lx1973b p roduction d ata s heet microsemi analog mixed signal group 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 1 www. microsemi . com automotive light sensor tm ? copyright ? 2007 rev. 1.3, 2008-01-11 l l x x 1 1 9 9 7 7 3 3 b b description the lx1973b is a wide dynamic range light sensor with a very low dark current that is optimized for sensing low level light signals that typically occur under dark or darkening outdoor ambient lighting. the lx1973b has been optimized for automotive systems such as headlamp brightness control or rear view mirror contrast control. its radical (fractional exponent) response when interfaced with an 8 bit dac can detect levels down to 0.001 lux or levels as high as 500 lux. the spectral response of the integrated light sensor closely emulates the human eye so it ignores light such as infrared which emits energy but doesn?t aid vision. this eliminates the need for an infrared filter required with competitor?s light sensors. the lx1973b internal circuitry consists of a diode array with microsemi?s best eye ? processing that provides a nearly perfect photopic light wavelength response curve. the sensor output feeds into a wide dynamic range compression amplifier that provides accurate resolution over five decades of ambient light. the integrated dark current cancellation circuit facilitates accurate sensing of light below 0.01 lux. the current source output of the lx1973b can be gain scaled using one external resistor. the lx1973b is internally trimmed to an initial accuracy of 5% at room temperature and a light level of 10 lux. accuracy of 10% is maintained over the full temperature range (-40 to +85oc). important: for the most current data, consult microsemi ?s website: http://www.microsemi.com protected by us patents: 6,787,757; patents pending key features ? nearly perfect best eye ? human eye spectral response ? dark current < 0.0005 lux (@ 25c) ? 5 decades compressed output ? 10% accuracy over temperature ? scalable output voltage ? no optical filters needed applications ? auto headlamp control ? auto mirror contrast control product highlight 5v vout part lx1973b r load lx1973b response 0 1 2 3 4 0.001 0.01 0.1 1 10 100 ambient light (lux) output (volts) package order info pl plastic msop domed 8-pin pr plastic msop domed 8-pin reverse form t a ( c) rohs compliant / pb-free, nipdau finish rohs compliant / pb-free, nipdau finish -40 to 85 LX1973BIPL lx1973bipr note: available in tape & reel. append the lette rs ?tr? to the part number. (i.e. LX1973BIPL- xxxxx-tr)
lx1973b p roduction d ata s heet microsemi analog mixed signal group 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 2 www. microsemi . com automotive light sensor tm ? copyright ? 2007 rev. 1.3, 2008-01-11 l l x x 1 1 9 9 7 7 3 3 b b absolute maximum ratings v dd ................................................................................................................. -0.3 to 6 v dc snk/src (output complianc e voltage)........................................... -0.3 to v dd + 0.3v dc snk/src (maximum output cu rrent)................................................... in ternally limited operating temperature range ........................................................................ - 40 to +85c storage temperature ra nge.......................................................................... -40 to +100c rohs / pb-free peak package solder reflow temperature (40 seconds maximum e xposure).................................................................. 240c (+0, -5) notes: 1. exceeding these ratings could cause damage to the device. all voltages are with respect to ground. currents are positive into, negative out of specified terminal. thermal data pl plastic msop domed 8-pin pr plastic msop domed 8-pin reverse form thermal resistance - junction to c ase , jc 39 c/w thermal resistance - junction to a mbient , ja 206 c/w junction temperature calculation: t j = t a + (p d x ja ). the ja numbers are guidelines for the thermal performance of the device / pc-board system. all of the above assume no ambient airflow. functional pin description name pin description v dd 1 power supply voltage v ss 8 ground reference for power and signal output out 4 output current package pin out v dd nc nc out v ss nc nc nc pl p ackages (top view) 973b ywwb v ss v dd nc out nc nc nc nc pl p ackage m arking (bottom view) 973b ywwb v ss v dd nc out nc nc nc nc pr p ackage m arking (top view) v dd nc nc out v ss nc nc nc pr p ackages (bottom view) nc ? no connection msl3/240c/168 hours simplified block diagram package v dd out photopic sensor with dark current cancellation pre amplifier compression amplifier gnd lx1973b figure 1 ? simplified block diagram LX1973BIPL lx1973bipr
