View MIC26603-ZAYJL_7604400.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

mic26603 - za 28v, 6a hyper speed control ? synchronous dc/dc buck regulator superswitcher ii ? hyper speed control, superswitcher ii, and any capacitor are trademarks 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 may 21, 20 13 revision 1.0 general description the micrel mic26603 - za is a constant - frequency, synchronous buck regulator featuring a unique adaptive on - time control architecture. the mic26603 - za operates over an input supply range of 4.5v to 28v and provides a regulated output of up to 6a of output current. the output voltage is adjustable down to 0.6v with a guaranteed accuracy of 1%, and the device operates at a switching frequency of 600khz. micrel?s hyper speed control ? architecture allows for ultra - fast transient response wh ile reducing the output capacitance and also makes (high v in )/(low v out ) operation possible. this adaptive t on ripple control architecture combines the advantages of fixed - frequency operation and fast transient response in a single device. the mic26603 - za offers a full suite of features to ensure protection of the ic during fault conditions. these include undervoltage lockout to ensure proper operation under power - sag conditions, internal soft - start to reduce inrush current, foldback current limit, ?hiccup mode? short - circuit protection , and thermal shutdown. an open - drain power good (pg) pin is provided. datasheets and support documentation are available on micrel?s web site at : www.micrel.com . features ? hyper speed c ontrol architecture enables ? high delta v operation (v in = 28v and v out = 0.6v) ? small output capacitance ? 4.5v to 28v voltage input ? 6a output current capability, up to 95% efficiency ? adjustable output from 0.6v to 5.5v ? 1% feedback accuracy ? any capacitor ? st able - zero - to - high esr ? 600khz switching frequency ? no external compensation ? power good (pg) output ? foldback current limit and ?hiccup mode? short - circuit protection ? supports safe startup into a pre - biased load ? ? 40 c to +125 c junction temperature range ? 28- pin 5mm 6mm qfn package applications ? distributed power systems ? communications/networking infrastructure ? set - top box, gateways, and routers ? printers, scanners, graphic cards, and video cards typical application 50 55 60 65 70 75 80 85 90 95 100 0 1 2 3 4 5 6 7 8 efficiency (%) output current (a) efficiency (v in = 12v) vs. output current 5.0v 3.3v 2.5v 1.8v 1.5v 1.2v 1.0v 0.9v 0.8v
micrel, inc. mic26603 - za may 2 1 , 20 13 2 revision 1.0 ordering information part number v oltage switching frequency package junction temperature range lead finish mic26603 - zayjl adjustable 600khz 28- pin 5mm 6mm qfn ? 40c to +125c pb - free pin configuration 2 8 - pin 5mm 6mm qfn (jl) (top view)
micrel, inc. mic26603 - za may 2 1 , 20 13 3 revision 1.0 pin description pin number pin name pin function 1 pvdd 5v internal linear regulator output: pvdd supply is the power mosfet gate drive supply voltage created by internal ldo from vin. when vin < +5.5v, pvdd should be tied to the pvin pins. a 2.2f ceramic capacitor from the pvdd pin to pgnd ( p in 2) must be place d next to the ic. 2, 5, 6, 7, 8, 21 pgnd power ground: pgnd is the ground path for the buck converter power stage. the pgnd pins connect to the low - side n - channel internal mosfet gate drive supply ground, the sources of the mosfets, the negative terminals of input capacitors, and the negative terminals of output capacitors. the loop for the power ground should be as small as possible and separate from the s ignal ground (sgnd) loop. 3 nc no connect. 4, 9, 10, 11, 12 sw switch node outpu t : internal connection for the high - side mosfet source and low - side mosfet drain. because of the high - speed switching on this pin, the sw pin should be routed away from sensitive nodes. 13,14,15,16, 17,18,19 pvin high - side n - internal mosfet drain connectio n input : the pvin operating voltage range is from 4.5v to 28v. input capacitors between the pvin pins and the p ower g round (pgnd) are required and keep the connection short. 20 bst boost output : bootstrapped voltage to the high - side n - channel mosfet driver. a schottky diode is connected between the pvdd pin and the bst pin. a boost capacitor of 0.1f is connected between the bst pin and the sw pin. adding a small resistor at the bst pin can reduce the turn - on time of high - side n - channel mosfets. 22 cs cur rent sense input: the cs pin senses current by monitoring the voltage across the low - side mosfet during the off - time. the current sensing is necessary for short circuit protection. t o sense the current accurately, connect the low - side mosfet drain to sw us ing a kelvin connection. the cs pin is also the high - side mosfet?s output driver return. 23 sgnd signal ground : sgnd must be connected directly to the ground planes. do not route the sgnd pin to the pgnd p ad on the top layer (see ? pcb layout guidelines ? for details). 24 fb feedback input : input to the transconductance amplifier of the control loop. the fb pin is regulated to 0.6v. a resistor divider connecting the feedback to the output is used to adjust the desir ed output voltage. 25 pg power good output : open drain output. the pg pin is externally tied with a resistor to vdd. a high output is asserted when v out > 92% of nominal. 26 en enable input : a logic level control of the output. the en pin is cmos - compati ble. logic high = enable, logic low = shutdown. in the off state, the supply current of the device is gr eatly reduced (typically 5a). do not leave t he en pin floating. 27 vin power supply voltage input : requires a bypass capacitor to sgnd. 28 vdd 5v int ernal linear regulator outpu t : vdd supply is the power mosfet gate drive supply voltage and the supply bus for the ic. vdd is created by internal ldo from vin. when vin < +5.5v, vdd should be tied to pvin pins. a 1f ceramic capacitor from the vdd pin to s gnd pins must be place d next to the ic.
