r or x7r dielectrics are recommended for the input capacitor. y5v di electrics lose most of their capacitance over temperature and are therefore not recommended. a minimum 1f is recommended close to the vin and pgnd pins for high frequency filtering. smaller case size capacitors are recommended due to their lower esr and esl. output capacitor the mic2224 is optimized for a 1f ceramic output capacitor. the mic2224 utilizes type iii internal compensation and utilizes in ternal high frequency zeros to compensate for the double pole roll off of the lc filter. for this reason, larger out put capacitors can create instabilities. x5r or x7r di electrics are recommended for the output capacitor. y5v dielectrics lose most of their capacitance over temper ature and are therefore not recommended. in addition to a 1f, a small 10nf is recommended close to the load for high frequency filtering. smaller case size capacitors are recommended due to there lower esr and esl. inductor selection the mic2224 is designed for use with a 4.7h inductor. proper selection should ensure the inductor can handle the maximum average and pea k currents required by the load. maximum current rati ngs 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. peak inductor current can be calculated as follows: l f 2 v v 1 v i i in out out out pk ? ? ? ? ? ? ? ? ? + =
micrel, inc. mic2224 september 2006 12 m9999-091106 bill of materials mic2224 vin avin enable dac dac v in 2.7v to 5.5v gnd gnd v out c1 1f c2 1f l1 4.7h agnd pgnd vout sw 2, 3 5 4 6 710 8, 9 1 item part number manufacturer description qty. 06036d105mat2 avx (1) c1608x5r0j105k tdk (2) c1, c2 grm185r60j105ke21d murata (3) 1f ceramic capacitor x5r, 6.3v 0603 2 lqh32cn4r7m53k murata (3) 4.7h 3.2mm x 2.5mm x 1.55mm cdrh2d14-4r7 sumida (4) 4.7h inductor 94m ? 3.2mm x 3.2mm x 1.55mm l1 glf201208t4r7m* tdk (2) 4.7h inductor 660m ? 1 u1 MIC2224YML micrel (5) micrel data sheet title here 1 notes : 1. avx tel: 843-448-9411 2. tdk. tel: 714-508-8800 3. murata tel: 949-916-4000 4. sumida tel: 408-982-9660 5. micrel semiconductor tel: 408-944-0800 * for maximum load currents less than 200ma
micrel, inc. mic2224 september 2006 13 m9999-091106 package information 10-pin 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 belie ved to be accurate and reliable. however, no responsibility is a ssumed by micrel for its use. micrel reserves the right to change circuitry and specifications at any time without notification to the customer. micrel products are not designed or authori zed for use as components in life support app liances, devices or systems where malfu nction of a product can reasonably be expected to result in personal injury. life suppo rt 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 significan t injury to the user. a purchaser?s use or sale of micrel produc ts for use in life support app liances, devices or systems is a purchaser?s own risk and purchaser agrees to fully indemnify micrel for any damages resulting from such use or sale. ? 2005 micrel, incorporated.

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