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november 2006 1 mic29310/29312 mic29310/29312 micrel general descriptionthe mic29310 and mic29312 are low cost versions of mic29300 family low-dropout (ldo) regulators. manufac- tured on micrels proprietary super beta pnp? process, the mic29310/2 is a 3a ldo regulator with very low-dropout voltage (600mv over the full load) and low ground current. along with a total accuracy of 2% (over temperature, line and load regulation) these regulators feature very fast tran- sient recovery from input voltage surges and output load current changes. the mic29310 is available in ? xed 3.3v and 5v outputs voltages; the mic29312 has an adjustable output which can be set by two external resistors to a voltage between 1.24v to 15v. in addition, all versions are fully protected against overcurrent faults, reversed input polarity, reversed lead insertion, and overtemperature operation. a ttl logic enable (en) pin is available in the mic29312 to shutdown the regulator. when not used, the device can be set to continuous operation by connecting en to the input (in). the mic29310/2 is available in the standard 3- and 5-pin to-220 and to-263 packages with an operating junction temperature range of 0c to +125c. features low cost versions of mic29300 family fast transient response 3a current over full temperature range 600mv dropout voltage at full load low ground current accurate 1% guaranteed tolerance zero current shutdown mode (mic29312) fixed voltage and adjustable versions applications processor peripheral and i/o supplies pc add-in cards high-ef ? ciency green computer systems high-ef ? ciency linear power supplies high-ef ? ciency switching supply post regulator battery-powered equipment mic29310/29312 3a fast-response ldo regulator typical application in out gnd v in v out mic29310-x.x fixed regulator con ? guration mic29312 out adj r1* v out * for best performance, total series resistance (r1 + r2) should be small enough to passthe minimum regulator load current of 10ma. r2* en gnd v in in onoff v out = 1.240 r1 r2 + 1 adjustable regulator con ? guration for applications requiring even lower dropout voltage, input voltage greater than 16v, or an error ? ag, see the mic29300/29301/29302/ 29303. micrel, inc. 2180 fortune drive san jose, ca 95131 usa tel + 1 (408) 944-0800 fax + 1 (408) 474-1000 http://www.micrel.com downloaded from: http:///
mic29310/29312 micrel mic29310/29312 2 november 2006 pin description pin number pin number pin name pin function mic29310 mic29312 1 en enable (input): active-high, logic-level enable/shutdown control. 1 2 in unregulated input: +16v maximum supply. 2, tab 3, tab gnd ground: ground pin and tab are internally connected. 3 4 out regulator output 5 adj ouput voltage adjust: 1.24v feedback from external resistive divider. pin con ? guration tab 3out 2gnd 1in mic29310-x.xbt/wt to-220-3 (t) tab 5adj 4out 3gnd 2in 1en mic29312-x.xbt/wt to-220-5 (t) tab 3out 2gnd 1in mic29310-x.xbu/wu to-263-3 (u) tab 5adj 4out 3gnd 2in 1en mic29312-x.xbu/wu to-263-5 (u) absolute maximum ratings (note 1) input voltage (v in ) ..........................................C20v to +20v power dissipation (p d ) ............................. internally limited storage temperature range (t s ) ............. C65c to +150c lead temperature (soldering, 5 sec.) ........................ 260c esd, note 3 operating ratings (note 2) input voltage (v in ) ........................................ +2.3v to +16v junction temperature (t j ) ............................ 0c to +125c package thermal resistance to-263 ( jc ) ......................................................... 2c/w to-220 ( jc ) ......................................................... 2c/w to-220 ( ja ) ....................................................... 55c/w ordering information part number voltage junction temperature range package standard rohs compliant (1) mic29310-3.3bt mic29310-3.3wt 3.3v 0c to +125c to-220 mic29310-3.3bu mic29310-3.3wu 3.3v 0c to +125c to-263 mic29310-5.0bt mic29310-5.0wt 5.0v 0c to +125c to-220 mic29310-5.0bu mic29310-5.0wu 5.0v 0c to +125c to-263 mic29312bt mic29312wt adj. 0c to +125c to-220 mic29312bu mic29312wu adj. 0c to +125c to-263 note: 1. rohs compliant with high-melting solder exemption. downloaded from: http:///