micrel, inc. mic26603 - za may 2 1 , 20 13 4 revision 1.0 absolute maximum ratings ( 1 ) pvin to pgnd ............................................... ? 0.3v to +29v vin to pgnd ................................................. ? 0.3v to pvin pvdd, vdd to pgnd ..................................... ? 0.3v to +6v v sw , v cs to pgnd ............................. ? 0.3v to (pvin +0.3v) v bst to v sw ........................................................ ? 0.3v to 6v v bst to pgnd .................................................. ? 0.3v to 35v v fb , v pg to pgnd ............................. ? 0.3v to (vdd + 0.3v) v en to pgnd ....................................... ? 0.3v to (vin +0.3v) pgnd to sgnd ............................................ ? 0.3v to +0.3v junction temperature .............................................. +150c storage temperature (t s ) ......................... ? 65 c to +150 c lead temperature (soldering, 10s) ............................ 260c esd rating ( 3) ................................................. esd sensitive operating ratings ( 2 ) supply voltage (pv in , v in ) .............................. 4.5v to 28v pvdd, vdd supply voltage ............................ 4.5v to 5.5v enable input (v en ) .................................................. 0v to v in junction temperature (t j ) ........................ ? 40 c to +125 c maximum power dissipation ...................................... note 4 package thermal resistance (4) 5mm x 6mm qfn ( ja ) ..................................... 28 c/w electrical characteristics ( 5 ) pvin = vin = v en = 12v, v bst ? v sw = 5v; t a = 25 c, unless noted. bold values indicate ? 40c t j +125 c. parameter condition min. typ. max. units power supply input input voltage range (vin, pvin) 4.5 28 v quiescent supp ly current v fb = 1.5v (non - switching) 730 1500 a shutdown supply current v en = 0v 5 10 a vdd supply voltage vdd output voltage vin = 7v to 28v, i dd = 40ma 4.8 5 5.4 v vdd uvlo threshold vdd rising 3.7 4.2 4.5 v vdd uvlo hysteresis 400 mv drop out voltage (vin ? vdd) i dd = 25ma 380 600 mv dc/dc controller output voltage adjust range (v out ) ? 40c t j 85c 0.6 5.5 v reference feedback voltage 0 c t j 85 c, 1.0% 0.594 0.6 0.606 v ? 40c t j 125 c, 1.5% 0.591 0.6 0.609 load regu lation i out = 0a to 6a (continuous mode) 0.25 % line regulation vin = 4.5v to 28v 0.25 % fb bias current v fb = 0.6v 50 na notes: 1. exceeding the absolute maximum ratings may damage the device. 2. the device is not guaranteed to function outside its ope rating ratings. 3. devices are esd sensitive. handling precautions are recommended. human body model, 1.5k in series with 100pf. 4. pd (max) = (t j(max) ? t a )/ ja , where ja depends upon the printed circuit layout. a 5 - in 2 4 layer, 0.62?, fr - 4 pcb with 2oz finish copper weight per layer is used for the ja . 5. specification is for packaged product only .
micrel, inc. mic26603 - za may 2 1 , 20 13 5 revision 1.0 electrical characteristics ( 5 ) (continued) pvin = vin = v en = 12v, v bst ? v sw = 5v; t a = 25 c, unless noted. bold values indicate ? 40c t j +125 c. parameter condition min. typ. max. units enable control en logic level high 1.8 v en logic level low 0.6 v en bias current v en = 12v 6 30 a oscillator switching frequency ( 6 ) 450 600 750 khz maximum duty cycle ( 7 ) v fb = 0v 82 % minimum duty cycle v fb = 1.0v 0 % minimum off - time 300 n s soft - start soft - start time 5 ms short - circuit protection current - limit thre shold v fb = 0.6v, t j = 25 c 7.5 13 17 a current - limit threshold v fb = 0.6v, t j = 125 c 6.6 13 17 a short - circuit current v fb = 0v 2.7 a internal fets top - mosfet r ds (on) i sw = 1a 42 m ? bottom - mosfet r ds (on) i sw = 1a 12.5 m ? sw leakage current v en = 0v 60 a v in leakage current v en = 0v 25 a power good ( pg ) pg threshold voltage sweep v fb from l ow to h igh 85 92 95 %v out pg hysteresis sweep v fb from h igh to l ow 5.5 %v out pg delay time sweep v fb from l ow to h igh 100 s pg low voltage sweep v fb < 0.9 v nom , i pg = 1ma 70 200 mv thermal protection over t emperature shutdown t j rising 160 c over t emperature shutdown hysteresis 15 c notes: 6. measured in test mode. 7. the maximum duty - cycle is limited by the fixed mandatory off - time t off , typically 300ns.