lx1973b p roduction d ata s heet microsemi analog mixed signal group 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 3 www. microsemi . com automotive light sensor tm ? copyright ? 2007 rev. 1.3, 2008-01-11 l l x x 1 1 9 9 7 7 3 3 b b electrical characteristics the following specifications apply over the operating ambient temperature -40 c c except where otherwise noted and the following test conditions: see note 1, v dd =5v, r out = 10k. lx1973b parameter symbol test conditions min typ max units operational voltage v dd 4.5 5.5 v supply current i dd @ 1 lux 0.22 0.27 ma power supply rejection ratio psrr v ripple = 100mv p-p , f = 10khz; c out = 0.1f 30 35 db peak spectral response pr 580 nm infrared response ) ( i ) ( i pr dd dd e v(white) = 100 lux, e v(810nm) = 14.6watt/ cm2, note 3 -5 1 5 % light to current gain g l see application section for equation saturation current i sat 520 a 1.0 lux to 0.01 lux 0.63 1.25 sec dynamic response time (to 10% settling error point) t dr 0.01 lux to 1.0 lux 0.2 0.5 sec ` dome top package output current i out(0.01) e v = 0.01 lux @ 25c, note 1,2 36 40 44 a output current i out(1.0) e v = 1.0 lux, note 1,2 114 126 139 a output current i out(10) e v = 10 lux, note 1,2 202 224 246 a output current i out(100) e v = 100 lux, note 1,2 369 410 451 a e v = 0 lux, t a = 20 c, note 4 190 380 dark current (equivalent lux) i out (dark) e v = 0 lux, t a = 50 c, note 4 700 1400 lux ` dome bottom package output current i out(0.01) e v = 0.01 lux @ 25c, note 1,2 36 40 44 a output current i out(1.0) e v = 1.0 lux, note 1,2 112 124 137 a output current i out(10) e v = 10 lux, note 1,2 201 223 245 a output current i out(100) e v = 100 lux, note 1,2 365 405 445 a e v = 0 lux, t a = 20 c, note 4 190 380 dark current (equivalent lux) i out (dark) e v = 0 lux, t a = 50 c, note 4 700 1400 lux notes: 1. the input irradiance is supplied from a point source which is a white light emitting diode (led); fairchild semiconductor p art number mv8w00. 2. see figure 2. 3. see figure 3. 4. dark current equivalent lux at 0 lux: ) 10 (146 i i el 9 4 ref out ? ? ? ? ? ? ? = for dome top package, i ref = 6446a. for dome bottom package, i ref = 6344a. e e l l e e c c t t r r i i c c a a l l s s
lx1973b p roduction d ata s heet microsemi analog mixed signal group 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 4 www. microsemi . com automotive light sensor tm ? copyright ? 2007 rev. 1.3, 2008-01-11 l l x x 1 1 9 9 7 7 3 3 b b test circuits part lx1973b out gnd v dd white led r load v out v dd figure 2 ? operational voltage measurement circuit part lx1973b out gnd v dd white led r load v out v dd 810nm figure 3 ? ir sensitivity measurement circuit application circuits part scl scd gnd adr vdd ref ain aout lx1800 dac / adc part 5v 2.5v headlamp controller brt 10k 1f 5v lx1973b lamp hi figure 4 ? typical application
lx1973b p roduction d ata s heet microsemi analog mixed signal group 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 5 www. microsemi . com automotive light sensor tm ? copyright ? 2007 rev. 1.3, 2008-01-11 l l x x 1 1 9 9 7 7 3 3 b b applications g eneral d escription the lx1973b produces an output current that is sensitive to the level of ambient light that falls onto the photosensitive area of the ic package. th e sensitivity is amplified and compressed to provide ratio metric accuracy across several decades. the sensitivity function is: () [] 0.25 e e 0.25 lux 1 i p i ambient dark ref out + = 1 lux 0.25 = 1 0.25 i ref = 126a for the domed top package i ref = 124a for the domed bottom package e dark = dark current equivalent lux expressed in lux from a white led point source. e ambient = ambient illumination expressed in lux from a white led point source.
