rev. 10/30/00 spx2810 1a low dropout voltage regulator adjustable & fixed output, fast response features applications ? adjustable output down to 1.2v ? portable palmtop/notebook computer ? fixed output voltages 1.5v, 2.5v, 3.0v, 3.3v, 5.0v ? smps post-regulator ? output current of 1a ? disk drives ? low dropout voltage 1.2v typ. ? portable consumer equipment ? extremely tight load and line regulation ? portable instrumentation ? current & thermal limiting ? battery charger ? standard 3-terminal low cost to-220, to-263, to-252 & sot-223 product description the spx2810 is a low power positive voltage regulator designed to source 1a output current. this device is an excellent choice for use in battery-powered applications and portable computers. the spx2810 features very low quiescent current and very low dropo ut voltage of 1.2v at a full load and lower as output current decreases. this product is available as adjustable or fixed 1.5v, 2 .5v, 3.0v, 3.3v, and 5v output voltages. the spx2810 is offered in a 3-pin surface mount packages sot-223, to-220, to-252 & dd package. the output capacitor of 10 f or larger is needed for the output stability of spx2810 as required by most other regulator circuits pin connections front view to-220-3 (u) spx2810 1 23 adj/gnd v out v in top view to-263-3 (t) 1 spx2810 2 3 adj/gnd v out v in front view to-252 (r) adj/gnd v in v out 3 2 1 spx2810 top view sot-223 (m3) adj/ gnd v out v in spx2810 13 2
rev. 10/30/00 spx2810 absolute maximum ratings lead temp. (soldering, 10 seconds) .............................. 300c input voltage........................................... ............. 10v storage temperature range ............................ -65 to +150c input to output voltage differential .................... 10v operating junction temperature range ...................... spx2810 control section.......................... -45c +125c spx2810 power transistor.........................-45c +150c electrical characteristics (note 1) at i out = 10ma, t a =25 c, unless otherwise specified. parameter conditions typ spx2810a spx2810 units min max min max 1.5v version 1.485 1.515 1.470 1.530 output voltage (note 2) spx2810-1.5v, 0 < i out < 1a, 3.3v rev. 10/30/00 spx2810 electrical characteristics (cont.) long term stability t a =125oc, 1000 hrs. 0.3 (note 2) 1 1 % thermal regulation ( ? v out (pwr)) t a =25oc, 20 ms pulse 0.01 0.020 0.020 %/w temperature stability ( ? v out (t)) 0.25 % output noise, rms 10hz to 10khz t a =25oc 0.003 % vo 3.0 3.0 to-220 junction to tab junction to ambient 60 60 3.0 3.0 dd package junction to tab junction to ambient 60 60 15 15 thermal resistance sot-223 package junction to tab junction to ambient 156 156 the bold specifications apply to the full operating temperature range. note 1: changes in output voltage due to heating effects are covered under the specification for thermal regulation. note 2: fixed version only note 3: adjustable version only oc/w
rev. 10/30/00 spx2810 application hints the spx2810 incorporates protection against over-current faults, reversed load insertion, over temperature operation, and positive and negative transient voltage. however, the use of an output capacitor is required in order to improve the stability and the performances. stability the output capacitor is part of the regulator?s frequency compensation system. either a 22 f aluminum electrolytic capacitor or a 10 f solid tantalum capacitor between the output terminal and ground guarantees stable operation for all operating conditions. however, in order to minimize overshoot and undershoot, and