microsemi integrated products division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 1 copyright ? 2000 rev. 1.3, 2005-02-24 www. microsemi . com lx432 low voltage adjustable precision shunt regulator p roduction d ata s heet tm ? description the lx432 series are low-voltage precision adjustable shunt regulators with a reference voltage of 1.24v. the output voltage may be set to any value between 1.24v and 20v by two external resistors. these devices offer low output impedance for improved load regulation ? typical output impedance is 200m ? . the lx432 series operates with an operating current as low as 80a, making these devices suitable for portable and micropower applications. low voltage operation enables the lx432 to be used in the feedback loop of isolated low voltage power supplies. the minimum output voltage is determined by the lx432 output voltage plus the forward voltage drop of the opto-coupler led (typically 1.24 + 1.4 = 2.64v minimum). see figure 12. the lx432 is offered in 3 lead sot-23 or to-92 packages, and is a drop-in replacement for the tl v431 and sc431l devices. important: for the most current data, consult microsemi ?s website: http://www.microsemi.com key features ? low voltage operation: 1.24v reference ? initial voltage reference accuracy 1% ? adjustable output voltage from vref to 20v ? typical output dynamic impedance less than 250m ? ? sink current capability 80a to 20ma ? direct alternative to tlv431 applications ? low voltage adjustable power supplies ? instrumentation ? computers ? portable equipment product highlight r2 r1 gnd v ka v in lx432 reference cathode anode package order info sc plastic sot-23 3-pin lp plastic to-92 3-pin t a ( c) sc package marking rohs compliant / pb-free transition dc: 0503 rohs compliant / pb-free transition dc: 0509 0 to 70 432c lx432csc lx432clp -40 to 85 432i lx432isc lx432ilp note: available in tape & reel. append the letters ?tr? to the part number . (i.e. lx432csc-tr) to-92 (lp) package also available in ammo-pack. l l x x 4 4 3 3 2 2
microsemi integrated products division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 2 copyright ? 2000 rev. 1.3, 2005-02-24 www. microsemi . com lx432 low voltage adjustable precision shunt regulator p roduction d ata s heet tm ? absolute maximum ratings (note 1) cathode to anode voltage (v ka )..................................................................-0.3v to +20v reference input current (i ref ) .....................................................................-50 a to 10a continuous cathode current (i k )............................................................... -25ma to 25ma operating junction temperature ................................................................................ 150c storage temperature ....................................................................................-65oc to 150c rohs / pb-free peak package solder reflow temperature (40 second maximum expos ure) ....................................................................260 c (+0,-5) note 1: 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 sc 3-pin plastic package (pc mounted) 220c/w thermal resistance ? junction to ambient, ja (non-pc mounted) 410c/w lp 3-pin plastic package thermal resistance ? junction to ambient, ja 156c/w junction temperature calculation: t j = t a + (p d x ja ). the ja numbers are guidelines for the ther mal performance of the device/pc-board system. all of the above assume no ambient airflow. package pin out anode ref cathode 1 2 3 sc p ackage ? 3-p in 3. c athode 2. a node 1. r ef lp p ackage ? 3-p in rohs / pb-free 100% matte tin lead finish (all views top view) block diagram + - v ref r e f ( r ) anode(a) cathode (k) figure 1 ? simplified block diagram 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 division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 3 copyright ? 2000 rev. 1.3, 2005-02-24 www. microsemi . com lx432 low voltage adjustable precision shunt regulator p roduction d ata s heet tm ? electrical characteristics unless otherwise specified, the following sp ecifications apply over the operating ambient temperature for the lx432c with 0 c t a 70 c and the lx432i with -40c < t a < 85c except where otherwise noted. lx432 parameter symbol test conditions min typ max units reference voltage v ref i k = 10ma, v ka = v ref , t a = 25c 1.228 1.24 1.252 v reference voltage drift (note 2) ? v ref i k = 10ma, v ka = v ref , 0c < t a < 70c 3 12 mv i k = 10ma, v ka = v ref , -40c < t a < 85c 4 20 mv ratio of v ref change in cathode voltage change (note 3) ka ref ? v ? v i k = 10ma, v ka = v ref to 16v, t a = 25c -1 -2.7 mv/v reference terminal current i ref i k = 10ma, v ka = v ref , t a =25c, r1=10k ? , r2=open 0.1 0.5 a i k = 10ma, v ka = v ref , 0c < t a < 70c 0.05 0.3 a reference current drift (note 2) ? i ref i k = 10ma, v ka = v ref , -40c < t a < 85c 0.1 0.4 a minimum cathode current for regulation i k(min) v ka = v ref , t a = 25c 55 80 a dynamic impedance z ka i k = 0.1ma to 15ma, v ka = v ref , t a = 25c 0.2 0.4 ? off-state cathode current i off v ka = 16v, t a = 25c 0.004 a note 2: these parameters are guaranteed by design. note 3: ka ref ? v ? v ratio of change in reference input voltage to the change in cathode voltage 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 division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 4 copyright ? 2000 rev. 1.3, 2005-02-24 www. microsemi . com lx432 low voltage adjustable precision shunt regulator p roduction d ata s heet tm ? characteristic curves stability boundary condition? 0 5 10 15 20 25 30 0.001 0.010 0.100 1.000 10.000 c l - load capacitance (uf) i k cathode current (ma) unstable * stable v ka = v ref v ka = 2v v ka = 3v figure 2 ? stability * unstable below 700a as indicated ? the unstable areas indicate loading conditi ons that may cause the device to oscillate . s s t t a a b b i i l l i i t t y y
