bay linear, inc 2478 armstrong street, livermore, ca 94550 tel: (925) 606-5950, fax: (925) 940-9556 www.baylinear.com 5.0a low dropout voltage regulator B1581 adjustable & fix output pin connection ordering information devices package temp. B1581t to-220 0 c to 70 c B1581s to-263 0 c to 70 c description the bay linear B1581 is monolithic low power 5.0a adjustable and fixed npn voltage regulator that are easy to use with minimum external components. it is suitable for applications requiring a well-regulated positive output voltage with low input-output differential voltage requirements and output voltage 1.5v, 2.5v, 3.0v, 3.3v, or 5v. the B1581 outstanding features include full power usage up to 5.0amp of load current internal current limiting and thermal shutdown. other fixed versions are also available consult with factory. the B1581 is offered in a 5-pin to-220, & to-263 packages compatible with other 5 terminal regulators. for 5a low dropout regulator refer to the B1581 data sheet. features ? adjustable output down to 1.2v ? fixed output voltages 2.5v, 3.0v 3.3v, and 5.0v ? output current of 5.0a ? low dropout voltage 700mv typ. ? current & thermal limiting ? standard 3-terminal low cost to-220, d 2 packages ? similar to industry standard ez1581/cs5205 applications ? 3.3v to 2.5v for pentium processor ? smps post regulator ? high efficiency ?green? computer systems ? high efficiency linear power supplies ? 5v to 3.xxv fro pentium processor ? battery charger v power output 1 2 3 4 5 v control adj/gnd. sense to-263-5 package v power v power output 1 2 3 4 5 v control v control adj/gnd. sense to-263-5 package bay linear bay linear bay linear bay linear ins p ire the linear power ins p ire the linear power ins p ire the linear power ins p ire the linear power
bay linear, inc 2478 armstrong street, livermore, ca 94550 tel: (925) 606-5950, fax: (925) 940-9556 www.baylinear.com B1581 absolute maximum rating parameter symbol value unit maximum input voltage v in 7 v power dissipation p o internally limited w thermal resistance junction to case jc 3 thermal resistance junction to ambient ja 50 c/w operating junction temperature range control section power transistor t j 0 to 125 0 to 150 storage temperature range t stg -65 to 150 lead temperature (soldering 10 sec.) t lead 260 c electrical characteristics (v in = 4.75v to 5.25v; i o = 10ma to 5.0amp, unless otherwise specified) parameter symbol conditions min typ max unit 1.485 1.515 v cont =4v, v pwr =2v v cont =3v, v pwr =2.3v, i load =10ma to 5a 1.475 1.5 1.525 2.475 2.525 v cont =5v, v pwr =3.3v v cont =4v, v pwr =3.3v, i load =10ma to 5a 2.460 2.5 2.540 2.970 3.030 v cont =5.5v, v pwr =3.5v v cont =4.5v, v pwr =3.8v, i load =10ma - 5a 2.950 3.0 3.050 3.267 3.333 v cont =5.8v, v pwr =3.8v v cont =4.8v, v pwr =4.1v, i load =10ma - 5a 3.247 3.3 3.353 4.950 5.050 output voltage v o v cont =7.5v, v pwr =5.5v v cont =6.5v, v pwr =5.8v, i load =10ma- 5a 4.920 5.0 5.080 v 1.238 1.262 reference voltage v ref v cont =2.75v, v pwr =2v, i load =10ma v cont =2.7v, to 12v v pwr =3.3v to 5.5v, i load =10ma to 5a 1.230 1.250 1.270 v line regulation (1) reg (line) i o = 10ma, v in =5v, t= 25 c 0.04 0.2 0.08 0.40 load regulation (1) reg (load) i o = 10ma, v in =5v, t= 25 c % 0.10 0.17 dropout voltage v pwr -v out v cont =v out +2.5v, i load =10ma v cont =v out +2.5v, i load =5a 0.55 0.70 v minimum load current i min 5 10 ma current limit i s (v in -v out )=3v 5.5 6.8 a ground pin current i q v in =5v 6 10 ma temperature stability t s i o = 10ma, v in =5v 0.5 % thermal regulation t= 25 c, 30ms pulse 0.003 %/w ripple rejection r a t= 25 c, v in =5v 60 80 db thermal resistance - to-220 junction to tab junction to ambient dd package junction to tab junction to ambient 3.0 60 3.0 60 3.0 60 3.0 60 c/w note: output switch tests are performed under pulsed conditions to minimize power dissipation
bay linear, inc 2478 armstrong street, livermore, ca 94550 tel: (925) 606-5950, fax: (925) 940-9556 www.baylinear.com B1581 block diagram pin 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. 3. v out = power output of the device. 4. v 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. 5. v 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 the device to regulate. (4) v ctrl v in (5) s.o.a v out (3) limit sense current limit amplifier thermal overload voltage regulation amplifier v ref sense (1) adj (2)
bay linear, inc 2478 armstrong street, livermore, ca 94550 tel: (925) 606-5950, fax: (925) 940-9556 www.baylinear.com B1581 applications notes the B1581 is designed as a high performance and low cost solution for application requiring a lower dropout than traditional npn regulators. the B1581 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 dissipation, and lower heat sink and cooling fan cost. a typical application would use 5v for vin and 3.3v for v ctrl from a motherboard power supply to provide a nominal 2.5v output. using the sense pin allows to kelvin measure the output, reducing resistive-associated errors. the B1581 can power the 2.5v core voltage for microprocessors such as pentium ? , p55c ? , amd5k86 ? and k6 ? and the ibm powerpc ? 603ev and 604ev processors. *the reduction of heat dissipation is a result of the increase of the regulator efficiency (efficiency = v out / v in ). adjustable regulator design 1.25v reference voltage is being developed between the sense pin and the adj pin of the as1581. 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 typically 50 a. this adj pin contributes to the final vout but is usually neglected. connecting the sense pin to the top of the resistor divider will improve load regulation. lowering noise using the sense pin to kelvin the load will increase accuracy of the output voltage during load regulation. for the fixed voltage devices, 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. typical application bay linear B1581 sense adj v in v ctrl r1 124 c4 2 x 330uf c2 10uf c1 330uf 5v v ctrl 3.3v v in 1 2 3 4 5 c3 .033uf (1) v ctrl needed when v in < 5v. (2) v out = v ref (1 + r2/ r1) + i adj r2. (3) v ref is measured across adjust to sense. 2.5v v out ? r1 124 ? v out fig. 1 adjustable regulator
bay linear, inc 2478 armstrong street, livermore, ca 94550 tel: (925) 606-5950, fax: (925) 940-9556 www.baylinear.com B1581 bay linear B1581 sense fixed v in v ctrl c4 2 x 330uf c2 10uf c1 330uf 5v v ctrl 3.3v v i n 1 2 3 4 5 c3 . 033uf (1) v ctrl is needed when v in <5v. fig.2 typical fixed regulator 2.5v v out v out 0.405 0.005 0.055 (1.397) 0.356 0.005 (10.287 0.127) (9.042 0.127) (15.24 0.635) 0.600 0.025 (1.702 0.127) 0.067 0.005 (0.813 0.076) 0.032 0.003 0.176 0.005 (4.470 0.127) 0.050 0.002 (1.270 0.051) 0.015 + - 0.003 0 8 (0.381 0.074) + - 0.100 0.010 (2.540 0.254)
bay linear, inc 2478 armstrong street, livermore, ca 94550 tel: (925) 606-5950, fax: (925) 940-9556 www.baylinear.com B1581 to-220-5 advance information - these data sheets contain descriptions of products that are in development. the specifications are based on the engineering ca lculations, computer simulations and/ or initial prototype evaluation. preliminary information - these data sheets contain minimum and maximum specifications that are based on the initial device characterizations. these lim its are subject to change upon the completion of the full characterization over the specified temperature and supply voltage ranges. the application circuit examples are only to explain the representative applications of the devices and are not intended to gua rantee any circuit design or permit any industrial property right to other rights to execute. bay linear takes no responsibility for any problems related to any industrial property right resulting from the use of the contents shown in the data book. typical parameters can and do vary in different applications. customer?s technical experts must validate all operating parameters including ? typical? for each customer applic ation. life support and nuclear policy bay linear products are not authorized for and should not be used within life support systems which are intended for surgical implants into the body to support or sustain life, in aircraft, sp ace equipment, submarine, or nuclear facility applications wit hout the specific written consent of bay linear president. 0.108 + - 0.005 (2.74 + - 2.74) 0.400 + - 0.005 (10.16 + - 0.13) 0.150 d + - 0.005 (3.81d + - 0.13) 0.175 + - 0.005 (4.45 + - 0.13) 0.050 + - 0.005 (1.27 + - 0.13) 0.250 + - 0.005 (6.35 + - 0.13) 0.590 + - 0.005 (14.99 + - 0.13) seating plane 0.547 + - 0.005 (13.89 + - 0.005) 0.067 + - 0.005 (1.70 + - 0.127) 0.268 ref (6.81 ref) 0.268 ref 0.032 + - 0.005 (0.81 + - 0.13) 0.015 + - 0.005 (0.38 + - 0.13) 0.105 + - 0.005 (2.67 + - 0.13) 1.137 ref (28.88 ref) 7 typ.
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