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mic23158/9 3mhz pwm dual 2a buck regulator w ith h yperlight load ? and power good hyperlight load is a registered trademark of micrel, inc. mlf and micro leadframe a re registered trademark s 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 november 2012 m9999 -1 10812 -a general description the mic23158/9 is a high - efficiency , 3mhz , dual , 2a synchronous buck regulator with hyperlight load ? mode , power good output indicator, and programmable s oft s tart . the mic23159 also provides an auto discharge feature that switches in a 225 ? pull down circuit on its output to discharge the output capacitor when disabled. hyperlight load provides very high efficiency at light loads and ultra - fast transient response which makes the mic23158/9 perfectly suited for supplying processor core volt a ges. an additional benefit of this proprietary architecture is very low output ripple voltage throughout the entire load range with the use of small output capacitors. the 20 - pin 3 mm x 4 mm mlf ? package saves precious board space and requires seven external components for each channel . the mic23158/9 is designed for use with a very small inductor, down to 0.47h, and an output capacitor as small as 2.2f that enables a total solution size, less than 1mm in height. the mic23158/9 has a very low quiescent curr ent of 45 a and achiev es a peak efficiency of 94 % in continuous conduction mode. in discontinuous conduction mode, the mic23158/9 can achieve 83 % efficiency at 1ma. the mic23158/9 is available in a 20 - pin 3 mm x 4 mm mlf package with an operating junction temperature range from C 40 c to +125 c. datasheets and support documentation can be found on micrels web site at: www.micrel.com . features ? 2.7v to 5.5v input voltage ? adjustable output vo ltage ( down to 1.0v ) ? 2 inde pendent 2a outputs ? up to 94 % peak efficiency ? 83 % typical efficiency at 1ma ? 2 independent power good indicators ? independent p rogrammable soft start ? 45 a typical quiescent current ? 3mhz pwm operation in continuous conduction mode ? ultra - fast transient response ? fu lly - integrated mosfet switches ? output p re - bias safe ? 0.1 a shutdown current ? thermal - shutdown and current - limit protection ? 20 - pin 3 mm x 4 mm mlf package ? internal 225 ? pull - down circuit on output (mic23159) ? C 40 c to +125 c junction temperature range applications ? solid state drives (ssd) ? smart phones ? tablet pcs ? mobile handsets ? portable devices (pmp, pnd, umpc, gps ) ? wifi/wimax/wibro applications _________________________ _ _____________________________________________ __ ______________________________ typical application downloaded from: http:///
micrel inc. mic2315 8/9 november 2012 2 m9999 -1 10812 -a ordering information part number nominal output voltage output auto discharge junction temperature range package v out 1 v out 2 mic23158yml adj adj no C 40 c to +125 c 20 - pin 3mm x 4mm mlf mic23159yml adj adj yes C 40 c to +125 c 20 - pin 3mm x 4mm mlf notes: 1. f ixed output voltage options available . contact micrel marketing for details. 2. mlf is a green rohs - compliant package. lead finish is nipdau. mold compound is halogen free. pin configuration 1 1 2 3 4 5 6 16 15 14 13 12 11 7 8 10 9 20 19 17 18 ep vin1 sw2 sw1 pgnd1 pgnd2 vin2 avin2 agnd2 en2 sns2 fb2 pg2 ss2 ss1 pg1 fb1 avin1 agnd1 en1 sns1 3 mm x 4 mm mlf (ml) adjustable output voltage (top view) pin description pin number (adjustable) pin name pin function 1 vin1 power input voltage for r egulator 1. connect a ca pacitor to ground to decouple noise and switching transients. 2 pgnd1 power ground for r egulator 1. 3 sw1 switch (output): internal power mosfet output switches for regulator 1. 4 sw2 switch (output): internal power mosfet output switches for regulator 2. 5 pgnd2 power ground for r egulator 2. 6 vin2 power input voltage for r egulator 2. connect a capacitor to ground to decouple noise and switching transients. 7 avin2 analog input voltage for r egulator 2. tie to vin2 and connect a capacitor to ground to decouple noise. downloaded from: http:///
