microsemi integrated products 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 1 copyright ? 2000 rev. 1.2a, 2002-11-01 www. microsemi . com lx8816 dual channel 1a low dropout re g ulator p roduction d ata s heet integrated products description the lx8816 is a dual channel positive-voltage linear regulator. this dual regulator has one fixed output coupled with an adjustable output. each channel features low-dropout and high accuracy. the lx8816 provides designers with a flexible power management solution, minimal printed circuit board area and shorter design cycles. each channel can supply up to one amp independently with a regulator design optimized for system efficiency by consuming minimal ground current and directing quiescent current to the load. the lx8816 features on-chip trimming of the internal voltage enabling precise output voltages, typically 1% of it?s specified value, while the bipolar output transistor has a low dropout voltage even at full output current (v do < 1.2v typ. @ 1a). thermal and short circuit current protection are integrated on-chip and operate independently for each regulator output. the lx8816 regulator is stable with a low-value output capacitor, typically 2.2 f on the outputs, allowing designers flexibility in external component selection. microsemi?s s-pak package enables maximum power dissipation and ease of assembly using surface mount technology. important: for the most current data, consult microsemi ?s website: http://www.microsemi.com key features two independent regulated outputs accurate output voltages typical dropout of 1.2v at 1a and 1.1v at 500ma independent thermal and current limit protection low profile 5 lead smt power package low tolerance load regulation wide dc supply voltage of 4.3v to 10v loop stability independent of output capacitor type applicati ons/benefits 5v to 3.3v / adj regulators hard disk drives, cd-roms adsl and cable modems battery charging circuits instrumentation pc peripherals application circuits v 1 v 2 gnd adj v in lx8816-04 22f 10f 10 f v in = 5v 3.3v @ 1.0a 2.5v* @ 1.0a r1 499 r2 499 1 2 1 1 * 1 r i r r v v adj ref + ? ? ? ? ? ? ? + = package order info t j ( c) o utput v 1 (pin 4) o utput v 2 (pin 5) df plastic s-pak 5-pin 0 to 125 adj. 3.3v LX8816-04CDF note: available in tape & reel. append the letter ?t? to the part number. (i.e. LX8816-04CDFt) l l x x 8 8 8 8 1 1 6 6
microsemi integrated products 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 2 copyright ? 2000 rev. 1.2a, 2002-11-01 www. microsemi . com lx8816 dual channel 1a low dropout re g ulator p roduction d ata s heet integrated products absolute maximum ratings input voltage (v bat ).................................................................................................. 13.5v load current (intern ally limited)................................................................................... 1a power dissipati on ................................................................................... internal ly limited short-circuit protec tion ....................................................................................... inde finite operating junction temperature ................................................................................150 c lead temperature (sol dering 180 s econds) ...............................................................235 c note: exceeding these ratings could cause damage to th e device. all voltages are with respect to ground. currents are positive into, ne gative out of specified terminal. thermal data df plastic s-pak 5-pin t hermal r esistance -j unction to t ab , jt 4.5c/w t hermal r esistance -j unction to a mbient , j a 24.5c/w junction temperature calculation: t j = t a + (p d x ja ). the ja numbers are guidelines for the therma l performance of the device/pc-board system. all of the above assume no ambient airflow. ja can vary from 25 c/w to > 40 c/w depending on mounting technique. (see application notes section: thermal considerations) package pin out 1 2 3 4 5 v 2 v 1 gnd adj v in tab is gnd df p ackage (top view) functional pin description p in n ame d escription v in positive unregulated supply input for the regulator. bypass to gnd with at least 2.2f capacitance having low esr for good transient response. adj adjustable input . the output voltage can be set by two external resistors with the following relationship: v 1 = v ref * (1 + r1 / r2) + i adj * r1 where r1 is the resistor connected between v 1 and adj, and r2 is the resistor connected between adj and gnd. gnd common terminal for ground reference. the input and