november 2006 3 mic29310/29312 mic29310/29312 micrel electrical characteristics (note 11) t j = 25c, bold values indicate 0c t j +125c; unless noted parameter condition min typ max units output voltage 10ma i o i fl , (v out + 1v) v in 8v, note 4 C2 2 % line regulation i o = 10ma, (v out + 1v) v in 16v 0.06 0.5 % load regulation v in = v out + 1v, 10ma i out i full load , notes 4, 8 0.2 1 % v o / t output voltage temperature coef ? cient, note 8 20 100 ppm/c dropout voltage v out = C1%, note 5 i o = 100ma 80 200 mv i o = 750ma 220 mv i o = 1.5a 330 mv i o = 3a 600 1000 mv ground current i o = 750ma, v in = v out + 1v 5 20 ma i o = 1.5a 15 ma i o = 3a 60 150 ma i gnddo ground pin v in = 0.5v less than speci ? ed v out . i out = 10ma 2 3 ma current at dropout current limit v out = 0v, note 6 3.0 3.8 a minimum load current 7 10 ma e n , output noise voltage c l = 10f 400 v rms (10hz to 100khz) i l = 100ma c l = 33f 260 v rms reference (mic29312 only) reference voltage 10ma i o i fl , v out + 1v v in 8v, note 4 1.215 1.265 v max adjust pin bias current 40 80 na 120 na reference voltage note 9 20 ppm/c temperature coef ? cient adjust pin bias current 0.1 na/c temperature coef ? cient enable input (mic29312 only) input logic voltage low (off) 0.8 v high (on) 2.4 v enable pin input current v en = v in 15 30 a 75 a v en = 0.8v C 2 a 4 a regulator output note 10 10 a current in shutdown 20 a note 1. exceeding the absolute maximum rating may damage the device. note 2. the device is not guaranteed to function outside its operating rating. note 3. devices are esd sensitive. handling precautions recommended. note 4: full load current is de ? ned as 3a for the mic29310/29312. for testing, v out is programmed to 5v. note 5: dropout voltage is de ? ned as the input-to-output differential when the output voltage drops to 99% of its nominal value with v out + 1v applied to v in . note 6: for this test, v in is the larger of 8v or v out + 3v. note 7: ground pin current is the regulator quiescent current. the total current drawn from the source is the sum of the load current plus the ground pin current. note 8: output voltage temperature coef ? cient is de ? ned as the worst case voltage change divided by the total temperature range. note 9: v ref v out (v in C 1v), 2.4v v in 16v, 10ma < i l i fl , t j t j(max). note 10: v en 0.8v and v in 8v, v out = 0. note 11: speci ? cation for packaged product only. downloaded from: http:///
mic29310/29312 micrel mic29310/29312 4 november 2006 block diagram on/off reference bias feed- back gnd 16v outadj* *en in o.v. i limit thermal shut-down * mic29312 only. mic29310/29312 downloaded from: http:///
november 2006 5 mic29310/29312 mic29310/29312 micrel 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0123 dropout voltage (v) output current (a) mic2931x dropout voltage vs. output current 0 0.2 0.4 0.6 0.8 1 -60 -30 0 30 60 90 120 150 dropout voltage (mv) temperature ( c) mic2931x dropout voltage vs. temperature i load = 3a 0.0 1.0 2.0 3.0 4.0 5.0 0246 output voltage (v) input voltage (v) mic29310-3.3 dropout characteristics i load = 3a i load = 10ma typical characteristics 6.525v4.525v 3.525v +20mv C20mv output voltage input voltage mic29312 line transient response with 3a load, 100f output capacitance 200s/division i out = 3a c out = 100f 6.525v4.525v 3.525v +20mv C20mv output voltage input voltage mic29312 line transient response with 3a load, 10f output capacitance 200s/division i out = 3a c out =10f 0ma 200ma 3a 3.525v +20mv C20mv load current output voltage mic29312 load transient response (see test circuit schematic) 1ms/division v in = v out + 1v mic29312 en in out adj gnd 0.1f 93.1k1% 49.9k 1% v out 3.525v nominal 4 330f avx tpse337m006r0100 tantalum v out load (not shown): intel? power validato r mic29312 load transient response test circuit downloaded from: http:///
mic29310/29312 micrel mic29310/29312 6 november 2006 0 10 20 30 40 50 -60 -30 0 30 60 90 120 150 adjust pin current (na) temperature ( c) mic29312 adjust pin current vs. temperature i load = 10ma 0.0 1.0 2.0 3.0 4.0 5.0 6.0 -60 -30 0 30 60 90 120 150 ground current (ma) temperature ( c) mic2931x ground current vs. temperature i out = 750ma 0 5 10 15 20 -60 -30 0 30 60 90 120 150 ground current (ma) temperature ( c) mic2931x ground current vs. temperature i out = 1.5a 0 20 40 60 80 100 -60 -30 0 30 60 90 120 150 ground current (ma) temperature ( c) mic2931x ground current vs. temperature i out = 3a 0 10 20 30 40 50 60 0123 ground current (ma) output current (a) mic2931x ground current vs. output current 3.20 3.22 3.24 3.26 3.28 3.30 3.32 