micrel inc. mic2315 8/9 november 2012 3 m9999 -1 10812 -a pin description (continued) pin number (adjustable) pin name pin function 8 agnd2 analog ground for r egulator 2. connect to a central ground point where all high current paths meet (c in , c out , pgnd2) for best operation. 9 en2 enable in put for r egulator 2. logic high enables operation of regulator 2. logic low will shut down regulator 2. do not leave floating. 10 sns2 sense input for r egulator 2. connect to the output of regulator 2 as close to the output capacitor as possible to accurately sense the output voltage. 11 fb2 feedback input for r egulator 2. connect a resistor divider from the output of regulator 2 to ground to set the output voltage. 12 pg2 power good o utput for r egulator 2. open drain output for the power good indicator for output 2. use a pull - up resistor between this pin and v out2 to indicate a power good condition. 13 ss2 soft-start for r egulator 2. connect a minimum of 2 00pf capacitor to ground to set the turn - on time of regulator 2. do not leave floating. 14 ss1 so ft -start for r egulator 1. connect a minimum of 2 00pf capacitor to ground to set the turn - on time of regulator 1. do not leave floating. 15 pg1 power good o utput for r egulator 1. open drain output for the power good indicator for output 1. use a pull - up re sistor between this pin and v out1 to indicate a power good condition. 16 fb1 feedback input for r egulator 1. connect a resistor divider from the output of regulator 1 to ground to set the output voltage. 17 sns1 sense input for r egulator 1. connect to th e output of regulator 1 as close to the output capacitor as possible to accurately sense the output voltage. 18 en1 enable input for r egulator 1. logic high enables operation of regulator 1. logic low will shut down regulator 1. do not leave floating. 19 agnd1 analog ground for r egulator 1. connect to a central ground point where all high current paths meet (c in , c out , pgnd1 ) for best operation. 20 avin1 analog input voltage for r egulator 1. tie to vin1 and connect a capacitor to ground to decouple noise . ep ep ad exposed heat sink pad. connect to pgnd. downloaded from: http:///
micrel inc. mic2315 8/9 november 2012 4 m9999 -1 10812 -a absolute maximum ratings (1) supply voltage ( av in1 , av in2, v in 1 , v in 2) .... ? 0.3v to 6v switch 1 (v sw1 ), sense 1 (v sns1 ) ...................... ? 0.3v to v in 1 enable 1 (v en 1 ) , power good 1 (v pg1 ) ............. ? 0.3v to v in1 feedback1 (v fb1 ) ......................................... ? - 0.3v to vin1 switch2 (v sw2 ), sense 2 (v sns2 ) ...................... - 0.3v to vin2 enable 2 (v en 2 ) , power good 2 (v pg2 ) ............. ? 0.3v to vin2 feedback 2 (v fb2 ) ........................................... ? 0.3v to vin2 power dissipation t a = 70 c .................... internally limited storage temperature range .................... ? 65 c to +150 c lead t emperature (soldering, 10s ) ............................ 26 0 c esd rating (3) .................................................. esd sensitive operating ratings (2) supply voltage ( av in1 , v in1 ) ..................... +2.7v to +5.5v supply voltage (av in 2, v in 2) ..................... +2.7v to +5.5v enable input voltage (v en1 , v en2 ) ...................... 0v to v in 1,2 output voltage range (v sns1 , v sns2 ) .......... +1.0 v to +3.3v junction temperature range (t j ) ...... ? 40 c t j +125 c thermal resistance 3 mm x 4 mm mlf -20 ( ja ) ................................ . 53 c/w electrical characteristics (4) t a = 25c; av in1,2 = v in1,2 = v en 1,2 = 3.6v; l 1,2 = 1.0 h; c out 1,2 = 4.7f unless otherwise specified. bold values indicate C 40c t j +125c, unless noted. parameter condition min . typ . max . units supply voltage range 2.7 5.5 v underv oltage lockout threshold rising 2.45 2.55 2.65 v undervolt age lockout hysteresis 75 mv quiescent current i out = 0ma , sns > 1.2 * v outnom (bo th outputs) 45 90 a shutdown current v en = 0v; v in = 5.5v (per output) 0. 