micrel, inc. mic26603 - za may 2 1 , 20 13 6 revision 1.0 typical characteristics 0 4 8 12 16 20 4 10 16 22 28 supply current (ma) input voltage (v) v in operating supply current vs. input voltage v out = 1.8v i out = 0a switching 0 15 30 45 60 4 10 16 22 28 shutdown current (a) input voltage (v) v in shutdown current vs. input voltage v en = 0v r en = open 0 2 4 6 8 10 4 10 16 22 28 vdd voltage (v) input voltage (v) v dd output voltage vs. input voltage v fb = 0.9v i dd = 10ma 0.592 0.596 0.600 0.604 0.608 4 10 16 22 28 feedback voltage (v) input voltage (v) feedback voltage vs. input voltage v out = 1.8v i out = 0a -1.0% -0.5% 0.0% 0.5% 1.0% 4 10 16 22 28 total regulation (%) input voltage (v) total regulation vs. input voltage v out = 1.8v i out = 0a to 6a 0 5 10 15 20 4 10 16 22 28 current limit (a) input voltage (v) current limit vs. input voltage v out = 1.8v 500 550 600 650 700 4 10 16 22 28 frequency (khz) input voltage (v) switching frequency vs. input voltage v out = 1.8v i out = 0a 0 4 8 12 16 4 10 16 22 28 en input current (a) input voltage (v) enable input current vs. input voltage v en = v in 80% 85% 90% 95% 100% 4.0 10.0 16.0 22.0 28.0 vpg threshold/vref (%) input voltage (v) pg/v ref ratio vs. input voltage v ref = 0.6v
micrel, inc. mic26603 - za may 2 1 , 20 13 7 revision 1.0 typical characteristics (continued) 0 4 8 12 16 20 -50 -25 0 25 50 75 100 125 supply current (ma) temperature ( c) v in operating supply current vs. temperature v in = 12v v out = 1.8v i out = 0a switching 0 5 10 15 20 -50 -25 0 25 50 75 100 125 supply current (a) temperature ( c) v in shutdown current vs. temperature v in = 12v i out = 0a v en = 0v 0 1 2 3 4 5 -50 -25 0 25 50 75 100 125 vdd threshold (v) temperature ( c) v dd uvlo threshold vs. temperature rising falling hyst 0.592 0.596 0.600 0.604 0.608 -50 -25 0 25 50 75 100 125 feeback voltage (v) temperature ( c) feedback voltage vs. temperature v in = 12v v out = 1.8v i out = 0a -1.0% -0.5% 0.0% 0.5% 1.0% -50 -25 0 25 50 75 100 125 load regulation (%) temperature ( c) load regulation vs. temperature v in = 12v v out = 1.8v i out = 0a to 6a 0.0% 0.1% 0.2% 0.3% 0.4% -50 -25 0 25 50 75 100 125 line regulation (%) temperature ( c) line regulation vs. temperature v in = 4.5v to 28v v out = 1.8v i out = 0a 500 550 600 650 700 -50 -25 0 25 50 75 100 125 frequency (khz) temperature ( c) switching frequency vs. temperature v in = 12v v out = 1.8v i out = 0a 2 3 4 5 6 -50 -25 0 25 50 75 100 125 v dd (v) temperature ( c) v dd vs. temperature v in = 12v i out = 0a 0 5 10 15 20 25 -50 -25 0 25 50 75 100 125 current limit (a) temperature ( c) current limit vs. temperature v in = 12v v out = 1.8v
micrel, inc. mic26603 - za may 2 1 , 20 13 8 revision 1.0 typical characteristics (contin ued) 50 55 60 65 70 75 80 85 90 95 0 1 2 3 4 5 6 efficiency (%) output current (a) efficiency vs. output current 12v in 24v in v out = 1.8v 0.592 0.596 0.600 0.604 0.608 0 1 2 3 4 5 6 feedback voltage (v) output current (a) feedback voltage vs. output current v in = 12v v out = 1.8v 1.782 1.787 1.791 1.796 1.800 1.805 1.810 1.814 1.819 0 1 2 3 4 5 6 output voltage (v) output current (a) output voltage vs. output current v in = 12v v out = 1.8v -1.0% -0.5% 0.0% 0.5% 1.0% 0 1 2 3 4 5 6 line regulation (%) output current (a) line regulation vs. output current v in = 4.5v to 28v v out = 1.8v 500 550 600 650 700 0 1 2 3 4 5 6 frequency (khz) output current (a) switching frequency vs. output current v in = 12v v out = 1.8v 3 3.4 3.8 4.2 4.6 5 0 1 2 3 4 5 6 7 8 output voltage (v) output current (a) output voltage (v in = 5v) vs. output current t a 25oc 85oc 125oc v in = 5v v fb < 0.6v 50 55 60 65 70 75 80 85 90 95 100 0 1 2 3 4 5 6 7 8 efficiency (%) output current (a) efficiency (v in = 5v) vs. output current (d01) 3.3v 2.5v 1.8v 1.5v 1.2v 1.0v 0.9v 0.8v ic power dissipation (v in = 5v) vs. output current 0.0 0.5 1.0 1.5 2.0 2.5 0 1 2 3 4 5 6 output current (a) ic power dissipation (w) v in = 5v v out = 0.8,v, 1.0v, 1.2v, 1.5v, 1.8v,2.5v, 3.3v 3.3v 0.8v 0 10 20 30 40 50 60 0 1 2 3 4 5 6 die temperature ( c) output current (a) die temperature* (v in = 5v) vs. output current v in = 5v v out = 1.8v die temperature* : the temperature measurement was taken at the hottest point on the mic26 6 03- za while it was case mounted on a 5in 2 4 - layer, 0.62?, fr - 4 pcb , with 2oz finish copper weight per layer . s ee the ? thermal measurements ? section for more details . actual results will depend on the size of the pcb, ambient temperature , and proximity to other heat emitting components.