output bypass capacitors should be connected to this pin. in addition the tab on the s-pak package and pin 3 are also used for heat sinking the device. v 1 adjustable regulator output (regulator #1) it is recomme nded to bypass to gnd with at least 2.2uf. size your output capacitor to meet the transi ent loading requirement. if you have a very dynamic load, a lower esr capacitor will improve the response to these load steps. v 2 fixed regulator output (regulator #2). it is recommended to bypass to gnd with at least 2.2f. size your output capacitor to meet the transient load ing requirement. for dynamic loads, a lower esr capacitor will improve the response to these load steps. p p a a c c k k a a g g e e d d a a t t a a
microsemi integrated products 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 3 copyright ? 2000 rev. 1.2a, 2002-11-01 www. microsemi . com lx8816 dual channel 1a low dropout re g ulator p roduction d ata s heet integrated products recommended operating conditions lx8816-04 parameter symbol min typ max units input voltage v in 4.5 10 v output voltage (adjustable) v out 5.5 v load current each output (with adequate heat sinking) 0 1000 ma input capacitor (v in to gnd) 2.2 20 f output capacitor (v out to gnd) 1.0 10* f * size your output capacitor to meet the transi ent loading requirement. if you have a very dynamic load, a lower esr and larger value capacitor will improve the response to these load steps. electrical characteristics unless otherwise specified, the following specificati ons apply over the operat ing ambient temperature 0 c t a 125 c except where otherwise noted and the following test conditions: v in = 5v, i out = 10ma, c 1 = 10 f (tantalum), c 2 = c 3 = 4.7 f (tant.), & t j = t a using low duty cycling methods. lx8816-04 parameter symbol test conditions min typ max units ` adjustable output (output 1) reference voltage v ref 5ma < i 1 < 1a, 4.75v < v in < 10v 1.225 1.25 1.273 v line regulation ? v 1 (v in ) 4.75v < v in < 5.5v, i out = 5ma 1.5 2.5 mv line regulation ? v 1 (v in ) 4.50v < v in < 10v, i out = 5ma 0.17 0.22 %v load regulation ? v ref (i 1 ) 5ma < i 1 < 1a, v in = 4.75v 0.04 0.15 %v dropout voltage ? v i load = 1a, ? v 1 = -2% 1.2 1.3 v current limit i out (max) 1.0 1.4 a minimum load current i l note 1, the external resistor divider current can be included in this requirement. 2 3 ma adjust pin bias current i adj bias current flows into part. 0.12 1 a ` fixed output (output 2) output voltage v 2 5ma < i 2 < 1a, 4.75v < v in < 10v 3.234 3.30 3.3825 v line regulation ? v 2 (v in ) 4.75v < v in < 5.5v, i out = 5ma 6 8 mv line regulation ? v 2 (v in ) 4.50v < v in < 10v, i out = 5ma 0.17 0.22 %v load regulation ? v 2 (i 2 ) 5ma < i 2 < 1a, v in = 4.75v 2.6 6 mv dropout voltage ? v i load = 1a, ? v 2 = -2% 1.2 1.3 v current limit i out (max) 1.0 1.4 a minimum load current i l note 1 0 ma ` entire regulator quiescent current i q v in < 10v, i 1 = 5ma, i 2 = 5ma 2.6 3.8 ma quiescent current iq v in < 10v, i 1 = 1a, i 2 = 1a 3.5 6 ma ripple rejection psrr f=120hz, v in = 5v 60 75 db rms output noise (% of v out ) v out (rms) 10hz < f < 10khz 0.003 %v thermal shutdown t jsd 135 140 c note 1: minimum load current is defined as the am ount of output current required to maintain regulation. e e l l e e c c t t r r i i c c a a l l s s
microsemi integrated products 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 4 copyright ? 2000 rev. 1.2a, 2002-11-01 www. microsemi . com lx8816 dual channel 1a low dropout re g ulator p roduction d ata s heet integrated products block diagram bias 1.25v v ref 1 v in 4 2 v out1 c 1 10 f r 1 r 2 c 3 10 f 1 2 1 1 25 . 1 1 r adj i r r out v + ? ? ? ? ? ? ? ? + = note: application circuit above using ceramic capacitors. r1 and r2 used with adjustable version only. (adjustable) + - 5 v out2 c 2 10 f gnd 3 + - v in (fixed) figure 1 ? simplified block diagram b b l l o o c c k k d d i i a a g g r r a a m m
microsemi integrated products 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 5 copyright ? 2000 rev. 1.2a, 2002-11-01 www. microsemi . com lx8816 dual channel 1a low dropout re g ulator p roduction d ata s heet integrated products characteristic curves load transient response v in = 20f ceramic, esr= 45m ? ; v1,v2 = 10f ceramic, esr= 75m ? 50mv / div 2s / div 50mv / div 1a v2 = 3.3v 1a step load v1 = 1.5v 180 ? load 1ma load transient response v in = 22f tantalum, esr=232m ? ; v1,v2 = 10f tantalum, esr=198m ? 50mv / div 2s / div 50mv / div 1a v in = 5v 0ma v1 = 1.5v v2 = 3.3v 1a step load 50mv / div turn on characteristics 500mv / div 100s / div 1v / div v2 = 3.3v v in = 5v v1 = 1.5v 500m v / div current limit response 20mv(a c) / div 100s / div 500mv / div v1 = 1.5v v2 = 3.3v 1.2a 200ma / div rising load on v2 ripple rejection vs. frequency v in = 5v, c in = 22f, c out1,2 = 10f, v 2 =3.3v, i out2 =1a 0 5 10 15 20 25 30 35 40 45 100 1000 10000 100000 frequency (hz) ripple rejection (db) v out and i chip vs. v in ramp 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 v in (volts) v out (volts) 0 1 2 3 4 5 6 ichip (ma) ichip, ma v2,(rext=13k ohms) v1, adj(rext=909 ohms) c c h h a a r r t t s s