1 5 a feedback regulation voltage i out = 20ma 0.6045 0.62 0.635 5 v feedback bias current (p er output ) 0.01 a current limit sns = 0.9*v outnom 2.2 4 .3 a output voltage line regulation v in = 3. 6v to 5.5v if v outnom < 2.5v , i out = 20ma 0. 45 %/v v in = 4.5v to 5.5v if v outnom 2.5 v, i out = 20ma output voltage load regulation dcm, v in = 3.6v if v outnom < 2.5v 0.55 % dcm, v in = 5.0v if v outnom 2.5v 1.0 ccm, v in = 3.6v if v outnom < 2.5v 0.8 ccm, v in = 5.0v if v outnom 2.5v pwm switch r dson i sw 1,2 = 10 0ma pmos i sw 1,2 = - 100ma nmos 0.20 0. 19 ? switching frequency i out = 1 8 0ma 3 mhz soft- start time v out = 90% , c ss = 470pf 300 s soft- start current v ss = 0v 2.7 a power good threshold ( rising ) 86 92 96 % power good threshold hysteresis 7 % power good delay time rising 68 s power good pull -d own resistance 95 ? 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. han dling precautions recommended. human body model, 1.5k in series with 100pf. 4. specification for packaged product only. downloaded from: http:///
micrel inc. mic2315 8/9 november 2012 5 m9999 -1 10812 -a electrical characteristics (4) (continued) t a = 25c; av in1,2 = v in1,2 = v en1,2 = 3.6v; l 1,2 = 1.0 h; c out1,2 = 4.7f unless otherwise spe cified. bold values indicate C 40c t j +125c, unless noted. parameter condition min. typ. max. units enable input voltage logic low 0. 4 v logic high 1.2 enable input current 0.1 2 a output discharge resistance mic23159 only; en = 0v , i out = 250 a 225 ? over temperature shutdown 160 c shutdown hysteresis 20 c downloaded from: http:///
micrel inc. mic2315 8/9 november 2012 6 m9999 -1 10812 -a typical characteristics efficiency (v out = 3.3v) vs. output current 0 10 20 30 40 50 60 70 80 90 100 1 10 100 1000 10000 output current (ma) efficiency (%) vin = 4.2v vin = 5v c out =4.7f l=1h efficiency (v out = 2.5v) vs. output current 0 10 20 30 40 50 60 70 80 90 100 1 10 100 1000 10000 output current (ma) efficiency (%) vin = 4.2v vin = 3.6v vin = 5v c out =4.7f l=1h efficiency (v out = 1.8v) vs. output current 0 10 20 30 40 50 60 70 80 90 100 1 10 100 1000 10000 output current (ma) efficiency (%) vin = 2.7v vin = 4.2v vin = 3.6v vin = 5v c out =4.7f l=1h efficiency (v out = 1.5v) vs. output current 0 10 20 30 40 50 60 70 80 90 100 1 10 100 1000 10000 output current (ma) efficiency (%) vin = 2.7v vin = 4.2v vin = 3.6v vin = 5v c out =4.7 f l=1 h v out rise time vs. c ss 10 100 1000 10000 100000 1000000 100 1000 10000 100000 1000000 css (pf) rise time (s) v out = 1.8v c out = 4.7 f current limit vs. input voltage 0.0 1.0 2.0 3.0 4.0 5.0 6.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 input voltage (v) current limiit (a) v out = 1.8v c out = 4.7 f quiescent current vs. input voltage 20 25 30 35 40 45 50 55 60 2.5 3.0 3.5 4.0 4.5 5.0 5.5 input voltage (v) quiescent current (a) no switching sns > v outnom * 1.2 c out = 4.7f t = 125c t = -40c t = 25c shutdown current vs. input voltage 1 10 100 1000 2.5 3.0 3.5 4.0 4.5 5.0 5.5 input voltage (v) shutdown current (na) line regulation (ccm) 1.60 1.65 1.70 1.75 1.80 1.85 1.90 1.95 2.00 2.5 3.0 3.5 4.0 4.5 5.0 5.5 input voltage (v) output voltage (v) i ou t = 1a i ou t = 300ma v ou tn om = 1.8v c ou t = 4.7f downloaded from: http:///