micrel, inc. mic26603 - za may 2 1 , 20 13 9 revision 1.0 typical characteristics (continued) 50 55 60 65 70 75 80 85 90 95 100 0 1 2 3 4 5 6 7 8 efficiency (%) output current (a) efficiency (v in = 12v) vs. output current 5.0v 3.3v 2.5v 1.8v 1.5v 1.2v 1.0v 0.9v 0.8v 0.0 0.5 1.0 1.5 2.0 2.5 0 1 2 3 4 5 6 ic power dissipation (w) output current (a) ic power dissipation (v in = 12v) vs. output current v in = 12v v out = 0.8v, 1.0v, 1.2v, 1.5v, 1.8v, 2.5v, 3.3v, 5.0v 5.0v 0.8v 0 10 20 30 40 50 60 0 1 2 3 4 5 6 die temperature ( c) output current (a) die temperature* (v in = 12v) vs. output current v in = 12v v out = 1.8v 50 55 60 65 70 75 80 85 90 95 0 1 2 3 4 5 6 7 8 efficiency (%) output current (a) efficiency (v in = 24v) vs. output current 5.0v 3.3v 2.5v 1.8v 1.5v 1.2v 1.0v 0.9v 0.8v 0.0 0.5 1.0 1.5 2.0 2.5 0 1 2 3 4 5 6 ic power dissipation (w) output current (a) ic power dissipation (v in = 24v) vs. output current v in = 24v v out = 0.8v, 1.0v, 1.2v, 1.5v, 1.8v, 2.5v, 3.3v, 5.0v 5.0v 0.8v 0 10 20 30 40 50 60 0 1 2 3 4 5 6 die temperature ( c) output current (a) die temperature* (v in = 24v) vs. output current v in = 24v v out = 1.8v thermal derating* vs. ambient temperature 0 2 4 6 8 10 12 -50 -25 0 25 50 75 100 125 ambient temperature (c) output current (a) 1.5v v in = 5v v out = 0.8, 1.2, 1.5v 0.8v thermal derating* vs. ambient temperature 0 2 4 6 8 10 12 -50 -25 0 25 50 75 100 125 ambient temperature (c) output current (a) v in = 5v v out = 1.8, 2.5, 3.3v 3.3v 1.8v thermal derating* vs. ambient temperature 0 2 4 6 8 10 12 -50 -25 0 25 50 75 100 125 ambient temperature (c) output current (a) 1.8v 0.8v v in = 12v v out = 0.8, 1.2, 1.8v die temperature* : the temperature measurement was taken at the hottest point on the mic26 6 03- za while it was case mounted on a 5in 2 4 - layer, 0.62?, fr - 4 pcb , with 2oz finish copper weight per layer . s ee the ? thermal measurements ? section for more details . actual results will depend on the size of the pcb, ambient temperature , and proximity to other heat emitting components.
micrel, inc. mic26603 - za may 2 1 , 20 13 10 revision 1.0 typical characteristics (continued) thermal derating* vs. ambient temperature 0 2 4 6 8 10 12 -50 -25 0 25 50 75 100 125 ambient temperature (c) output current (a) 5v 2.5v v in = 12v v out = 2.5, 3.3, 5v thermal derating* vs. ambient temperature 0 2 4 6 8 10 12 -50 -25 0 25 50 75 100 125 ambient temperature (c) output current (a) v in = 24v v out = 0.8, 1.2, 2.5v 2.5v 0.8v die temperature* : the temperature measurement was taken at the hottest point on the mic26 6 03- za while it was case mounted on a 5in 2 4 - layer, 0.62?, fr - 4 pcb , with 2oz finish copper weight per layer . s ee the ? thermal measurements ? section for more details . actual results will depend on the size of the pcb, ambient temperature , and proximity to other heat emitting components.
micrel, inc. mic26603 - za may 2 1 , 20 13 11 revision 1.0 functional characteristics
micrel, inc. mic26603 - za may 2 1 , 20 13 12 revision 1.0 functional characteristics (continued)
micrel, inc. mic26603 - za may 2 1 , 20 13 13 revision 1.0 functional characteristics (continued)
micrel, inc. mic26603 - za may 2 1 , 20 13 14 revision 1.0 functional diagram figure 1 . mic26603 - za block diagram
micrel, inc. mic26603 - za may 2 1 , 20 13 15 revision 1.0 functional description the mic26603 - za is an adaptive o n - time synchronous step - down dc - dc regulator with an internal 5v lin ear regulator and a power good (pg) output. it is designed to operate over a wide input voltage range from 4.5v to 28v and provides a regulated output voltage at up to 7a of output current. an adaptive on - time control scheme is used to get a constant switc hing frequency and to simplify the control compensation. overcurrent protection is implemented without using an external sense resistor. the device includes an internal soft - start function that reduces the power supply input surge current at start - up by co ntrolling the output voltage rise time. theory of operation the mic26603 - za operates in a continuous mode , as shown in figure 1 . continuous mode in continuous mode, the output voltage is sensed by the mic26603 - za f eedback pin fb through the voltage divider r1 and r2 . it is then compared to a 0.6v reference voltage v ref at the error comparator through a low - gain transconductance (g m ) amplifier. if the feedback voltage decreases and the output of the g m amplifier is b elow 0.6v, then the error comparator will trigger the control logic and generate an on - time period. the on - time period length is predetermined by the ?fixed t on estimation? circuitry: khz 600 v v t in out ) estimated ( on = eq. 1 where v out is the output voltage and v in i s the power stage input voltage. at the end of the on - time period, the internal high - side driver turns off the high - side mosfet and the low - side driver turns on the low - side mosfet. the o ff - time period length depends on the feedback voltage in most cases. when the feedback voltage decreases and the output of the g m amplifier is below 0.6v, the on - time period is triggered and the off - time period ends. if the off - time period determined by the feedback voltage is less than the minimum off - time t off(min) , whic h is about 300ns, the mic26603 - za control logic will apply the t off(min) instead. t off(min) is required to maintain enough energy in the boost capacitor (c bst ) to drive the high - side mosfet. the maximum duty cycle is derived from the 300ns t off(min) : s s ) min ( off s max t ns 300 1 t t t d ? = ? = eq. 2 where t s = 1/600khz = 1.66 s. using mic26603 - za with a n off - time close to t off(min) during steady - state operation is not recommended . also, as v out increases, the internal ripple injection increase s and reduce s the line regulati on performance. therefore, the maximum output voltage of the mic26603 - za should be limited to 5.5v and the maximum external ripple injection should be limited to 200mv. please refer to the ? setting output voltage ? subsection in application information for more details. the actual on - time and resulting switching frequency will vary with the part - to - part variation in the rise and fall times of the internal mosfets, the output load current, and variations in the v dd voltage. also, the minimum t on results in a lower switching frequency in high v in to v out applications, such as 24v to 1.0v. the minimum t on measured on the mic26603 - za evaluation board is about 100ns. during load tr ansients, the switching frequency is changed because of the varying off - time. to illustrate the control loop operation, the datasheet will discuss both the steady - state and load transient scenarios. figure 2 shows the mic26603 - za control loop timing during steady - state operation. during steady - state operation , the g m amplifier senses the feedback voltage ripple, which is proportional to the output voltage ripple and the inductor current ripple, to trigger the on - ti me period. the on - time is predetermined by the t on estimator. the termination of the off - time is controlled by the feedback voltage. at the valley of the feedback voltage ripple, which occurs when v fb falls below v ref , the off - time period ends and the next on - time period is triggered through the control logic circuitry.
