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mic1344 smart, 3 a, two - channel, power oring switch micrel inc. ? 2180 fortune drive ? san jose, ca 95131 ? usa ? tel +1 (408) 944 - 0800 ? fax + 1 (408) 474 - 1000 ? http://www.micrel.com april 24, 2015 revision 1.0 general description the mic1344 is an advanced two input, one output, hot swappable, power multiplexer. it has both automatic and manual input selection ( ena and enb) and four status outputs . in automatic mode, the mic1344 will automatically connect the hi gher of two input voltages (ina or inb), to the output (out). in manual mode, either of the two inputs can be routed to the output, or both power inputs can be turned off so that multiple mic1344?s can be used for more than two power inputs. the mic1344 ha s four digital open drain status outputs. the asel \ and bsel \ outputs indicate which input is selected . the staok and stbok outputs indicate the general health of the input channels. specifically, these outputs will be inactive (high) if the channel has su fficient input voltage, the channel current is within acceptable limits, the die temperature is not too hot, and the channel has no reverse current detected. the current limit for each input channel of the mic1344 can be individually set up to 3a, by two external current - limit set resistors (ilima and ilmib). the current flowing in each of the channels can be read by measuring the voltage at these resistors. datasheets and support documentation are available on micrel?s web site at: www.micrel.com . features ? two input, one output, power oring switch ? input voltage operating range: 2.8v to 5.5v ? automatic and manual input selection modes ? four digital and two analog status outputs ? current blocking: o utput - to - input and inpu t - to - input ? low on - resistance (70m ? typical) ? up to 3a current handling ? low standby channel current (11 a typical) ? separate current limiting and readback for each channel ? available in 12 - pin, 2 mm 2 mm , qfn (ftqfn) package ? thermal - shutdown protection ? ? 40c to 125c j unction temperature range applications ? two input to one output power selector ? multiple inputs to a single output power selector ? charger input power selector ? dual battery selector ? main and backup power selector ? usb power selector ? portable product s ? supercapacitor oring ? backup battery diode oring typical application
micrel, inc. mic1344 april 24, 2015 2 revision 1.0 ordering information part number marking output current junction temperature range package ( 1 , 2 ) MIC1344YFT 4n adjustable (3.0a maximum) ? 40c to +125c 12- pin 2mm 2mm ftqfn notes: 1. pin 1 indicator = ? 2. green rohs compliant package. lead finish is nipdau. mold compound is halogen free. pin configuration 12- pin 2mm 2mm f tqfn (ft) (top view) pin description pin number pin name pin function 1 inb supply voltage input b. t his input may be bypassed to gnd with > 0. 1f, x7r or similar, ceramic type capacitor. this input is hot swappable. 2 stbok open drain output, digital status monitor fo r supply voltage input b (inb). voltage will be low if a ny of the following conditions occur : ? inb is below the u vlo limit . ? the output current fr om inb is at its set current limit . ? the die temperature exceeds the overtemperature limit. ? reverse current dete cte d (v out > v inb +100mv ). ? prolonged h igh hysteresis mode engaged . 3 bsel \ open drain output . low if input b (inb) is providing power to the out pin . 4 ilimb a resistor from this pin to ground sets the current limit for inb. the current flowing into inb c an be monitored by the voltage on this pin. 5 enb the ena and enb digital inputs control which voltage input (ina or inb) is connected to the voltage out (out) pin. there is an internal 5 7 0k ? pull - down on this pin to ensure that automatic select mode is active when the logic that is driving the mic1344 is being powered up. table 1 shows how to control the power routing with the ena and enb inputs. 6 gnd ground.