micrel inc. mic2315 8/9 november 2012 7 m9999 -1 10812 -a typical characteristics (continued) line regulation (hll) 1.60 1.65 1.70 1.75 1.80 1.85 1.90 1.95 2.00 2.5 3.0 3.5 4.0 4.5 5.0 5.5 input voltage (v) output voltage (v) i ou t = 20ma i ou t = 80ma i ou t = 1ma v ou tn om = 1.8v c ou t = 4.7f load regulation (ccm) 1.60 1.65 1.70 1.75 1.80 1.85 1.90 1.95 2.00 200 600 1000 1400 1800 output current (ma) output voltage (v) v in = 3.6v v ou tn om = 1.8v c ou t = 4.7f load regulation (hll) 1.60 1.65 1.70 1.75 1.80 1.85 1.90 1.95 2.00 0 20 40 60 80 100 120 output current (ma) output voltage (v) v in = 3.6v v ou tn om =1.8v c ou t = 4.7f v outmax vs. v in 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 input voltage (v) output voltage (v) i out = 400ma i out = 1.2a i out = 100ma t a = 25 c feedback voltage vs. temperature 0.59 0.60 0.61 0.62 0.63 0.64 0.65 -40 -20 0 20 40 60 80 100 120 temperature (c) feedback voltage (v) v in = 3.6v v ou t = 1.8v switching frequency vs. temperature 0 1 2 3 4 5 -40 -20 0 20 40 60 80 100 120 temperature (c) switching frequency (mhz) v in = 3.6v v ou tn om = 1.8v c ou t = 4.7f downloaded from: http:///
micrel inc. mic2315 8/9 november 2012 8 m9999 -1 10812 -a functional characteristics downloaded from: http:///
micrel inc. mic2315 8/9 november 2012 9 m9999 -1 10812 -a functional characteristics (continued) downloaded from: http:///
micrel inc. mic2315 8/9 november 2012 10 m9999 -1 10812 -a functional characteristics (continued) downloaded from: http:///
micrel inc. mic2315 8/9 november 2012 11 m9999 -1 10812 -a functional diagram figure 1 . simplified mic2315 8 functional block diagram C adjustable output voltage downloaded from: http:///
micrel inc. mic2315 8/9 november 2012 12 m9999 -1 10812 -a functional diagrams (continued) figure 2. simplified mic23159 functional block diagram C adjustable output voltage downloaded from: http:///
micrel inc. mic2315 8/9 november 2012 13 m9999 -1 10812 -a functional description vin the input supply (vin) provides power to the internal mosfets for the switch mode regulator section. the vin operating range is 2.7v to 5.5v. an input capacitor with a minimum voltage rating of 6.3v is recommended. due to the high switching speed, a minimum 2.2f bypass capacitor placed close to vin and the power ground (pgnd) pin is required. refer to the pcb layout r ecommendations for details. avin analog vin (avin) provides power to the internal control and 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 1 f capacitor as close to avin as possible is recommended. refer to the pcb layout recommendations for details. en a logic high signal on the enable pin activates the output voltage of the device. a logic low signal on the enable pin deactivates the output and reduces supply current to 0. 1a. do not leave the en pin floating. when disabled, the mic23159 switches in a 225 ? load from the sns pin to agnd, to discharge the output capacitor. sw the switch (sw) connects directly to one end of the inductor and provides the current path during switching cycles. the other end of the inductor is connected to the load, sns pin , and output capacitor. due to the high speed switching on this pin, the switch node should be routed away from sensitive nodes whenever possible. sns the sense (sns) pin is connected to the output of the device to provide feedback to the control circuitry. the sns connection should be placed close to the output capacitor. refer to the layout recommendations for more details. the sns pin also provides the output active discharge circuit path to pull down the output voltage when the device is disabled. agnd the analog 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 pcb layout recommendations for details. pgnd the power ground pin is the ground path for the high current in pwm mode. the current loop for the power ground should be as small as possible and separate from the analog ground (agnd) loop as applicable. refer to the layout recommendations for more details. pg the power good (pg) p in is an open drain output which indicates when the output voltage is within regulation. this is indicated by a logic high signal when the output voltage is above the pg threshold . connect a pull up resistor greater than 5k ? from pg to v out . ss a n external soft start circuitry set by a capacitor on the ss pin reduces inrush current and prevents the output vol t ag e from overshooting at start up. the ss pin is used to control the output voltage ramp up time and th e approximate equation