micrel, inc. mic26603 - za may 2 1 , 20 13 16 revision 1.0 figure 2 . mic26603- za control loop timing figure 3 shows the operation of the mic26603 - za during a load transient. the output voltage drops because of the sudden load increase, which makes the v fb less than v ref . this cause s 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 c bst because the feedback voltage is still below v ref . then, the next on - time period is triggered by the low feedback voltage. therefore, the switching frequency changes during the load transient, but returns to the nominal fixed frequency after the output has stabili zed at the new load current level. with the varying duty cycle and switching frequency, the output recovery time is fast and the output voltage deviation is small in a mic26603 - za converter. figure 3 . mic26603 - za load transient response unlike true current - mode control, the mic26603 - za 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. the mic26 603 - za control loop has the advantage of eliminating the need for slope compensation. t o meet the stability requirements, the mic26603 - za feedback voltage ripple should be in phase with the inductor current ripple and large enough to be sensed by the g m a mplifier and the error comparator. the recommended feedback voltage ripple is 20mv~100mv. 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 outp ut voltage ripple and the feedback voltage ripple are not necessarily in phase with the inductor current ripple if the esr of the output capacitor is very low. in these cases, ripple injection is required to ensure proper operation. please refer to the ? ripple injection ? subsection in application information for more details about the ripple injection technique. vdd regulator the mic26603 - za provides a 5v regulated output for input voltage v in ranging from 5.5v to 28v. when v in < 5.5v, vdd should be tied to pvin pins to bypass the internal linear regulator. soft - start soft - start reduces the power supply input 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 draw s a lower input surge current. the mic26603 - za implements an internal digital soft - start by making the 0.6v reference voltage v ref ramp from 0 to 100% in about 6ms in 9.7mv steps. therefore, the output voltage is controlled to increase slowly by a stair - case v fb ramp. after the soft - start cycle ends, the related circuitry is disabled to reduce current consumption. v dd must be powered up at the same time or after vin to make the soft - start function correctly. current limit the mic26603 - za uses the r ds(on) of the internal low - side power mosfet to sense overcurrent conditions. this method avoid s adding cost, board space , and power losses taken by a discrete cu rrent sense resistor. the low - side mosfet is used because it displays much lower parasitic oscillations during switching than the high - side mosfet.
micrel, inc. mic26603 - za may 2 1 , 20 13 17 revision 1.0 in each switching cycle of the mic26603 - za converter, the inductor current is sensed by monitoring the low - side mosfet in the off - time period. if the peak inductor current is greater than 13a, then the mic26603 - za turns off the high - side mosfet and a soft - start sequence is triggered. this mode of operation is called ?hiccup mode? and its purpose is to protect t he downstream load in case of a hard short. the load cur rent - limit threshold has a fold back characteristic related to the feedback voltage , as shown in figure 4 . current limit threshold vs. feedback voltage 0 4 8 12 16 20 0.0 0.2 0.4 0.6 0.8 1.0 feedback voltage (v) current limit threshold (a) figure 4 . mic26603- za current - limit foldback characteristic power good (pg) the power good (pg) pin is an open - drain output that indicates logic high when the output is nominally 92% of its steady state voltage. a pull - up resistor of more than 10k should be connected from pg to vdd. mosfet gate drive the block diagram ( figure 1 ) shows a bootstrap circuit, consisting of d1 (a schottky diode is recommended) and c bst . this circuit supplies energy to the high - side drive circuit. capacito r c bst is charged, while the low - side mosfet is on, and the voltage on the sw pin is approximately 0v. when the high - side mosfet driver is turned on, energy from c bst is used to turn the mosfet on. as the high - side mosfet turns on, the voltage on the sw pi n increases to approximately v in . diode d1 is reverse biased and c bst floats high while continuing to keep the high - side mosfet on. the bias current of the high - side driver is less than 10ma so a 0.1f to 1f capacitor is enough to hold the gate voltage wi th minimal droop for the power stroke ( high - side switching) cycle, that is, bst = 10ma 1.67s/0.1f = 167mv. when the low - side mosfet is turned back on, c bst is recharged through d1. a small resistor r g , in series with c bst , can be used to slow down the turn - on time of the high - side n - channel mosfet. the drive voltage is derived from the v dd supply voltage. the nominal low - side gate drive voltage is v dd and the nominal high - side gate drive voltage is approximately v dd ? v diode , where v diode is the voltag e drop across d1. an approximate 30ns delay between the high - side and low - side driver transitions is used to prevent current from simultaneously flowing unimpeded through both mosfets.