micrel, inc. mic1344 april 24, 2015 3 revision 1.0 pin description (continued) pin number pin name pin function 7 ena the ena and enb digital inputs control which voltage input (ina or inb) is connected to the voltage out (out) pin. there is an internal 570k ? pull - down on this pin to ensur e that automatic select mode is active when the logic that is driving the mic1344 is being powered - up. table 1 shows how to control the power routing with the ena and enb inputs. 8 ilima a resistor from this pin t o ground sets the current limit for ina. the current flowing into ina can be monitored by the voltage on this pin. 9 asel \ open drain output . low if input a (ina) is providing power to the out pin. 10 staok open drain output, digital status monitor for s upply voltage input a (ina). voltage will be low if any of the following conditions occur: ? ina is below the uvlo limit. ? the output current from ina is at its set current limit. ? the die temperature exceeds the overtemperature limit. ? reverse current detecte d (v out > v ina +100mv). ? prolonged high hysteresis mode engaged. 11 ina supply voltage input a. t his input may be bypassed to gnd with > 0. 1f, x7r or similar, ceramic type capacitor. this input is hot swappable. 12 out voltage output . this is the power out put. bypass this pin to ground with a capacitor suitable to provide adequate power during the switchover time of the mic1344. this capacitor should be a minimum of 10f, x7r or similar temperature stability, ceramic capacitor. ep epad internally connec ted to electrical ground ( gnd) pin . connect to as large a pcb area as practical to dissipate heat from the mic1344.
micrel, inc. mic1344 april 24, 2015 4 revision 1.0 absolute maximum ratings ( 3 ) ina, inb, out, ena, enb ........................... ? 0.3v to +6.0v asel \ , bsel \ , staok, stbok .................. ? 0.3v to +6.0v ilima ..................................................... ? 0.3v to v ina +0.3v ilimb ..................................................... ? 0.3v to v inb +0.3v power dissipation (p d ) ........................... internally limite d (6) lead temperature (soldering, 10 s ) ............................ 260c junction temperature (t j ) ........................ ? 40c to +125c storage temperatu re (t s ) ......................... ? 65c to +150c esd rating ................................................................. note 7 operating r atings ( 4 ) ina, in b (5) .................................................... + 2.8v to +5.5v out, ena, enb ................................................ 0v to +5.5v asel \ , bsel \ , staok, stbok ....................... 0v to +5.5v ilima ..................................................................... 0v to v ina ilimb ..................................................................... 0v to v inb junction temperature (t j ) ........................ ? 40c to +125c junction thermal resistance 12- pin 2mm 2mm ft qfn : ja ............................................................. 77.9c/w jc ............................................................. 11.9c/w electrical characteristics v ina or v inb = 5v; i out = 100ma; c ina = c inb = 1f, c out = 10f, t j = + 25c, bold values indicate junction temperature ? 40c to +125c, unless noted. parameter condition min . typ . max . units supply current both inputs disabled, i out = 0a . per channel. 11 15 a one of the inputs enabled, i out = 0a . 300 350 ina and inb rising uvlo voltage 2.2 2.35 2.5 v uvlo hysteresis 0.1 v in a or in b switch resistance i out = 500 ma. 70 200 m ? v ina or v inb = 2.8 v, i out = 500ma 120 2 2 0 m ? output -to - input leakage current leakage current of out t o ina or inb when the corresponding input channel is turned off . 1 10 a input -to - input leakage current leakage current of ina to inb, or inb to ina . 1 10 a ina -to -in b or inb -to - ina switchover comparator hysterisis voltage 300 mv ilima or ilimb output current accuracy (in = 2.8v) r ilima , r ilimb = 931 ? 2. 58 2.85 3.15 a r ilima , r ilimb = 10k ? 0.2 5 0.28 0.31 ilima or ilimb output current accuracy (in = 5.5v) r ilima , r ilimb = 931 ? 2.40 2.7 3.00 a r ilima , r ilimb = 10k ? 0.20 0.25 0.30 ina or inb reverse voltage shutdown threshold v out = 2.6v to v in a = 2.5v (with ina selected) or v out = 2.6v to v inb = 2.5v (with inb selected) 100 mv ina or inb reverse voltage shutdown hysteresis v out falling 50 mv notes: 3. exceeding the absolute maximum ratings may damage the device. 4. the device is not guarantee d to function outside its operating ratings. 5. ina and inb can be taken to 0v; h owever the minimum operating voltage is 2.8v. 6. the maximum allowable power dissipation of any t a (ambient temperature) is p d(max) = (t j(max) ? ta) / ja . exceeding the maximum allowable power dissipation will result in excessive die temperature, and the mic1344 will go into thermal shutdown . 7. devices are esd sensitive. handling precautions recommended. human body model (hbm) is 1.5k in series with 100pf. machine model (mm), is 200pf, per jesd 22 - a115.