microsemi integrated products 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 6 copyright ? 2000 rev. 1.2a, 2002-11-01 www. microsemi . com lx8816 dual channel 1a low dropout re g ulator p roduction d ata s heet integrated products application information description the lx8816 is part of a family of dual ldo (low drop-out) linear regulators in microsemi?s s-p ak power package, which offer maximum power dissipation in a low profile surface mount technology. the family includes co mbination fixed and adjustable versions. each channel can supply up to one amp independently with a regulator design optimized for sy stem efficiency by consuming minimal ground current and directing quiescent current to the load. input capacitor to improve load transient response and noise rejection a input bypass capacitor is of at least 2.2uf is required. generally we recommend a 20uf ceramic or tant alum or 22uf electr olytic capacitor. output capacitor the regulator requires output ca pacitors connected between v 1 , v 2 and gnd to stabilize th e internal co ntrol loop. many types of capacitors are available, with different capacitance values tolerances, temperature coefficients and equivalent series resistance. we recommend a minimum of 4.7uf. to ensure good transient response from the power supply system under rapidly cha nging current load conditions, designers generally use additional output capacitors connected in parallel. such an arrangement serves to minimize the effects of the parasitic resistance (esr) and inductance (esl) that are present in all capacitors. the regulator has been tested stable with capacitor esr?s in the range of 0.05 to 2 ohms. we have found it best to use the same type of capacitor for both input and output bypass. adjustable output voltage the lx8816 develops a 1.25v refere nce voltage between the adjust terminal and gnd (see figure 2). by placing a resistor, r2, between these two terminals, a constant curre nt is caused to flow through r1 and down through r2 to set the overall output voltage. because i adj is very small and constant when compar ed with the current through r2, it represents a small error a nd can usually be ignored. lx8816-04 r1 r2 v in adj v 1 figure 2 - basic adjustable regulator v ref 1 2 1 1 1 r i r r v v adj ref + ? ? ? ? ? ? ? + = i adj 1a v 2 minimum load requirement the lx8816 has a minimum load is requirement for proper output regulation. this minimum current is specified at 0ma for the fixed output and 2ma for the adjustable output regulators. temperature protection the thermal protection shuts the lx8816 down when the junction temperature exceeds 140 0 c. each output has independent thermal shutdown capability. exposure to absolute maximum rated conditions for extended periods may affect device reliability, see thermal considerations below. current limit protection the lx8816 includes over current protection, when the output load current exceeds typically 1.4a the circuit forces the regulator decrease in output. thermal considerations thermal shutdown protects the integrated circuit from thermal overload caused from a rise in j unction temperature during power dissipation. this means of protection is intended for fault protection only and not as a means of curr ent or power limiting during normal application usage. proper thermal ev aluation should be done to ensure that the junction temperature dose not exceed it?s maximum rating. operating at the maximum t j of 150c can impact reliability . due to variation in individual device electrical characteristics and thermal resistance , the built in thermal overload protection may be activated at p ower levels slightly above or belo w the rated dissipation. also peak output power should be consider ed for each individual output. power dissipation for regulator can be calculated using the following equation: p d = (v in(max) -v 1 ) * i 1 + (v in(max) -v 2 ) * i 2 (note: power dissipation resulting from qu iescent (ground) current is negligible) for the s-pak package, thermal resistance, tab-amb is 25-45 