micrel, inc. mic26603 - za may 2 1 , 20 13 18 revision 1.0 application information inductor selection values for inductance, pe ak, and rms currents are required to select the output inductor. the input and output voltages and the inductance value determine the peak - to - peak inductor ripple current. generally, higher inductance values are used with higher input voltages. larger peak - to - peak ripple currents increase the power dissipation in the inductor and mosfets. larger output ripple currents also require more output capacitance to smooth out the larger ripple current. smaller peak - to - peak ripple currents require a larger inductanc e value and therefore a larger and more expensive inductor. a good compromise between size, loss , and cost is to set the inductor ripple current equal to 20% of the maximum output current. the inductance value is calculated in equation 3. ) max ( out sw ) max ( in out ) max ( in out i % 20 f v ) v v ( v l ? = eq. 3 where: f sw = switching frequency, 600khz 20% = ratio of ac ripple current to dc output current v in(max) = maximum power stage input voltage the peak - to - peak inductor current ripple is: l f v ) v v ( v i sw ) max ( in out ) max ( in out ) pp ( l ? = ? eq. 4 the peak inductor current is equal to the average output current plus one half of the peak - to - peak inductor current ripple. ) pp ( l ) max ( out ) pk ( l i 5 . 0 i i ? + = eq. 5 the rms inductor current is used to calculate the i 2 r losses in the inductor. 12 i i i 2 ) pp ( l 2 ) max ( out ) rms ( l ? + = eq. 6 maximizing efficiency requires the selecting the proper core material and minimizing the winding resistance. the high - frequency operation of the mic26603 - za requires the use of ferrite materials for all but the most cost - sensitive applications. lower - cost iron powder cores may be used but the increase in core loss reduce s the efficiency of the power supply. this is especially noticeable at low output power. the winding resistance decreases efficiency at the higher output current levels. the winding resistance must be minimized , although this usually comes at the expense of a larger inductor. the power dissipated in the inductor is equal to the sum of the core and copper losses. at higher output loads, the core losses are usually insignificant and can be ignored. at lower output c urrents, the core losses can be a significant contributor. core loss information is usually available from the magnetics vendor. copper loss in the inductor is calculated by equation 7. winding 2 ) rms ( l ) cu ( inductor r i p = eq. 7 the resistance of the copper wire, r wind ing , increases with the temperature. the value of the winding resistance used should be at the operating temperature. )) t t ( 0042 . 0 1 ( r p c 20 h ) c 20 ( winding ) ht ( winding ? + = eq. 8 where: t h = temperature of wire under full load t 20c = ambient temperature r winding(20c) = room temperatur e winding resistance (usually specified by the manufacturer) output capacitor selection the type of output capacitor is usually determined by its equivalent series resistance (esr). voltage and rms current capability are two other important factors . recomm ended capacitor types are ceramic, low - esr aluminum electrolytic, os - con and poscap. the output capacitor?s esr is usually the main cause of the output ripple. the output capacitor esr also affects the stability of the control loop. the maximum value of e sr is calculated using equation 9. ) pp ( l ) pp ( out c i v esr out ? ? eq. 9 where: v out(pp) = peak - to - peak output voltage ripple ?, l(pp) = peak - to - peak inductor current ripple
micrel, inc. mic26603 - za may 2 1 , 20 13 19 revision 1.0 the total output ripple is a combination of the esr and output capacitance. the total ripp le is calculated in equation 10. ( ) 2 c ) pp ( l 2 sw out ) pp ( l ) pp ( out out esr i 8 f c i v ? + ? ? ? ? ? ? ? ? ? = ? eq. 10 where: d = duty cycle c out = output capacitance value f sw = switching frequency as described in the ? theory of operation ? subsection in functional description , the mic26603 - za 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 indu ctor current. therefore, the output voltage ripple caused by the output capacitors value should be much smaller than the ripple caused by the 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 b e twice the outpu t voltage for tantalum and 20% greater for aluminum electrolytic or os - con. the output capacitor rms curre nt is calculated in equation 11. 12 i i ) pp ( l ) rms ( c out ? = eq. 11 the power dissipated in the output capacitor is: out out out c 2 (rms) c ) diss(c esr i p = eq. 12 input cap acitor selection the input capacitor for the power stage input v 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 derating . the input voltage ripple primarily depend s on the input capacitor?s esr. the peak input current is equal to the peak inductor current, so: in c ) pk ( l in esr i v = ? eq. 13 the input capacitor must be rated for the input current ripple. the rms value of input capacito r current is determined at the maximum output current. assuming the peak - to - peak inductor current ripple is low: ) d 1 ( d i ) rms ( i ) max ( out c in ? eq. 14 the power dissipated in the input capacitor is: in in in c ) rms ( c ) c ( diss esr i p = eq. 15 ripple injection the v fb ripple r equired for proper operation of the mic26603 - za 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 rippl e is only 10mv to 20mv, and the feedback voltage ripple is less than 20mv. if the feedback voltage ripple is so small that the g m amplifier and error comparator can?t sense it, then the mic26603 - za will lose control and the output voltage is not regulated. in order to have some amount of v fb ripple, a ripple injection method is applied for low output voltage ripple applications. the applications are divided into three situations according to the amount of the feedback voltage ripple: 1. enough ripple at the fe edback voltage caused by the large esr of the output capacitors. as shown in figure 5 , the converter is stable without any ripple injection. the feedback voltage ripple is: ) pp ( l c ) pp ( fb i esr 2 r 1 r 2 r v out ? + = ? eq. 16 where i l( pp) is the peak - to - peak value of the inductor current ripple. 2. inadequate ripple at the feedback voltage caused by the small esr of the output capacitors. the output voltage ripple is fed into the fb pin through a feedforward capacitor c ff in this situation , as shown in figure 6 . the typical c ff value is between 1nf and 100nf. with the feedforward capacitor, the feedback voltage ripple is very close to the output voltage ripple: ) pp ( l ) pp ( fb i esr v ? ? eq. 17 3. virtual ly no ripple at the fb pin voltage due to the very - low esr of the output capacitors.