for the ramp time in mil liseconds is 2 96 x 10 3 x ln(10) x c ss . for example, for a c ss = 470pf, t rise 300 s. refer to the v out rise time vs. c ss graph in the t ypical c haracteris tics section . the minimum recommended value for c ss is 2 00pf. fb the feedback (fb) pin is provided for the adjustable voltage option . t his i s the control input for setting the output voltage. a resistor divider network is connected to this pin from the output and is compared to the internal 0.62 v reference within the regulation loop . the output voltage can be calculated using equation 1 : ?? ? ?? ? + ? = r2 r1 1 v v ref out eq. 1 recommen ded feedback resistor values: v out r1 r2 1.2v 274k 294k 1.5v 316k 221k 1.8v 301k 158k 2.5v 324k 107k 3.3v 309k 71.5k downloaded from: http:///
micrel inc. mic2315 8/9 november 2012 14 m9999 -1 10812 -a application information the mic23158/9 is a high - performance d c/ dc step down regulator offering a small solution size. supporting two output s of up to 2a each in a 3 mm x 4 mm mlf package . using the hyperlight load switching scheme, the mic23158/9 is able to maintain high efficiency throughout the entire load range while providing ultra fast load transient response. the following sect ions provide additional device application information. input capacitor a 2.2f ceramic capacitor or greater should be placed clo se to the vin pin and pgnd pin for bypassing. a murata grm188r60j475ke19d , size 0603, 4.7f ceramic capacitor is recommended based upon performance, size and cost. a x5r or x7r temperature rating is recommended for the input capacitor. output capacitor the mic23158/9 is designed for use with a 2.2f or greater ceramic output capacitor. increasing the output capacitance will lower output ripple and improve load transient response but could also increase solution size or cost. a low equivalent series resistance (esr) ceramic output capacitor such as the murata grm188r60j475ke19d , size 0603, 4.7f ceramic capacitor is recommended based upon performance, size and cost. both the x7r or x5r temperature rating capacitors are recommended. inductor selection when selecting an inductor, it is important to consider th e following factors : ? inductance ? rated current value ? size requirements ? dc resistance (dcr) the mic23158/9 is designed for use with a 0.47h to 2.2h inductor. for faster transient response, a 0.47h inductor will yield the best result. for lower output ripple, a 2.2h inductor is recommended. 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 so that the peak current does not cause the inductor to saturate. peak current can be calculated in equation 2: ?? ? ?? ? ? ?? ? ? ?? ? ? + = l f 2 /v v 1 v i i in out out out peak eq. 2 as shown by the calculation above, the peak inductor current is inversely proportional to the switchi ng frequency and the inductance. the lower the switching frequency or inductance, the higher the peak current. as input voltage increases, the peak current also increases. the size of the inductor depends on the requirements of the application. refer to the t ypical a pplication c ircuit and bill of materials for details. figure 3. transition between ccm mode to hll mode dc resistance (dcr) is also important. while dcr is inverse ly proportional to size, dcr can represent a significant efficiency loss. refer to the efficiency considerations subsection. the transition between continuous conduction m ode (ccm) to hyperlight l oad mode is determined by the inductor ripple current and the load current. the diagram shows the signals for high - side switch d rive (hsd) for t on control, the inductor current , and the low - side switch drive (lsd) for t off control. in hll mode, the inductor is charged with a fixed t on pulse on the high side swit ch. after this, the low side switch is turned on and current falls at a rate v out /l. the controller remains in hll mode while the inductor falling current is detected to cross approximately - 50ma. when the lsd (or t off ) time reaches its minimum and the ind uctor falling current is no longer able to reach the threshold, the part is in ccm mode . downloaded from: http:///
