1 date: 1/19/05 spx1581 5a ultra low dropout voltage regulator copyright 2005 sipex corporation spx1581 description features low dropout voltage 500mv at 5a full load current adjustable ouput down to 1.2v from atx power supply fixed output voltages of 3.3v, 2.8v and 2.5v extremely tight load and line regulation standard 5-terminal low cost to-220 and to-263 the spx1581 is a 5a low dropout regulator with extremely low dropout voltage. the adjustable version requires only two external resistors to set the output voltage. the fixed version has a preset output of 3.3v, 2.8v or 2.5v and does not require any external resistors. the spx1581 features a low dropout of 400mv(typ.) and offers fast transient response. this device is suitable for pentium applications requiring 2.8v, 2.5v from 3.3v atx power supplies, where a low current input voltage 1v greater than the output voltage is needed. with an external sense pin the load regulation is less than 1mv. this device is an excellent choice for the use of powering low voltage microprocessors that require a lower dropout, fast transient response to regulate from 3.3v and 5v supplies. the spx1581 is also an excellent choice as a post regulator for switching supplies applications. the spx1581 offers protection against over-current faults, reversed input polarity, over temperature operation and positive and negative transient voltage. the spx1581 is offered in a 5 pin to-220 and to-263 compatible with industry standard 5-terminal regulators. for 7a, 3a and 1.5a ultra low dropout versions refer to spx1580, spx1582 and spx1583 data sheets respectively. 5a ultra low dropout voltage regulator fast response, adjustable & fixed applications 3.3v to 2.8v atx power supplies 3.3v to 2.9v for portable pentium tm processor 5v to 3.5v vre supply high efficiency "green" computer systems 13 25 4 spx1581 5 pin to-263 sense adj or fixed v out v cntrl v in 3 2 1 spx1581 5 pin to-220 sense adj or fixed v out v cntrl v in 4 5 c4 2x330 f 2.5v v out r1 124 ? r2 124 ? v out sense c2 10 f v ctrl c1 330 f 3.3v v in 5v v ctrl spx1581 5 4 2 3 1 (1) v ctrl needed when v in < 5v. (2) v out = v ref (1+r 2 /r 1 )+i adj r 2 . (3) v ref is measured across adjust to sense. adj v in c3 .033 f c4 2x330 f 2.5v v out v out sense c2 10 f v ctrl c1 330 f 3.3v v in 5v v ctrl spx1581 5 4 2 3 1 (1) v ctrl needed when v in < 5v. gnd v in typical fixed regulator adjustable regulator typical applications circuit now available in lead free packaging
2 date: 1/19/05 spx1581 5a ultra low dropout voltage regulator ?opyright 2005 sipex corporation power dissipation ..................................... internally limited storage temperature range ..................... -65 c to +150 c operating junction temperature range spx1581 control section ............................. 0 c to +125 c spx1581 power transistor .......................... 0 c to +150 c electrical characteristics electrical characteristics at v out = v sense , v adj = 0v, t a =25 c, c ctl = c pwr = c out = 33 f tantalum cap otherwise specified. the ? denotes the specifications which apply over full temperature range -40 c to +85 c, unless otherwise specified. parameter min typ max units ? conditions 2.5v version output voltage 2.450 2.5 2.550 v v ctrl = 6.0v to 12v, v in = 3.0v to 5.0v, i o =10ma 2.400 2.600 ? i o = 10ma to 5a 2.8v version output voltage 2.744 2.8 2.856 v v ctrl = 6.3v to 12v, v in =3.3v to 12v, i o =10ma 2.688 2.912 ? i o = 10ma to 5a 3.3v version output voltage 3.234 3.3 3.366 v v ctrl = 6.3v to 12v, v in = 3.3v + 0.8v, i o =10ma 3.168 3.3 3.432 ? i o = 10ma to 5a all voltage options reference voltage 1.238 1.25 1.263 v v ctrl = 2.75v, v in = 2.00v, i o = 10ma v ctrl =2.7v to 12v,v in = 2.05v to 5.5v,i o =10ma to 5a line regulation mv v ctrl = 2.5v to 12v, v in = 1.75v to 5.5v, i o =10ma 1.0 3.0 ? v adj =0v load regulation (note 1) 1.0 5.0 mv ? v ctrl = 2.75v, v in = 2.1v, i o =10ma to 5a, v adj = 0v dropout voltage min. v ctrl 1.10 1.25 v v adj = 0v (note 2) (v ctrl - v out )v in = 2.05v, i o = 1a dropout voltage min. v in 0.40 0.50 v v adj = 0v (note 2) (v in - v out )v in = 2.75v, i o = 5a current limit 5.1 a v ctrl = 2.75v, v in = 2.05v, ? v out = 100mv, v adj = 0v minimum load current 5 10 ma ? v ctrl = 5v, v in =3.3v, v adj =0v thermal regulation 0.002 0.02 %/w 30ms pulse ripple rejection 60 80 db v ctrl = 3.75v, v in = 3.75v, i o = 2.5a, v adj =0v t j =25, v ripple =1vpp at 120hz control pin current 60 120 ma ? v adj = 0v v ctrl = 2.75v, v in = 2.05v, i o = 5a adjustble pin current 50 av ctrl = 2.75v, v in = 2.05v, v adj =0v, i o = 10ma 120 ? thermal resistance 3 c/w junction to case ( jc ) to-220-5 50 c/w junction to ambient ( ja ) thermal resistance 3 c/w junction to case ( jc ) to-263-5 60 c/w junction to ambient ( ja ) input supply voltage ..................................................... 6v v ctrl input voltage ....................................................... 13v absolute maximum ratings note 1: low duty cycle pulse testing with kelvin connections is required to order to maintain accurate data. note 2: dropout voltage is defined as the minimum differential between v in and v out or v ctrl and v out required to maintain regulation at v out 95% nominal v out . note 3: v ref is measured across adjust pin to sense pin.
3 date: 1/19/05 spx1581 5a ultra low dropout voltage regulator copyright 2005 sipex corporation current limit amplifier thermal overload v ref voltage regulation amplifier limit sense (4) v ctrl v in (5) v out (3) sense (1) adj (2) s.o.a pin number pin name description 1 sense allows kelvin sense of v out at the load. (positive side of the reference voltage of the device). 2 adj negative side of the reference voltage for the device. adding a small bypass capacitor from the adj pin to ground will improve the transient response. 3v out power output of the device. 4v ctrl supply pin for the control circuitry of the device. the current flow into this pin will be about 1% of the output current. v ctrl must be between 1.0v and 1.3v greater than the output voltage for the device to regulate. 5v in output load current is supplied through this pin. v in must be between 0.1v and 0.8v greater than the output voltage for this device to regulate. pin description functional diagram
4 date: 1/19/05 spx1581 5a ultra low dropout voltage regulator ?opyright 2005 sipex corporation adjustable regulator design 1.25v reference voltage is being developed be- tween the sense pin and the adj pin of the spx1581. adding two external resistors (see fig 1.) will allow setting the output voltage from 1.25v to 6v. r 1 is chosen so that this current is specified minimum load current of 10ma. r 2 is given by the formula: v out = v ref (1+ r 2 /r 1 ) + i adj (r 2 ). the current flowing from the adj pin is typicaly 50 a. this adj pin contributes to the final v out but is usually neglected. connecting the sense pin to the top of the resis- tor divider will improve load regualtion. lowering noise using the sense pin to kelvin the load will increase accuracy of the output voltage during load regulation. for the fixed voltage device, adding a capacitor at the gnd pin will improve transient response. this capacitor is chosen in the range of 1 f to 0.1 f and will depend on the amount of output capacitance in the system. application notes a typical application would use 5v for v in and 3.3v for v ctrl from a motherboard power supply to provide a nominal 2.5v output. using the sense pin allows kelvin measure the output, reducing resistance-associated errors. the spx1581 can power the 2.5v core voltage for microprocessors such as a pentium tm , p55c tm , amd5k86 tm and k6 tm and the ibm powerpc tm 603ev and 604ev processors. power sequencing of v in and v ctrl is re- quired. apply v in before v ctrl for proper operation the spx1581 is designed as a high performance and low cost solution for application requiring a lower dropout than traditional npn regulators. the spx1581 uses a separate input voltage v ctrl ( v ctrl v out + 1.3v) to minimize the dropout voltage. this allows the 2.5v power for the load to come from a 3.3v system supply. as added benefit this will reduce the heat dissi- pation*, and lower heatsink and cooling fan cost. * the reduction of heat dissipation is a result of the increase of the regulator efficiency (efficiency = v out /v in ).