micrel, inc. mic26603 - za may 2 1 , 20 13 20 revision 1.0 figure 5 . enough ripple at fb figure 6 . inadequate ripple at fb figure 7 . invisible ripple at fb 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 7 . the injected ripple is: ? = ? sw div in ) pp ( fb f 1 ) d 1 ( d k v v eq. 18 2 r // 1 r r 2 r / 1 r k inj div + = eq. 19 where : v in = p ower stage input voltage d = d uty cycle f sw = s witching frequency = (r1//r2//r inj ) 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 fsw 1 << = eq. 20 ,i wkh yrowdjh glylghu uhvlvwruv 5 dqg 5 duh lq wkh n range, a c ff of 1nf to 100nf can easily satisfy the large time constant requirements. also , a 100nf injection capacitor c inj is used , which could be considered as short for a wide range of the frequencies . the process of sizing the ripple injection resistor and capacitors 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 r2 are lqn udqjh step 2. select r inj according to the expected feedback voltage ripple using equation 19. ) d 1 ( d f v v k sw in ) pp ( fb div ? ? = eq. 21 then the value of r inj is obtained as: ? ? ? ? ? ? ? ? ? = 1 k 1 ) 2 r // 1 r ( r div inj eq. 22 step 3. select c inj as 100nf, which could be conside red as short for a wide range of the frequencies. setting output voltage the mic26603 - za requires two resistors to set the output voltage , as shown in figure 8 . the output voltage is determined by equation 23: ? ? ? ? ? ? + = 2 r 1 r 1 v v fb out eq. 23 where v fb = 0.6v. a typical va oxh ri 5 fdq eh ehwzhhq n dqg n ,i r1 is too large, it may allow noise to be introduced into the voltage feedback loop. if r1 is too small, it will decrease the efficiency of the power supply, especially at light loads. once r1 is selected, r2 can b e calculated using equation 24. fb out fb v v 1 r v 2 r ? = eq. 24
micrel, inc. mic26603 - za may 2 1 , 20 13 21 revision 1.0 figure 8 . voltage - divider configuration in addition to the external ripple injection added at the fb pin, internal ripple injection is added at the inverting input of the comparator inside the mic26603 - za, as shown in figure 9 . the inverting input voltage v inj is clamped to 1.2v. as v out increase s , the swing of v inj is clamped. the clamped v inj reduces the line regulation be cause it is reflected as a dc error on the fb terminal. therefore, the maximum output voltage of the mic26603 - za should be limited to 5.5v to avoid this problem. figure 9 . internal ripple injection thermal measurements measuri ng the ic?s case temperature is recommended to e nsure that it is within its operating limits. although this might seem like a n elementary task, it is easy to get false results. the most common mistake is to use the standard thermal couple that comes 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 thermometer. if a thermal couple wire is used, 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 sure 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 t hermometers is too large for an accurate re ading on a small form factor ic . 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 be am on the ic for long periods of time.
micrel, inc. mic26603 - za may 2 1 , 20 13 22 revision 1.0 pcb layout guidelines note: to minimize emi and output noise, follow these layout recommendations. pcb layout 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. follow these guidelines to ensure proper mic26603 - za regulator operation: ic ? a 2.2f ceramic capacitor, which is connected to the pvdd pin, must be located right at the ic. the pvdd pin i s very noise sensitive , so placement of the capacitor is critical. use wide traces to connect to the pvdd and pgnd pins. ? a 1f ceramic capacitor must be placed right between vdd and the signal ground (sgnd). sgnd must be connected directly to the ground pl anes. do not route the sgnd pin to the pgnd p ad 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. ? keep signal and power grounds separate and connected at only one location. input cap acitor ? place the input capacitor next. ? place the input capacitor on the same side of the board and as close to the ic as possible. ? keep both the pvin pin and pgnd connections short. ? 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 must 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 overvoltage spike seen on the input supply when power is suddenly applied. inductor ? keep the inductor connection to the switch node (sw) short. ? do not route any digital lines underneath or close to the inductor. ? keep the switch node (sw) away from the feedback (fb) pin. ? connect the cs pin directly to the sw pin to accurately sense the voltage across the low - side mosfet. ? to minimize noise, place a ground plane underneath the inductor. ? the inductor can be placed on the opposite si de of the pcb with respect to the ic. it does not matter whether the ic or inductor is on the top or bottom as long as there is enough air flow to keep the power components within their temperature limits. the input and output capacitors must be placed on the same side of the board as the ic. output capacitor ? use a wide trace to connect the output capacitor ground terminal to the input capacitor ground terminal. ? phase margin changes as the output capacitor value and esr changes. contact the factory if the o utput capacitor is different from what is shown in the bom. ? the feedback trace should be separate from the power trace and connected as near as possible to the output capacitor. sensing a long high current load trace can degrade the dc load regulation. opt ional rc snubber ? place the rc snubber on either side of the board and as close to the sw pin as possible.