micrel, inc. mic1344 april 24, 2015 5 revision 1.0 electrical characteristics (continued) v ina or v inb = 5v; i out = 100ma; c ina = c inb = 1f, c out = 10f, t j = + 25c, bold values indicate junction temperature ? 40c to +125c, unless noted. par ameter condition min . typ . max . units ilima or ilimb current - limit onset threshold voltag e ( 8 ) r i lima , r i limb = 10k ? 1.1 0 1.20 1. 30 v v ilima or v ilimb for low - current v ina or v inb = 3.5v, i out = 20ma 15 100 1 85 mv ina or inb high - load shutdown response tim e ( 9 ) i out = 0ma to r out = 0.1 ? (turn off transition time, no load to high - current load) 1.5 s automatic mode switchover delay time ( 10 ) automatic mode, v ina + 300mv v inb or v in b + 300mv v in a 5 10 s ina -to - inb manual mode switchover delay t ime ( 11) time from inb selected to v out = 90% of v inb voltage v ina = 0v, v inb = 5v 350 700 s inb -to - ina manual mode switchover delay tim e ( 11) time from ina selected to v out = 90% of v ina voltage v ina = 5v, v inb = 0v 350 700 s switch off delay ti me ( 12) automatic mode, ina or inb selected to no input selected. r out = 10 ? . no c out 0.5 s initial power - up d elay ( 13) automatic mode, ina or inb selected. r out = 10 ? , v ina or v inb transitions from 0 v to 5v 0.3 1 ms ena or enb input resistance 570 k ? 5v ena or enb logic level low voltage voltage falling. v ina or v inb = 5v. 1.20 1.0 5 v 3v ena or enb logic level low voltage voltage falling. v ina or v inb = 3v. 0.8 0.60 v 5v ena or enb threshold hysteresis v ina or v inb = 5v. 300 mv staok or stbok active, output voltage i staok or i stbok = 10ma 0.15 0.3 v staok or stbok inactive, leakage current v staok or v stbok = 5v (leakage current to gnd) 1 a asel \ or bsel \ active, output voltage i asel \ or i bsel \ = 10ma 0.15 0.3 v asel \ or bsel \ inactive, leakage current v asel \ or v bsel \ = 5v (leakage current to gnd) 1 a overtemperature shutdown temperature threshold junction temperature increasing 150 c overtemperature shutdown hysteresis 2 0 c notes: 8. the current - limit threshold onse t voltage is the voltage on ilim (a or b) that corresponds to the onset of the output current regulation for the corresponding input channel. 9. the time it takes for the output current on either ina or inb to go from 0ma (no load) to 20% over the steady state maximum current - limit value, w hen a load of 0.1 ? is applied between the out pin and gnd . 10. this is the time that the mic1344 takes to switch between one of the two input voltage s when it is in automatic mode. this is the time from when one of the input voltages goes above the other by 300mv, to the time when the output voltage reaches 90% of its final value. 11. this is the time it takes to switch from one input (ina or inb) to the other (inb or ina), when in manual mode. this is the t ime from the enx transition, to when the output voltage reaches 90% of its final value. (x can be either a, or b). 12. this is the time from the ena = 0, enb = 1 transition, to when the output voltage reaches 10% of its initial value. 13. this is the time between when the mic1344 is powered up (10% of the v ina or v inb voltage ramp - up), to the time when the out voltage stabilizes to within 90% of its final value.
micrel, inc. mic1344 april 24, 2015 6 revision 1.0 typical characteristics 0 50 100 150 200 250 300 0 1 2 3 4 5 i supply (a) in (v) supply current vs. input voltage no input selected ina or inb selected 0 50 100 150 200 250 300 -50 -25 0 25 50 75 100 125 i supply (a) temperature ( c) supply current vs. temperature ina or inb selected no input selected vina or vinb = 5v 40 50 60 70 80 90 100 110 120 130 140 2.5 3.0 3.5 4.0 4.5 5.0 switch on - resistance (m ? 40 50 60 70 80 90 100 -50 -25 0 25 50 75 100 125 switch - on resistance (m ? channel a or channel b v ina or v inb = 5v 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20 -50 -25 0 25 50 75 100 125 leakage current (a) temperature ( c) v ina to v inb or v inb to v ina leakage vs. temperature 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 -50 -25 0 25 50 75 100 125 leakage current (a) temperature ( c) output to vina or vinb leakage vs. temperature 0.4 0.6 0.8 1 1.2 1.4 1.6 2.5 3.0 3.5 4.0 4.5 5.0 en on voltage (v) in (v) en on voltage vs. in voltage 0 0.5 1 1.5 2 2.5 3 0 2 4 6 8 10 current limit (a) ilim resistance (k ? 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 0 50 100 150 200 250 300 v ilim (v) load current (ma) v ilim vs. load current vin = 3.3v r ilim = 10k ?
micrel, inc. mic1344 april 24, 2015 7 revision 1.0 typical characteristics (continued) 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 0.0 0.5 1.0 1.5 2.0 2.5 3.0 v ilim (v) load current (a) v ilim vs. load current vin = 3.3v r ilim = 1k ? 0 0.5 1 1.5 2 2.5 3 -50 -25 0 25 50 75 100 125 current limit (a) temperature ( c) current limit vs. temperature r ilim = 931 ? r ilim = 10k ? 0 0.5 1 1.5 2 2.5 3 2.5 3.0 3.5 4.0 4.5 5.0 current limit (a) in (v) current limit vs. in r ilim = 931 ? r ilim = 10k ? 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 0.1 1.0 10.0 100.0 output voltage droop (v) cl load capacitance (f) output switchover voltage droop vs. load capacitance automatic mode v ina = 4.5v v inb = 4v to 5.5v r l = 10 ?
micrel, inc. mic1344 april 24, 2015 8 revision 1.0 functional characteristics
micrel, inc. mic1344 april 24, 2015 9 revision 1.0 sys tem connection diagram
micrel, inc. mic1344 april 24, 2015 10 revision 1.0 functional block diagram
micrel, inc. mic1344 april 24, 2015 11 revision 1.0 application information operation overview the mic1344 is an advanced two input, one output, hot swappable, power multiplexer. it has both automatic and manual input selection ( ena and enb ), and four status outputs (staok, stbok, asel \ , and bsel \ ) . the following sections give a more detailed explanation regarding the application of this part. channel selection table 1 shows how the mic1344 will rout e the input power as controlled by the ena and enb input pins. if a transition occurs on either ena or enb, the part will wait an additional 10 s before implementing the new code. this delay allows the two enable pins to be slightly out of sync and not cau se a momentary selection of an unwanted mode. table 1 . ena and enb input power selection ena enb power input selected 0 0 automatic mode. t he h igher voltage on either ina or inb automatically selected if > v uvlo . 0 1 no input sele cted ( can be used for cascading other mic1344 power inputs). 1 0 ina power input selected if v ina > v uvlo . 1 1 inb power input selected if v inb > v uvlo . if the value s of ena and enb are logic low when the mic1344 powers up, the mic1344 will automatical ly select the power input with the higher voltage and route it t o the output. this is the normal power - up se quence for the mic1344. if both inputs are below the under voltage lockout voltage, then the output will be high impedance. if the s elect inputs are driven by external logic that is powered by the mic1344, the n those logic outputs can either be low or open circuit , and the mic1344 will automatically bias up the logic when it is powered up. b oth input power sources can be turned off by putting ena = 0, enb = 1 on the enable input pins. one operating scenario to be aware of is that if the l ogic 1 on the enb input is generated by a device powered via the mic1344 output, the input of the m i c1344 will be set at en a = 0 and en b = 0 when the power is turned of f. with en a = 0 and en b = 0, the part will automatically select the higher of the two input voltage s and turn back on again. the no input selected mode is typically used when more than two power sou rces are required (cascading multiple mic1344 s) and both i nputs must be turned off so that the third or fourth power input can be turned on. when no input is selected, the mic1344 will block current flow from the output (out), to either input (ina or inb), as well as from either input (ina or inb) to the outp ut (out). for applications that require changing between the a and b power input with only one control line, set ena = 1, and use the enb input to set whi ch of the two inputs is active. current limiting the current limits in the two inputs of the mic1344 c an be set independently . this allows mixing input sources that have different current capacity, like a main, and backup power supply. the current limit for ina is set by the il ima resistor to gnd , while the current limit for inb is set by the ilimb resisto r to gn d. a graph of the ilim resistance vs current limit can be found in the typical characteristics section of this datasheet. the ilim resistor value can be calculated by equation 1 : a 146 i 2485 r cl ilim ? = ? ) r ilim should be set between 11k ? and 800 ? . setting resistor r ilim equal to zero is not recommended as it will disable current limiting . during a current limit event, if the mic1344 is in automatic mode, then the automatic switching will be blocked because switching over to the other channel will load it, taking its voltage low, and unloading the other channel taking its voltage high. blocking the automatic switchover mode pr events the possible oscillation of the mic1344 switching between the two inputs, as they become loaded by the heavy load condition. switching the channels manually is allowed. current flowing in the ina or inb inputs can be measured by the voltage on the corresponding ilim pin. these pins can be connected to the input of an analog - to - digital converter (adc), to read the current digitally. when the voltage at the ilim pins reaches 1.20v (typical), the mic1344 will regulate the input curr ent on the correspon ding input to the maximum value and make the correspondi ng status pin (staok or stbok) go active (low). the mic1344 will hold this maximum value indefinitely or until the part overheats. should the part
micrel, inc. mic1344 april 24, 2015 12 revision 1.0 overheat, it will turn off both input channels and bo th status pins (staok and stbok) will go active (low). the voltage on the ilim pin can be calculated by equation 2: ) k 170 r ( ) 1 . 82 r i ( v ilim ilim out ilim ? + ? = ? ) the curren t limit circuit is filtered to avoid erroneous flagging of the staok or stbok pins from output current spikes . the current limit must be engaged for at least greater than 50% of the time over a prolonged period of time , or constantly for at least 5ms befo re the flag is driven low. the flag will then be held low for at least 5ms after the current limit event is over, or until the current limit is engaged less than 50% of the time over a prolonged period of time . if the mic1344 changes between input channel s that have different current limits, the load may need to be changed to accommodate the different current limit value. if there is a system controller, it would be notified of the selected ina or inb input channel through the asel \ and bsel \ outputs. one example is a situation where a microprocess or runs two different programs or load sets, depending on whether the power is main (normal input power), or backup (battery, etc . ). digital status output pins the mic1344 features four digital channel status o utp ut pins, specifically staok, asel \ , stbok, and bsel \ . the power for the status pins is acquired fr om the corresponding input, i.e., the control power for staok and asel \ is acquired from ina with inb providing the control power for s tbok and bsel \ . the dig i tal status pins are open drain and require pull - up resistors to function . it is recom mended that the open - drain pull - up resistors be connected to the corresponding input power to ensure the indicators will be accura te below the uvlo v oltage . s taok and ase l \ should be pulled - up to ina with stbok and bsel \ being pulled - up to inb. if there is no voltage at ina, the staok output will be high impedance. if the pull - up resistor on staok is connected to v ina , then the staok will indicate the status of the input v oltage correctly (see figure 1 ). figure 1 . staok correctly flags for low input voltage when staok?s pull - up resistor is connected to ina if the pull - up is connected to another voltage and ina is below the nmos threshold, then the staok can falsely indicate that the input voltage is acceptable . this occurs due to the ina monitoring circuit requiring enough vo ltage to turn on the staok open - drain output transistor. this is also true for the inb and corresponding stbok status indicator and the asel \ and bsel \ outputs (see figure 2 ). figure 2 . staok incorrectly flags for low input voltage when staok?s pull - up resistors is connected to external 5v supply
micrel, inc. mic1344 april 24, 2015 13 revision 1.0 the asel \ and bsel \ status pins indicate which channel is selected and connected to the output . if asel \ is activ e (low), then ina is selected and i f bsel \ is active (low), then inb is selected. if both ase l \ and bsel \ are inactive (open - drain high), then neither of the two inputs is selected. this can occur if both ina and in b input voltages are below the u nder v oltage lock out (uvlo) voltage, or both i nputs have been manually turned - off (ena = 0, enb = 1). if high - value p ull - up resistors are used (>100k ? ), then minimal current will be inject ed into the digital input pins , allowing them to stay at a digital low for a lower input voltage below the uvlo voltage . e ach digital status output pin is capable of sinking 10ma, wh ich is sufficient current to dr ive leds, optocouplers, etc. passing the sta tus of the mic1344 through opto couplers allows communicating the power status across the isolation barrier of power systems. under voltage lockout both ina and inb have separate uvl o detection circuits. the uvlo status of ina is reflected on the staok status pin. likewise, the uvlo status of inb is reflected on the stbok status pin. this feature can be used to monitor the incoming voltage of the unselected input channel. if the selec ted in pin is below the uvlo voltage, then the channel will be turned off, and only reverse leakage current can flow. standard hysteresis mode in automatic mode, the voltage of the inactive input must be raised above the voltage of the active input by 30 0mv , in order for the mic1344 to switch to the inactive input. high hysteresis mode if four transitions between input channels occur within 8ms (ina inb ina inb) while the part is in automatic mode, then the 300mv switchover hysteresis will increas e to 600mv. this is the high hysteresis mode. in the high hysteresis mode the part can only switch between channels once per millisecond. the higher hysteresis and the forced delay helps prevent the part from chattering between inputs. i n the high hystere sis mode , i f there are four additional transitions in the next 8ms , then the status pin for the selected channel will go low ( staok if vina selected and stbok if vinb is selected). the part will exit the high hysteresis mode if there are fewer than four transitions in a subsequent 8ms period , or if a manual mode is selected. hot swappable inputs the power to ina and/or inb can be conne cted to input power and turned on or off without consequence to the other input power supply, as long as the minimum and maximum input voltage does not exceed the ratings of the mic1344. if the mic1344 is set to automatic mode (ena = 0, enb = 0), and power is applied to one of the channels, the mic1344 will wait until the input voltage is above the uvlo threshold, then it w ill wait the initial power up delay per iod , giving time for the input voltage to stabilize , and then connect the selected input to the out pin. refer to the ? current limiting ? sub - s ection for details of what occurs if the ina or inb input channels current limit. cascading more t han two input power sources on the mic1344, both inputs can be turned off using the ena = 0, enb = 1, no input selected mode. this mode is used when more than two power inputs are used. if t here is an input voltage at either ina or inb, the corresponding digital output status pins will stay active. this allows detection of the presence of an input voltage through the corresponding staok or stbok pins, even if the channel is not selected. reve rse voltage and on - channel voltage detection if one of the channels of the mic1344 is turned off, current is blocked from flowing from the out pin to the unselected in pin. for example; if ina is at 5v, and ina is selected, only a very small leakage curren t (<10a maximum) will flow between out, and the unselected inb. if a channel is turned on and the out voltage exceeds the corresponding in voltage, then reverse current may flow to the input. if the voltage at the out pin exceeds the voltage at the correspondingly selected in pin, then the channel will be turned off and the corresponding staok or stbok pin will go active ( low). for example, i f ina is selected and out exceeds ina by 100mv, then channel a will be turned off and staok will go acti ve, indicating that a fault has occurred. the same sequence occurs if c hannel b is selected and out exceeds inb by 100mv. once the differential between out and the selected in drops to 50mv, the selected channel will automatically turn back on. output c apacitor the output (out) requires sufficient capacitance that when the mic1344 switches between inputs (ina or inb), that the output voltage does not unacceptably droop (go low). the cause of the output voltage drooping is that the mic1344 switches ?break before make?, which will momentarily disconnect both inputs from the output. the switchover delay is specified in the electrical characteristics . a minimum of a 10f ceramic chip capacitor is recommended on the ou tput of the mic1344.