therefore optimize the design, please refer to the section ?ripple rejection?. ripple rejection ripple rejection can be improved by adding a capacitor between the adj pin and ground as shown in figure 6. when adj pin bypassing is used, the value of the output capacitor required increases to its maximum (22 f for an aluminum electrolytic capacitor, or 10 f for a solid tantalum capacitor). if the adj pin is not bypass, the value of the output capacitor can be lowered to 10 f for an electrolytic aluminum capacitor or 4.7 f for a solid tantalum capacitor. however the value of the adj-bypass capacitor should be chosen with respect to the following equation: c = 1 / ( 6.28 * f r * r 1 ) where c = value of the capacitor in farads (select an equal or larger standard value), f r = ripple frequency in hz, r 1 = value of resistor r 1 in ohms. if an adj-bypass capacitor is use, the amplitude of the output ripple will be independent of the output voltage. if an adj- bypass capacitor is not used, the output ripple will be proportional to the ratio of the output voltage to the reference voltage: m = v out / v ref where m = multiplier for the ripple seen when the adj pin is optimally bypassed. v ref = reference voltage reducing parasitic resistance and inductance one solution to minimize parasitic resistance and inductance is to connect in parallel capacitors. this arrangement will improve the transient response of the power supply if your system requires rapidly changing current load condition. thermal consideration although the spx 2810 offers some limiting circuitry for overload conditions, it is necessary not to exceed the maximum junction temperature, and therefore to be careful about thermal resistance. the heat flow will follow the lowest resistance path, which is the junction-to-case thermal resistance. in order to insure the best thermal flow of the component, a proper mounting is required. note that the case of the device is electrically connected to the output. in case the case has to be electrically isolated, a thermally conductive spacer can be used. however do not forget to consider its contribution to thermal resistance. assuming: v in = 10v, v out = 5v, i out = 1.5a, t a = 50 c/w, heatsink case = 6 c/w, heatsink case = 0.5 c/w, jc = 3 c/w power dissipation under this condition p d = (v in ? v out ) * i out = 7.5w junction temperature t j = t a + p d * ( case - hs + hs + jc ) for the control sections t j = 50 + 7.5*(0.5+6=3) = 121.25 c 121.25 c < t j (max) for the control & power sections. in both case reliable operation is insured by adequate junction temperature.
rev. 10/30/00 spx2810 basic adjustable regulator output voltage consider figure 2. the resistance r 1 generates a constant current flow, normally the specified load current of 10ma. this current will go through the resistance r 2 to set the overall output voltage. the current i adj is very small and constant. therefore its contribution to the overall output voltage is very small and can generally be ignored. load regulation parasitic line resistance can degrade load regulation. in order not to affect the behavior of the regulator, it is best to connect directly the r 1 resistance from the resistor divider to the case, and not to the load. for the same reason, it is best to connect the resistor r 2 to the negative side of the load. output voltage the fixed voltage ldo voltage regulator are simple to use regulators since the v out is preset to the specifications. it is important however, to provide the proper output capacitance for stability and improvement. for most operating conditions a capacitance of 22uf tantalum or 100uf electrolytic will ensure stability and prevent oscillation. spx2810 fig.2 basic adjustable regulator v in v ref v out = v ref * ( 1 + r 2 /r 1 ) + i adj * r 2 i adj 50a v out r 2 r 1 spx2810 fig.3 basic adjustable regulator v in r 2 r 1 connect r 2 to load r l connect r 1 to case of regulator r p parasitic line resistance spx2810 basic fixed regulator v in v out 5v c1 10uf c2 10uf 3.3v