micrel, inc. mic26603 - za may 2 1 , 20 13 23 revision 1.0 evaluation board schematic figure 10 . schematic of mic26603 - za evaluation board (j11, r13, r15 are for testing purpos es)
micrel, inc. mic26603 - za may 2 1 , 20 13 24 revision 1.0 bill of materials item part number manufacturer description qty. c1 open c2, c3 12105c475kaz2a avx ( 8 ) 4.7f ceramic capacitor, x7r, size 1210, 50v 2 grm32er71h475ka88l murata ( 9 ) c3225x7r1h475k tdk ( 10) c4, c13, c15 open c5 12106d107mat2a avx 100f ceramic capacitor, x5r, size 1210, 6.3v 1 grm32er60j107me20l murata c3225x5r0j107m tdk c6, c7, c 10 06035c104kat2a avx 0.1f ceramic capacitor, x7r, size 0603, 50v 3 grm188r71h104ka93d murata c1608x7r1h104k tdk c8 0603zc105kat2a avx 1.0f ceramic capacitor, x7r, size 0603, 10v 1 grm188r71a105ka61d murata c1608x7r1a105k tdk c9 0603zd2 25kat2a avx 2.2f ceramic capacitor, x5r, size 0603, 10v 1 grm188r61a225ke34d murata c1608x5r1a225k tdk c12 06035c472kaz2a avx 4.7nf ceramic capacitor, x7r, size 0603, 50v 1 grm188r71h472k murata c1608x7r1h472k tdk c14 b41851f7227m epcos ( 11) 220f aluminum capacitor, 35 v 1 c11, c16 open d1 sd103aws mcc ( 12) 40v, 350ma, schottky diode, sod323 1 sd103aws -7 diodes inc. ( 13 ) sd103aws vishay ( 14 ) l1 hcf1305 - 2r2 -r cooper bussmann ( 15 ) 2.2h inductor, 15a saturation current 1 r1 crcw06032r21fkea vishay dale 2.21 ? re sistor, size 0603, 1% 1 r2 crcw06032r00fkea vishay dale 2.00 ? resistor , size 0603, 1% 1 r3 crcw060319k6fkea vishay dale 19.6k ? resistor, size 0603, 1% 1 r4 crcw06032k49fkea vishay dale 2.49k ? resistor, size 0603, 1% 1 r5 crcw06034k99fkea vishay dale 4. 99k ? resistor, size 0603, 1% 1 notes: 8. avx: www.avx.com . 9. murata: www.murata.com . 10. tdk: www.tdk.com . 11. epcos: w ww.epcos.com . 12. mcc: www.mccsemi.com . 13. diode s inc.: www.diodes.com . 14. vishay: www.vishay.com . 15. cooper bussmann: www.cooperbussmann.com .
micrel, inc. mic26603 - za may 2 1 , 20 13 25 revision 1.0 bill of materials (continued) item part number manufacturer description qty. r6 crcw06033k74fkea vishay dale 3.74k ? resistor, size 0603, 1% 1 r7 crcw06032k49fkea vishay dale 2.49k ? resistor, size 0603, 1% 1 r8 crcw06031k65fkea vishay dale 1.65k ? resistor, size 0603, 1% 1 r9 crcw06031k24fkea vishay dale 1.24k ? resistor, size 0603, 1% 1 r10 crcw0603787rfkea vishay d ale 787? resistor, size 0603, 1% 1 r11 crcw0603549rfkea vishay dale 549? resistor, size 0603, 1% 1 r 12 crcw0603340r fkea vishay dale 340 ? resistor, size 0603, 1% 1 r13 crcw06030000fkea vishay dale 0? resistor, size 0603, 5% 1 r14, r17 crcw060310k0fkea vishay dale 10.0k? resistor, size 0603, 1% 2 r15 crcw060349r9fkea vishay dale 49.9? resistor, size 0603, 1% 1 r16, r18 crcw06031r21fkea vishay dale 1.21? resistor, size 0603, 1% 2 r20 open u1 mic26603 - zayjl micrel. inc. ( 16 ) 28v, 6a hyper speed control synchronous dc/dc buck regulator 1 note: 16. micrel, inc.: www.micrel.com .
micrel, inc. mic26603 - za may 2 1 , 20 13 26 revision 1.0 pcb layout recommendations mic26603 - za evaluation board top layer mic26603 - za evaluatio n board mid - layer 1 (ground plane)
micrel, inc. mic26603 - za may 2 1 , 20 13 27 revision 1.0 pcb layout recommendations (continued) mic26603 - za evaluation board mid - layer 2 mic26603 - za evaluation board bottom layer
micrel, inc. mic26603 - za may 2 1 , 20 13 28 revision 1.0 package information and recommended land pattern ( 17) 28- pin 5mm x 6mm qfn (jl) note: 17. package information is correct as of the publication date. for updates and most current information, go to www.micrel.com . 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 intende d 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 a ny 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 a nd/or use of micrel products including 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 support 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 sustain life, and whose failure to perform can be reasonably expected to result in a significant i njury to the user. a purchaser?s use or sale of micrel products for use in life support appliances, devices or systems is a purcha ser?s own risk and purchaser agrees to fully indemnify micrel for any damages resulting from such use or sale. ? 20 13 micrel, incorporated.

▲Up To Search▲

Price & Availability of MIC26603-ZAYJL

	To Download MIC26603-ZAYJL Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .