5a low-voltage low-dropout regulator lm39500/39501/39502 features 5.0a minimum guaranteed output current 400mv typical dropout voltage ideal for 3.0v to 2.5v conversio n ideal for 2.5v to 1.8v or 1.5v conversio n 1% initial accuracy low ground current current limiting and thermal shutdown reversed-battery protection reversed-leakage protection fast transient response ttl/cmos compatible enable pin => lm39501 error flag output - lm39501 only ceramic capacitor stable(see application information) adjustable version - lm39502 only moisture sensitivity level 3 application s low-voltage digatal ics ldo linear regulator for pc add-in cards high-efficiency linear power supplies multimedia and pc processor supplies smps post regulator low-voltage microcontrollers strong arm? processor supply ordering information description the lm39500, lm39501 and lm39502 is a 5a low drop ? out linear voltage regulator that provides a low-voltage, high-current output with a minimum of external components. utilizing super beta pnp pass element. the lm39500 offers extremely low dropout (typically 400mv at 5a) and low ground current (typically 70ma at 5a). the lm39500/1/2 is ideal for pc add-in cards that need to conv ert from standard 5v or 3.3v, down to new, lower core voltages. a guaranteed maximum dropout voltage of 500mv over all operating allows the lm39500/1/2 to provide lm39500/1/2 to 2.5v from a supply as low as 3v. the lm 39500 also has fast transient response, for heavy switching applications. the device requires only 47f of output capacitance to maintain stability and achieve fast transient response. the lm39500/1/2 is fully protected with overcurrent limiting, thermal shutdown, reversed-battery and reversed-lead in-sertion protection. the lm39501 offers a ttl-logic-compat-ible enable pin and an er ror flag that indicates undervoltage and overcurrent conditions. the lm39500/1/2 comes in the to-220 and to-263 packages and is an ideal upgrade to older,npn-based linear voltage regulators. the lm39502 is adjustable version. 2008 - ver 1.0 htc pin description enable (input) in cmos-compatible control input. logic high = enable, logic gnd flg ground pin and tab are internally connected. lm39500-x.x adjustment input: feedback input. package lm39502-adj to-263 lm39501-x.x ? 1 ? lm39502r-adj logic low or open = shutdown supply (input): +16v maximum supply flag (output): open-collector error flag output. lm39501r-x.x to-263 lm39501-x.x regulator output adj out device marking to-263 lm39500-x.x LM39500R- x.x to-220 lm39502t-adj lm39502-adj lm39500t-x.x to-220 lm39501t-x.x to-220 * x.x = fixed vout = 1.5v, 1.8v, 2.5v, 3.3v, 5.0v to263-3l / to220-3l (39500-x.x fixed only) 1. in 2. gnd 3. out 1. en 2. in 3. gnd 4. out 5. flg or adj to263-5l / tl220-5l (39501-x.x & 39502 only) 1 3 1 5 1 3 1 5
5a low-voltage low-dropout regulator lm39500/39501/39502 t yp ical a pp lication circuit htc ? 2 ? absolute maximum ratings (note 1) supply voltage (vin) : C20v to +20v enable voltage (ven) : +20v storage temperature (ts) : C65c to +150c lead temperature (soldering, 5 sec) : 260c esd, note 3 operating ratings (note 2) supply voltage (vin) : +2.25v to +16v enable voltage (ven) : +16v maximum power dissipation (pd(max)) note 4 junction temperature (tj) : C40c to +125c package thermal resistance to-263( jc ) : 2c/w to-220( jc ) : 2c/w lm39500 lm39501 lm39502
5a low-voltage low-dropout regulator lm39500/39501/39502 htc ? 3 ? block dia g ram lm39501 fixed with flag and enable lm39502 adjustable lm39500 fixed (1.5v,1.8v,2.5v,3.3v,5.0v)
5a low-voltage low-dropout regulator lm39500/39501/39502 note 1. exceeding the absolute maximum ratings may damage the d evice. note 2. the device is not guaranteed to function outside its op erating rating. note 3. devices are esd sensitive. handling precautions recomm ended. note 4. p d(max) = (t j(max) C t a ) ja , where ja depends upon the printed circuit layout. see applications inf ormation. note 5.vout temperature coefficient is ?v out(worst case) (t j(max) C t j(min) ) where t j(max) is +125 and t j(min) is 0 note 6. v do = v in C v out when v out decreases to 98% of its nominal output voltage with v in = v out + 1v. note 7. i gnd is the quiescent current. iin = i gnd + i out . note 8. v en 0.8v, v in 8v, and v out = 0v note 9. for a 2.5v device, v in = 2.250v (device is in dropout). htc ? 4 ?