micrel, inc. mic1344 april 24, 2015 14 revision 1.0 overtemperature shutdown there is one die temperature monitor for both channels of the mic1344. if one of the two input channels causes an overtemperature condition, both channels will be shut down, and both the staok, stbok outputs w ill be active (low impedance, logic low), indicating that a fault has occurred. if the overtemperature condition is created by one of the ina or inb channels being in an overcurrent condition, then this condition can be determined by reading the voltage on the ilima or ilimb pins after the part cools down and the output recovers. pcb layout recommendations the mic1344 c omes in an ultra - small small 2mm 2mm package. the part has to have sufficient pcb area, and/or air flow so that it will not overheat. given a 3a load current, a nominal on - channel resistance of 7 0m?, a junction to ambient thermal resistance of 77.9c/w (depends on pcb area and air flow), and an ambient temperature of 76 c, the mic1344 die temperature will operate at the 125c limit. the mic1344 evaluation kit manual has more specifics on a recomme nded pcb layout for the mic1344.
micrel, inc. mic1344 april 24, 2015 15 revision 1.0 package information and recommended landing pattern ( 14) 12- pin 2mm 2mm ftqfn ( ft ) note: 14. package information is correct as of the publication date. for up dates and most current information, go to www.micrel.com .
micrel, inc. mic1344 april 24, 2015 16 revision 1.0 package information and recommended landing pattern ( 14) (continued) 12- pin 2 mm 2mm ftqfn ( ft )
micrel, inc. mic1344 april 24, 2015 17 revision 1.0 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, inc. is a leading global manufacturer of ic solutions for the worldwide high performance linear and power, lan, and t iming & communications markets. the company?s products include advanced mixed - signal, analog & power semiconductors; high - performance communication, clock management, mems - based clock oscillators & crystal - less clock generators, ethernet switches, and physical layer transceiver ics. company customers include leading manufacturers of enterprise, consumer, industrial, mobile, telecommunications, automotive, and computer products. corporation headquarters and state - of - the - art wafer fabrication facilities are located in san jose, ca, with regional sales and support offi ces and advanced technology design centers situated throughout the americas, europe, and asia. additionally, the company maintains an extensive network of distributors and reps worldwide. micrel makes no representations or warranties with respect to the accuracy or completeness of the inf ormation furnished in this data sheet. this information is not intended as a warranty and micrel does not assume responsibility for its use. micrel reserves the right to change circuitry, specifications and descriptions a t any time without notice. no license, whether express, implied, arising by estoppel or otherwise, to any intellectual property rights is granted by this document. e xcept as provided in micrel?s terms and conditions of sale for such products, micrel assum es no liability whatsoever, and micrel disclaims any express or implied warranty relating to the sale and/or use of micrel products including liability or warranties relating to fitness for a particul ar 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 mal function 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 expecte d to result in a significant injury to the user. a purchaser?s use or sale of micrel products for use in life support appliances, devices or systems is a purchaser?s own risk a nd purchaser agrees to fully indemnify micrel for any damages resulting from suc h use or sale. ? 20 15 micrel, incorporated.

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