3.34 3.36 3.38 3.40 -60 -30 0 30 60 90 120 150 output voltage (v) temperature ( c) mic29310-3.3 output voltage vs. temperature 3 devices 0 1 2 3 4 5 6 -60 -30 0 30 60 90 120 150 current (a) temperature ( c) mic2931x short circuit current vs. temperature v out = 0v 0 5 10 15 20 25 30 35 40 -60 -30 0 30 60 90 120 150 enable current ( a) temperature ( c) mic29312 enable current vs. temperaure v en = 5v v en = 2v 0.001 0.01 0.1 1 10 10x10 0 100x10 0 1x10 3 10x10 3 100x10 3 1x10 6 output impedance ( ? ) frequency (hz) mic2931x output impedance vs. frequency 0.0 0.5 1.0 1.5 2.0 024681 0 ground current (ma) input voltage (v) mic2931x ground current vs. input voltage i out = 10ma 0 50 100 150 200 024681 0 ground current (ma) input voltage (v) mic2931x ground current vs. input voltage i out = 3a -0.5 0.0 0.5 1.0 1.5 2.0 -20 -10 0 10 20 ground current (ma) input voltage (v) mic2931x ground current vs. input voltage r load = 100 ? v out = 3.3v downloaded from: http:///
november 2006 7 mic29310/29312 mic29310/29312 micrel applications informationthe mic29310 and mic29312 are high performance low-drop- out voltage regulators suitable for all moderate to high-current voltage regulator applications. their 600mv of dropout voltage at full load make them especially valuable in battery powered systems and as high ef ? ciency noise ? lters in post-regulator applications. unlike older npn-pass transistor designs, where the minimum dropout voltage is limited by the base-emitter voltage drop and collector-emitter saturation voltage, dropout performance of the pnp output of these devices is limited merely by the low v ce saturation voltage. a trade-off for the low dropout voltage is a varying base drive requirement. but micrels super ?eta pnp? process reduces this drive requirement to merely 2% to 5% of the load current. mic29310/312 regulators are fully protected from damage due to fault conditions. current limiting is provided. this limiting is linear; output current under overload conditions is constant. thermal shutdown disables the device when the die temperature exceeds the maximum safe operating temperature. transient protection allows device (and load) survival even when the input voltage spike above and below nominal. the output structure of these regulators allows volt- ages in excess of the desired output voltage to be applied without reverse current ? ow. the mic29312 version offers a logic level on/off control: when disabled, the devices draw nearly zero current. an additional feature of this regulator family is a common pinout: a designs current requirement may change up or down yet use the same board layout, as all of micrels high-current super ?eta pnp? regulators have identical pinouts. in out gnd v out figure 3. the mic29310 regulator requires only two capacitors for operation. thermal design linear regulators are simple to use. the most complicated design parameters to consider are thermal characteristics. thermal design requires the following application-speci ? c parameters: maximum ambient temperature, t a output current, i out output voltage, v out input voltage, v in first, we calculate the power dissipation of the regulator from these numbers and the device parameters from this datasheet. p d = i out (1.02v in C v out ) where the ground current is approximated by 2% of i out . then the heat sink thermal resistance is determined with this formula: t j max C t a sa = C ( jc + cs ) p d where t j max 125c and cs is between 0 and 2c/w. the heat sink may be signi ? cantly reduced in applications where the minimum input voltage is known and is large com-pared with the dropout voltage. use a series input resistor to drop excessive voltage and distribute the heat between this resistor and the regulator. the low dropout properties of micrel super ?eta pnp regulators allow very signi ? cant reductions in regulator power dissipation and the associated heat sink without compromising performance. when this technique is employed, a capacitor of at least 0.1f is needed directly between the input and regulator ground. please refer to application note 9 for further details and ex- amples on thermal design and heat sink speci ? cation. capacitor requirementsfor stability and minimum output noise, a capacitor on the regulator output is necessary. the value of this capacitor is dependent upon the output current; lower currents allow smaller capacitors. mic29310/2 regulators are stable with a minimum