5a low-voltage low-dropout regulator lm39500/39501/39502 htc ? 5 ? application information the lm39500/1 is a high-performance low-dropout voltage regulat or suitable for moderate to high-current voltage regu-lator applications. its 400mv dropout voltage at full load makes it especially valuable in battery-powered systems and as a high-efficiency noise filter in post-regulator applications. unlike older npn-pass transistor designs, where the mini-mum dropout voltage is limited by the b ase-to-emitter voltage drop and collector-to- emitter saturation voltage, dropout per-formance of the pnp out put of these devices is limited only by the low v ce saturation voltage.a trade-off for the low dropout voltage is a varying base drive requirement. the lm39500/1/2 regulator is fully protected from damage due to fault conditions. current limiting is provided. this limiting is linear output current during overload conditions is constant. thermal shutdown disables the device when the die temperature exceeds the maximum safe operating tem-pera ture. transient protection allows device (and load) sur-vival even when the input voltage spikes above and be low nominal. the output structure of these regulators allows voltages in excess of the desired output voltage to be a pplied without reverse current flow. thermal design linear regulators are simple to use. the most complicated desig n parameters to consider are thermal characteristics.thermal design requires four application-specif ic param-eters: ?maximum ambient temperature (t a ) ?output current (i out ) ?output voltage (v out ) ?input voltage (v in ) ?ground current (i gnd ) calculate the power dissipation of the regulator from these num bers and the device parameters from this datasheet,where the ground current is taken from the data sheet . pd = (v in C v out ) i out + v in i gnd the heat sink thermal resistance is determined by: sa= (t jmax -t a )/p d -( jc + cs ) where tj (max) 125 and cs is between 0 and 2/w. the heat sink may be significantly reduced in applications wher e the minimum input voltage is known and is large compared 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 proper ties of taejin regulators allow signifi-cant reductions in regulator power dissipation and the asso-ciated heat sink wi thout compromising performance. when this technique is employed, a capacitor of at least 1.0f is needed d irectly between the input and regulator ground.refer to application note 9 for further details and examples on therm al design and heat sink specification. output capacitor the lm39500/1/2 requires an output capacitor to maintain stabil ity and improve transient response. proper capacitor selection is important to ensure proper operation. the lm39500/ 1/2 output capacitor selection is dependent upon the esr (equivalent series resistance) of the output capacitor to maintain stability. when the output capacitor is 47f or greater, the output capacitor should have less than 1 of esr . this will improve transient response as well as promote stability. ultralow esr capacitors, such as ceramic chi p capacitors may promote instability. these very low esr levels may cause an oscillation and/or underdamped tran-sie nt response. a low-esr solid tantalum capacitor works extremely well and provides good transient response and s tability over temperature. aluminum electrolytics can also be used, as long as the esr of the capacitor is < 1.the va lue of the output capacitor can be increased without limit. higher capacitance values help to improve transient resp onse and ripple rejection and reduce output noise. input capacitor an input capacitor of 1uf or greater is recommended when the de vice is more than 4 inches away from the bulk ac supply capacitance, or when the supply is a battery. small, sur face-mount, ceramic chip capacitors can be used for the bypass-ing. larger values will help to improve ripple rejec tion by bypassing the input to the regulator, further improving the integrity of the output voltage.transient respons e and 3.3v. fig 1. capacitor requirements
5a low-voltage low-dropout regulator lm39500/39501/39502 htc ? 6 ? minimum load current the lm39500/1/2 regulator is specified between finite loads. if the output current is too small, leakage currents dominate a nd the output voltage rises. a 10ma minimum load current is necessary for proper regulation. transient response and 3.3v to 2.5v conversion the lm39500/1/2 has excellent transient response to varia-tions in input voltage and load current. the device has been designed to respond quickly to load current variations and input voltage variations. large output capacitors are not required to obtain this performance. a standard 47f output capacitor, preferably tantalum, is all that is required. larger values help to improve performance even further. by virtue of its low-dropout voltage, this device does not sat urate into dropout as readily as similar npn-based de- signs. when converting from 3.3v to 2.5v, the npn-based regulat ors are already operating in dropout, with typical dropout requirements of 1.2v or greater. to convert down to 2.5 v without operating in dropout, npn-based regulators require an input voltage of 3.7v at the very least. the lm39500 /1/2 regulator will provide excellent performance with an input as low as 3.0v. this gives the pnp-based regulators a distinct advantage over older, npn-based linear regulators does not have the headroom to dothis conversion. error flag the lm39501 version features an error flag circuit which monito rs the output voltage and signals an error condition when the voltage drops 5% below the nominal output voltage. the error flag is an open-collector output that can sink 10ma during a fault condition. low output voltage can be caused by a number of problems, inclu ding an overcurrent fault (device in current limit) or low input voltage. the flag is inoperative during overtemperatu re shutdown. enable input the lm39501 version features an enable input for on/off control of the device. its shutdown state draws zero current (only microamperes of leakage). the enable input is ttl/ cmos c ompatible for simple logic interface, but can be connected to up to 20v. adjustable regulator design the lm39502 allows programming the output voltage any-where bet ween 1.25v and the 16v 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 res istor values are calculated by: r1=r2(vout/1.250-1) where vo is the desired output voltage. figure 1 shows componen t definition. applications with widely varying load currents may scale the resistors to draw the minimum load curre nt required for proper operation.
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