micrel inc. mic2315 8/9 november 2012 15 m9999 -1 10812 -a once in ccm mode, the t off time will not vary. therefore, it is important to note that if l is large enough, the hll transition level will not be triggered . that inductor is illustrated in figure 3 : 50ma 2 135ns v l out max ? ? = eq. 3 duty cycle the typical maximum duty cycle of the mic2315 8/9 is 80%. efficiency considerations efficiency is defined as the amount of useful output power, divided by the amount of power suppl ied. 100 i v i v % efficiency in in out out ? ?? ? ? ?? ? = eq. 4 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 e qual to the high side mosfet r dson multiplied by the switch c urrent squared. 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 represents another dc loss. the current required driving the gates on and off at a constant 3mhz frequency and the switching transitions make up the switching losses. efficiency (v out = 1.8v) vs. output current 0 10 20 30 40 50 60 70 80 90 100 1 10 100 1000 10000 output current (ma) efficiency (%) vin = 2.7v vin = 4.2v vin = 3.6v vin = 5v c out =4.7f l=1h figure 4 . efficiency under load figure 4 shows an efficiency curve. from 1ma load to 2 a, efficiency losses are dominated by quiescent current losses, gate drive and transition losses. by using the hyperlight load mode, the mic23158/9 is able to maintain high efficiency at low output currents. over 1 8 0ma, efficiency loss is dominated by mosfet r dson and inductor losses. higher input supply vol tages will increase the gate - to -s ource threshold on the internal mosfets, thereby reducing the internal r dson . this improves efficiency by reducing dc losses in the device . all but the inductor losses are inherent to the device. in which case, inductor selection becomes increasingly critical in efficiency calculations. as the inductors are reduced in size, the dc resistance (dcr) can become quite significant. the dcr losses can be calculated as in equation 5: p dcr = i out 2 x dcr eq. 5 from that, the loss in efficiency due to inductor resistance can be calculated as in equation 6 : 100 p i v i v 1 loss efficiency dcr out out out out ? ?? ? ? ?? ? ? ?? ? ? ?? ? + ? = eq. 6 efficiency loss due to dcr is minimal at light loads and gains significance as the load is increased. ind uctor selection becomes a trade off between efficiency and size in this case. hyperlight load mode the mic23158/9 uses a minimum on and off time proprietary control loop (patented by micrel). when the output voltage falls below the regulation threshold, the error comparator begins a switching cycle that turns the pmos on and keeps it on for the duration of the minimum - on - time. this increases the output voltage. if the output voltage is over the regulation threshold, then the error comparator turns the pmos off for a minimum - off - time until the output drops below the threshold. the nmos acts as an ideal rectifier that conducts when the pmos is off. using a n nmos switch instead of a diode allows for lower voltage drop across the switching device when it is on. the synchronous switching combination between the pmos and the nmos allows the control loop to work in discontinuous mode for light load operations. in discontinuous mode, the mic23158/9 works in hyperlight l oad to regulate the output. as the ou tput current increases, the off time decreases, thus provides more energy to the output. this switching scheme improves the efficiency of mic23158/9 during light load currents by only switching when it is needed. downloaded from: http:///