5 date: 1/19/05 spx1581 5a ultra low dropout voltage regulator copyright 2005 sipex corporation package: 5 pin to-220 h1 b seating plane a1 a chamfer optional c a2 a a c with plating base metal b contact area l c c dd b e1 e e ? q d d1 e2 e/2 l1 1 e symbol min nom max a0.16- 0.19 a1 0.02 - 0.055 a2 0.08 - 0.115 b0. 015 0.027 0.04 b2 0.045 - 0.07 c0. 014 - 0.024 d0.56- 0.65 d1 0.33 - 0.355 d2 0.48 - 0.507 e0.38- 0.42 e1 0.27 - 0.35 e2 - - 0.03 e e1 h1 0.23 - 0.27 l1 - - 0.25 l2 --- ?p 0.139 - 0.161 q0.1-0 .135 note: dimensions in (mm) 5 pin to-220 jedec to-220 (ac) variation .100 bsc .100 bsc
6 date: 1/19/05 spx1581 5a ultra low dropout voltage regulator ?opyright 2005 sipex corporation package: 5 pin to-263 c with plating base metal (b) contact area 1 23 4 5 e e l2 5x b e 4x (datum a) c c2 a h seating plane d1 l1 (e) e1 l 0?8 l3 symbol min nom max a 0.16 - 0.19 a1 0 - 0.01 b 0.02 - 0.039 c 0.015 - 0.029 c2 0.45 - 0.23 d1 0.27 - - e 0.38 - 0.42 e1 0.245 - - e h 0.575 - 0.625 l 0.07 - 0.11 l1 - - 0.066 l2 - - 0.07 l3 note: dimensions in inches 5 pin to-263 jedec to-263 (bb) variation .067 bsc .010 bsc
7 date: 1/19/05 spx1581 5a ultra low dropout voltage regulator copyright 2005 sipex corporation corporation analog excellence sipex corporation reserves the right to make changes to any products described herein. sipex does not assume any liability aris ing out of the application or use of any product or circuit described herein; neither does it convey any license under its patent rights nor t he rights of others. sipex corporation headquarters and sales office 233 south hillview drive milpitas, ca 95035 tel: (408) 934-7500 fax: (408) 935-7600 ordering information part number accuracy output voltage packages spx1581u5 ............................... 2.0% ............................. adj .......................... 5-pin to-220 spx1581u5-2.5 ......................... 2.0% ............................ 2.5v ........................ 5-pin to-220 spx1581u5-2.8 ......................... 2.0% ............................ 2.8v ........................ 5-pin to-220 spx1581u5-3.3 ......................... 2.0% ............................ 3.3v ........................ 5-pin to-220 spx1581t5 ................................ 2.0% ............................. adj .......................... 5-pin to-263 spx1581t5/tr .......................... 2.0% ............................. adj .......................... 5-pin to-263 spx1581t5-2.5 .......................... 2.0% ............................ 2.5v ........................ 5-pin to-263 spx1581t5-2.5/tr .................... 2.0% ............................ 2.5v ........................ 5-pin to-263 spx1581t5-2.8 .......................... 2.0% ............................ 2.8v ........................ 5-pin to-263 spx1581t5-2.8/tr .................... 2.0% ............................ 2.8v ........................ 5-pin to-263 spx1581t5-3.3 .......................... 2.0% ............................ 3.3v ........................ 5-pin to-263 spx1581t5-3.3/tr .................... 2.0% ............................ 3.3v ........................ 5-pin to-263 available in lead free packaging. to order add "-l" suffix to part number. example: spx1581t5-3.3/tr = standard; spx1581t5-l-3.3/tr = lead free /tr = tape and reel pack quantity is 500 for to-263. click here to order samples
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