rev. 10/30/00 spx2810 typical applications in out adj spx2810 c 1 r 1 v out fig. 5 typical adjustable regulator v in load adj spx2810 fig. 4 1a current output regulator v in c 1 out in r 2 c 2 v out = v ref (1 + r 2 ) + i adj r 2 r 1 r 1 note a: v in(min) = (intended v out ) + (v dropout (max) ) spx2810 fig. 6 improving ripple rejection v in r 1 r 2 150f 10f* 121? 1% 365? 1% + + 10f c 1 *c 1 improves ripple rejection. xc should be ~ r 1 at ripple frequency. 5v adj in out (note a) v out spx2810 fig.7 5v regulator with shutdown v in 100f 121? 1% 365? 1% + + 10f 5v adj in out (note a) 1k 1k ttl input 2n3904 note a: v in(min) = (intended v out ) + (v dropout (max) )
rev. 10/30/00 spx2810 typical characteristics
rev. 10/30/00 spx2810 ordering information ordering no precision output voltage packages spx2810u 2% adj 3 lead to-220 spx2810u-1.5 2% 1.5v 3 lead to-220 spx2810u-2.5 2% 2.5v 3 lead to-220 spx2810u-3.0 2% 3.0v 3 lead to-220 spx2810u-3.3 2% 3.3v 3 lead to-220 spx2810u-5.0 2% 5.0v 3 lead to-220 spx2810au 1% adj 3 lead to-220 spx2810au-1.5 1% 1.5v 3 lead to-220 spx2810au-2.5 1% 2.5v 3 lead to-220 spx2810au-3.0 1% 3.0v 3 lead to-220 spx2810au-3.3 1% 3.3v 3 lead to-220 spx2810au-5.0 1% 5.0v 3 lead to-220 spx2810t 2% adj 3 lead to-263 spx2810t-1.5 2% 1.5v 3 lead to-263 spx2810t-2.5 2% 2.5v 3 lead to-263 spx2810t-3.0 2% 3.0v 3 lead to-263 spx2810t-3.3 2% 3.3v 3 lead to-263 spx2810t-5.0 2% 5.0v 3 lead to-263 spx1202at 1% adj 3 lead to-263 spx2810at-1.5 1% 1.5v 3 lead to-263 spx2810at-2.5 1% 2.5v 3 lead to-263 spx2810at-3.0 1% 3.0v 3 lead to-263 spx2810at-3.3 1% 3.3v 3 lead to-263 spx2810at-5.0 1% 5.0v 3 lead to-263 spx2810m3 2% a dj 3 lead sot-223 spx2810m3-1.5 2% 1.5v 3 lead sot-223 spx2810m3-2.5 2% 2.5v 3 lead sot-223 spx2810m3-3.0 2% 3.0v 3 lead sot-223 spx2810m3-3.3 2% 3.3v 3 lead sot-223 spx2810m3-5.0 2% 5.0v 3 lead sot-223 spx2810am3 1% a dj 3 lead sot-223 spx2810am3-1.5 1% 1.5v 3 lead sot-223 spx2810am3-2.5 1% 2.5v 3 lead sot-223 spx2810am3-3.0 1% 3.0v 3 lead sot-223 spx2810am3-3.3 1% 3.3v 3 lead sot-223 spx2810am3-5.0 1% 5.0v 3 lead sot-223 spx2810r 2% adj 3 lead to-252 spx2810r-1.5 2% 1.5v 3 lead to-252 spx2810r-2.5 2% 2.5v 3 lead to-252 spx2810r-3.0 2% 3.0v 3 lead to-252 spx2810r-3.3 2% 3.3v 3 lead to-252 spx2810r-5.0 2% 5.0v 3 lead to-252 spx2810ar 1% adj 3 lead to-252 spx2810ar-1.5 1% 1.5v 3 lead to-252 spx2810ar-2.5 1% 2.5v 3 lead to-252 spx2810ar-3.0 1% 3.0v 3 lead to-252 spx2810ar-3.3 1% 3.3v 3 lead to-252 spx2810ar-5.0 1% 5.0v 3 lead to-252
rev. 10/30/00 spx2810 signal processing excellence sipex corporation headquarters and main offices: 22 linnell circle billerica, ma 01821 tel: (978) 667-8700 fax: (978) 670-9001 e-mail: sales@sipex.com 233 south hillview drive milpitas, ca 95035 tel: (408) 935-7600 fax: (408) 934-7500 sipex corporation reserves the right to make changes to any products described herein. sipex does not assume any liab ility arising out of the application or use of any product or circuit descri bed hereing; neither does it convey any license under its patent rights nor the rights of others. corporation
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