micrel inc. mic2315 8/9 november 2012 16 m9999 -1 10812 -a as t he load current increases, the mic23158/9 goes into continuous conduction mode (ccm) and switches at a frequency centered at 3mhz . the equation to calculate the load when the mic2315 8/9 goes into continuous conduction mode may be approximated by the follow ing formula: ? ?? ? ? ?? ? ? > f 2l d ) v (v i out in load eq. 7 as shown in equation 7 , the load at which the mic23158/9 transitions from hyperlight load mode to pwm mode is a function of the input voltage (v in ), output voltage (v out ), duty cycle (d), inductance (l) and fre quency (f). as shown in figure 5 , as the output c urrent increases, the switching frequency also increases until the mic23158/9 goes from hyperlight load mode to pwm mode at approximately 1 8 0ma. the mic23158/9 will switch at a relatively constant frequency around 3mhz once the output current is over 1 8 0ma. switching frequency vs. output current 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 0.1 1 10 100 1000 10000 output current (ma) switching frequency (mhz) l=1.0h l=0.47h figure 5 . sw frequency vs. output curren t downloaded from: http:///
micrel inc. mic2315 8/9 november 2012 17 m9999 -1 10812 -a typical application circuit (adjustable output) bill of materials item part name manufacturer description qty. c1, c 2 06036d105kat2a avx (1) 1f, 0603, 6.3v 2 grm188r60j105ka01d murata (2) c1608x5r0j105k tdk (3) c3, c4, c5, c6 06036d475kat2a avx 4.7f, 6.3v, x5r, 0603 4 grm188r60j475ke19d murata c1608x5r0j475k tdk c7, c8 06035a471jat2a avx 470pf, 50v, 0603 2 grm1885c1h471ja01d murata c1608c0g1h471j tdk l1, l2 cdrh4d28cldnp - 1r0p sumida (4) 1 h, 3.0a, 14m?, l5.1mm x w5.1mm x h3.0mm 2 lqh44pn1r0nj0 murata 1 h, 2.8a, 14m?, l5.1mm x w5.1mm x h3.0mm r1 crcw06033013fkea vishay/dale (5) 301k?, 1%, 1/10w, 0603 1 r2 crcw06031583fkea vishay/dale 158k?, 1%, 1/10w, 0603 1 r3 crcw06033163fkea vishay/dale 316k?, 1%, 1/10w, 0603 1 r4 crcw06032213fkea vishay/dale 221k?, 1%, 1/10w, 0603 1 r5, r6 crcw06031003fkea vishay/dale 100k?, 1%, 1/10w, 0603 2 r7, r8 crcw06031002fkea vishay/dale 10k?, 1%, 1/10w, 0603 2 u1 mic23158/9yml micrel, inc (6) 3mhz pwm du al 2a buck regulator with hyperl ight load and power good 1 notes: 1. avx: www.avx.com . 2. murata: www.murata.com . 3. tdk: www.tdk.com . 4. sumida: www.sumida.com . 5. vishay /dale : www.vishay.com . 6. micrel, inc.: www.micrel.com . downloaded from: http:///
micrel inc. mic2315 8/9 november 2012 18 m9999 -1 10812 -a pcb layout recommendations top layer bottom layer downloaded from: http:///
micrel inc. mic2315 8/9 november 2012 19 m9999 -1 10812 -a package information (1) 20 - pin 3mm x 4 mm mlf note: 1. package information is correct as of the publication date. for updates and most current infor mation, go to www.micrel.com . downloaded from: http:///
micrel inc. mic2315 8/9 november 2012 20 m9999 -1 10812 -a recommended land p attern 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 comp leteness 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 us e. 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 b y this document. except as provided in micrels terms and conditions of sale for such products, mic rel assumes no liability whatsoever, and micrel disclaims any express or implied warranty relating to the sale and/ or use of micrel products including liabi lity or warranties relating to fitness for a particular purpose, merchantability, or infringement of any pat ent, copyright or other intellectual property right. micrel products are not designed or authorized for use as components in life support appl iances, devices or systems where malfunction of a product can reasonably be expected to result in personal injury. life support devices or systems are device s or systems that (a) are intended for surgical imp lant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to res ult in a significant injury to the user. a purchasers use or sale of micrel products for use in life support appliances, devices or systems is a purchasers own risk and purchaser agrees to fully indemnify micrel for any damages resulting from such use or sale. ? 201 2 micrel, incorporated. downloaded from: http:///

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