capacitor value of 10f at full load. this capacitor need not be an expensive low esr type: aluminum electrolytics are adequate. in fact, extremely low esr capacitors may contribute to instability. tantalum capaci- tors are recommended for systems where fast load transient response is important. where the regulator is powered from a source with a high ac impedance, a 0.1f capacitor connected between input and gnd is recommended. this capacitor should have good characteristics to above 250khz. transient response and 5v to 3.3v conversion the mic29310/2 have excellent response to variations in input voltage and load current. by virtue of their low dropout voltage, these devices do not saturate into dropout as readily as similar npn-based designs. a 3.3v output micrel ldo will maintain full speed and performance with an input supply as low as 4.2v, and will still provide some regulation with sup- plies down to 3.8v, unlike npn devices that require 5.1v or more for good performance and become nothing more than a resistor under 4.6v of input. micrels pnp regulators provide superior performance in 5v to 3.3v conversion applications than npn regulators, especially when all toler- ances are considered. minimum load current the mic29310/2 regulators are speci ? ed between ? nite loads. if the output current is too small, leakage currents dominate downloaded from: http:///
mic29310/29312 micrel mic29310/29312 8 november 2006 and the output voltage rises. a 10ma minimum load current is necessary for proper regulation. adjustable regulator design figure 4. adjustable regulator with resistors the adjustable regulator version, mic29312, allows program-ming the output voltage anywhere between 1.25v and the 15v maximum operating rating of the family. two resistors are used. resistors can be quite large, up to 1m , because of the very high input impedance and low bias current of the sense comparator. the resistor values are calculated by: v out r1 = r2 ( C C 1 ) 1.240where v o is the desired output voltage. figure 4 shows component de ? nition. applications with widely varying load currents may scale the resistors to draw the minimum load current required for proper operation (see the table below). enable input the mic29312 version features an enable (en) input that allows on/off control of the device. special design al- lows zero current drain when the device is disabledonly microamperes of leakage current ? ows. the en input has ttl/cmos compatible thresholds for simple interfacing with logic, or may be directly tied to v in . enabling the regulator requires approximately 20a of current into the en pin. voltage standard ( ) min. load ( ) r1 r2 r1 r2 2.85 100k 76.8k 162 124 2.9 100k 75.0k 165 124 3.0 100k 69.8k 174 124 3.1 100k 66.5k 187 124 3.15 100k 64.9k 191 124 3.3 100k 60.4k 205 124 3.45 100k 56.2k 221 124 3.6 100k 52.3k 237 124 3.8 100k 48.7k 255 124 4.0 100k 45.3k 274 124 4.1 100k 43.2k 287 124 resistor value table for the mic29312 adjustable regulator note: this regulator has a minimum load requirement. standard values assume the load meets this requirement. minimum load values are calculated to draw 10ma and allow regulation with an open load (the minimum current drawn from the load may be zero). downloaded from: http:///
november 2006 9 mic29310/29312 mic29310/29312 micrel package information 3-pin to-220 (t) 3-pin to-263 (u) downloaded from: http:///
mic29310/29312 micrel mic29310/29312 10 november 2006 5-pin to-220 (t) 5-pin to-263 (u) downloaded from: http:///
november 2006 11 mic29310/29312 mic29310/29312 micrel downloaded from: http:///
mic29310/29312 micrel mic29310/29312 12 november 2006 micrel, inc. 2180 fortune drive san jose, ca 95131 usa tel + 1 (408) 944-0800 fax + 1 (408) 474-1000 web http://www.micrel.com the information furnished by micrel in this data sheet is believed to be accurate and reliable. however, no responsibility is assumed by micrel for its use. micrel reserves the right to change circuitry and speci ? cations at any time without noti ? cation to the customer. 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 signi ? cant injury to the user. a purchasers use or sale of micrel products for use in life support appliances, devices or systems is at purchasers own risk and purchaser agrees to fully indemnify micrel for any damages resulting from such use or sale. ? 2005 micrel, incorporated. downloaded from: http:///

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