0 c/w depending on mounting technique when mounted on a fr4 copper clad pcb. junction temperature of the integrated circuit can be calculated using: t junction = t junction-tab rise _ + t tab-amb rise + t amb t tab = p d max * jt ; t tab-amb = (p d reg1 + p d reg2 ) * pcb an example: given conditions: t a = 50c, v in = 5.0v, v 1 = 2.5v, i 1 = 210ma, v 2 = 3.3v i 2 = 1a. calculated values: t j-tab reg1 = (5v-2.5v) * (210ma) * 4.5c/w = (0.525) * 4.5c/w = 2.4c t j-tab reg2 = (5v-3.3v) * (1.0a) * 4.5c/w = (1.7) * 4.5c/w = 7.7c t tab-amb rise = ( 0.525w + 1.7w ) * 30c/w = 66.8c t junction = 10.1c + 66.8c + 5 0c = 126.9c it is important to note that although each output of the regulator will produce up to 1a in current, the individual or total power dissipation may limit the useful total current draw. the junction temperature should be calculated for each individual output as well as the combined outputs to insure the maximum junction temperature in not exceeded. a a p p p p l l i i c c a a t t i i o o n n
microsemi integrated products 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 7 copyright ? 2000 rev. 1.2a, 2002-11-01 www. microsemi . com lx8816 dual channel 1a low dropout re g ulator p roduction d ata s heet integrated products application information layout consideration the layout must be done with low impedance paths for v in , v 1, v 2 and ground by using sufficiently wide tr aces to avoid voltage drops and noise pick up. the output capacitors must be placed as close as possible to the voltage regulator output pins. to allow the same voltage reference for all circuits, use a star configuration from the output capacitors to the different loads. the input capacitor should be connected between v in and ground with short leads. although it may not be immediately obvious, best lo ad regulation for the adjustable output is obtained when the top of the resistor divider, ( r 1), is connected as close as possible to the case of the regulator, not to the load . heatsink consideration the pcb co p per can be used as a heatsink for the surface mounted s-pak. using the minimum size as shown in the recommended pad layout limits the usable power to about 1w for ambient temperature of 50c. since most applications requi re greater than 2w there is the need to provide additional heat sinking. this can be accomplished by using additional copper area both on the pcb surface as shown in the p ossible heat sink layout below, or to an embedded ground plane. since the die pad (copper tab) is in electrical contact with ground, the designer can use thermal vias on the surface of the pcb taking advantage of the heat-spreading (cu) layer of an internal ground plane. heat sink layout board level ground plane component trace b a component component trace ground plane inner power plane backside trace vias b a figure 3 - heatsink recommended minimum pcb footprint 11.56mm 9.98mm 8.84mm 3.28mm .86mm 1.83mm 4.39mm 5.36mm 7.92mm 9.75mm 8.89mm 0mm 1.37mm a a p p p p l l i i c c a a t t i i o o n n
microsemi integrated products 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 8 copyright ? 2000 rev. 1.2a, 2002-11-01 www. microsemi . com lx8816 dual channel 1a low dropout re g ulator p roduction d ata s heet integrated products package dimensions df 5-pin plastic s-pak a b k f g j h c e i d l m m illimeters i nches dim min max min max a 9.27 9.52 0.365 0.375 b 7.87 8.13 0.310 0.320 c 1.78 2.03 0.070 0.080 d 8.03 bsc 0.316 bsc e 0.25 bsc 0.010 bsc f 0.63 0.79 0.025 0.031 g 1.70 bsc 0.067 bsc h 0.79 1.04 0.031 0.041 i 6.50 bsc 0.256 bsc j 0.03 0.13 0.001 0.005 k 10.41 10.67 0.410 0.420 l 0.25 bsc 0.01 bsc m 0.76 1.27 0.03 0.05 note: dimensions do not include mold flash or pr otrusions; these shall not exceed 0.155mm(.006? ) on any side. lead dimension shall n ot include solder coverage. m m e e c c h h a a n n i i c c a a l l s s
microsemi integrated products 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 9 copyright ? 2000 rev. 1.2a, 2002-11-01 www. microsemi . com lx8816 dual channel 1a low dropout re g ulator p roduction d ata s heet integrated products notes production data ? information contained in this document is proprietary to microsemi and is current as of publication date. this document may not be modified in any way without the express written consent of microsemi. product processing does not necessarily include testing of all parameters. microsemi reserves the right to change the configuration and performance of the product and to discontinue product at any time. n n o o t t e e s s
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