microsemi integrated products division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 5 copyright ? 2000 rev. 1.3, 2005-02-24 www. microsemi . com lx432 low voltage adjustable precision shunt regulator p roduction d ata s heet tm ? characteristic curves 1.235 1.236 1.237 1.238 1.239 1.24 1.241 1.242 -50 0 25 50 75 100 125 t j : junction temperature (c) v ref : reference voltage (v) 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2 -50 0 25 50 75 100 125 t j : junction temperature (c) i ref : reference current(a) figure 3 ? reference voltage vs. junction temperature figure 4 ? reference current vs. junction temperature -100 0 100 200 300 400 500 600 700 800 900 -1 -0.8 -0.5 -0.3 0 0.25 0.5 0.75 1 1.25 1.5 cathode voltage (v) i k : cathode current (a) -1.2 -1 -0.8 -0.6 -0.4 -0.2 0 t j : junction temperature (c) ? v ref / ? v ka (mv/v) -50 0 25 50 75 100 125 figure 5 ? cathode current vs. cathode voltage figure 6 ? ? v ref / ? v ka vs. junction temperature c c h h a a r r a a c c t t e e r r i i s s t t i i c c s s
microsemi integrated products division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 6 copyright ? 2000 rev. 1.3, 2005-02-24 www. microsemi . com lx432 low voltage adjustable precision shunt regulator p roduction d ata s heet tm ? characteristic curves 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 -50 0 25 50 75 100 125 t j : junction temperature (c) dynamic impedance (ohm) 0 20 40 60 80 100 120 -50 0 25 50 75 100 125 t j : junction temperature (c) minimum cathode current (a) figure 7 ? dynamic impedance vs. junction temperature figure 8 ? minimum cathode current for regulation vs. junction temperature 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 -50 0 25 70 85 125 t j : junction temperature (c) off-state current (a) 0 50 100 150 200 250 300 350 10 100 1k 10k 100k frequency (hz) noise voltage (nv/sqrt(hz)) figure 9 ? off-state current vs. junction temperature figure 10 ? equivalent input noise voltage vs. frequency c c h h a a r r a a c c t t e e r r i i s s t t i i c c s s
microsemi integrated products division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 7 copyright ? 2000 rev. 1.3, 2005-02-24 www. microsemi . com lx432 low voltage adjustable precision shunt regulator p roduction d ata s heet tm ? parameter measurement information v ref input v ka i k figure 11 ? test circuit for v ka = v ref v ref input v ka r1 r2 i ref i k figure 12 ? test circuit for v ka > v ref r1 i r2 r1 1 v v v ref ref ka o + + = = ? ? ? ? ? ? input v ka i off figure 13 ? test circuit for i off m m e e a a s s u u r r e e m m e e n n t t
microsemi integrated products division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 8 copyright ? 2000 rev. 1.3, 2005-02-24 www. microsemi . com lx432 low voltage adjustable precision shunt regulator p roduction d ata s heet tm ? typical application _ + + + + + drv gnd v cc i sense v fb lx432 v out 3.3v v in 110 / 220v ac controller uc384x / lx155x figure 12 ? lx432 in a power supply isolated feedback application 500 ? 0.1f 140 ? 120 ? 1000f 0.1f 470f 0.1f 12v 3.3v 2.7v (e.g. intel i740 ? chipset) lx432 figure 13 ? lx432 in a 3.3v to 2.7v low dropout regulator application a a p p p p l l i i c c a a t t i i o o n n s s
microsemi integrated products division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 9 copyright ? 2000 rev. 1.3, 2005-02-24 www. microsemi . com lx432 low voltage adjustable precision shunt regulator p roduction d ata s heet tm ? package dimensions sc 3-pin plastic sot-23 h g f e j i a b d c note: 1. dimensions do not include mold flash or protrusions; these shall not exceed 0.155mm(.006?) on any side. lead dimension shall not include solder coverage. m illimeters i nches dim min max min max a 0.89 1.12 0.035 0.044 b 0.37 0.51 0.015 0.020 c 0.085 0.18 0.003 0.007 d 2.80 3.04 0.110 0.120 e 1.20 1.40 0.047 0.055 f 0.89 1.09 0.035 0.043 g 1.78 2.05 0.070 0.080 h 2.10 2.64 0.083 0.104 i 0.35 0.55 0.014 0.022 j 0.013 0.10 0.0005 0.0039 lp 3-pin plastic to-92 b k g n c n h a d j x x sect x-x f v note: 1. dimensions do not include mold flash or protrusions; these shall not exceed 0.155mm(.006?) on any side. lead dimension shall not include solder coverage. m illimeters i nches dim min max min max a 4.45 5.20 0.175 0.205 b 4.32 5.33 0.170 0.210 c 3.18 4.19 0.125 0.165 d 0.41 0.55 0.016 0.022 f 0.41 0.48 0.016 0.019 g 1.15 1.39 0.045 0.055 h 2.42 2.66 0.095 0.105 j 0.39 0.50 0.015 0.020 k 12.70 - 0.500 - n 2.05 2.66 0.080 0.105 v 3.43 - 0.135 - 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 division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 10 copyright ? 2000 rev. 1.3, 2005-02-24 www. microsemi . com lx432 low voltage adjustable precision shunt regulator p roduction d ata s heet tm ? 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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