lx1973b p roduction d ata s heet microsemi analog mixed signal group 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 6 www. microsemi . com automotive light sensor tm ? copyright ? 2007 rev. 1.3, 2008-01-11 l l x x 1 1 9 9 7 7 3 3 b b sensitivity dark current vs temp 0 50 100 150 200 250 300 350 400 450 500 0.001 0.01 0.1 1 10 100 1000 point source light (lux) output current (a) 100 1000 10000 100000 20 40 60 80 100 temperature (c) dark current (lux) normalized (pre compression) 100 lux output voltage -0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 400 600 800 1000 wavelength (nm) lx1973b human eye normalized diode response 0 1 2 3 4 5 6 02468101214 load resistor (in kilo-ohms) output voltage 4.5v 5.0v 5.5v i out vs temperature & vdd i out step response iout vs temperature @ 10 lux 195 205 215 225 -40 -20 0 20 40 60 80 100 temperature (oc) iout (ua) iout @ 4.5v iout @ 5.0v iout @ 5.5v load =10k and 0f; photo step = direct light input of 1 lux to 0.01 lux.
lx1973b p roduction d ata s heet microsemi analog mixed signal group 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 7 www. microsemi . com automotive light sensor tm ? copyright ? 2007 rev. 1.3, 2008-01-11 l l x x 1 1 9 9 7 7 3 3 b b package dimensions pl 8-pin miniature shrink outline package (msop) dome top d e e e/2 d/2 a2 l1 l b a1 seating plane e1 c a s r 0.9mm typ 1234 5 6 7 8 pin # name 1v dd 2nc 3nc 4out 5nc 6nc 7nc 8v ss m illimeters i nches dim min max min max a 1.60 1.85 0.063 0.073 a1 0.05 0.15 0.002 0.006 a2 - 1.10 - 0.043 b 0.26 0.41 0.010 0.016 c 0.13 0.23 0.005 0.009 d 2.90 3.10 0.114 0.122 e 4.75 5.05 0.187 0.199 e1 2.90 3.10 0.114 0.122 e 0.65 bsc 0.026 bsc l 0.41 0.71 0.016 0.028 l1 0.95 ref 0.037 ref s 0.525 ref 0.021 ref 3 3 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. pr 8-pin plastic msop clear package inverted dome e a e1 d e1 e b a2 a3 a1 c l1 l pin # name 1v dd 2nc 3nc 4out 5nc 6nc 7nc 8v ss 1234 5 6 7 8 m illimeters i nches dim min max min max a - 1.68 - 0.066 a1 0.05 0.15 0.002 0.006 a2 0.81 0.92 0.032 0.036 a3 0.66 0.76 0.026 0.030 b 0.26 0.41 0.010 0.016 c 0.13 0.23 0.005 0.009 d 2.90 3.10 0.114 0.122 e 4.75 5.05 0.187 0.199 e1 2.90 3.10 0.114 0.122 e 0.65 bsc 0.026 bsc e1 1.95 typ 0.077 typ l 0.41 0.71 0.016 0.028 l1 0.95 ref 0.037 ref 5 5
lx1973b p roduction d ata s heet microsemi analog mixed signal group 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 8 www. microsemi . com automotive light sensor tm ? copyright ? 2007 rev. 1.3, 2008-01-11 l l x x 1 1 9 9 7 7 3 3 b b package dimensions (continued) light footprint active area required minimum light footpri bonding / wafer area recommended light footprint pattern p2 l c recommended light foot print p1 minimum light foot print dome top package dim m illimeters i nches p1 1.8 0.070 p2 2.5 0.098 note: p2 represents a possible light footprint and its dimensions are not subject to strict tolerances. only p1 is required to be covered with light. this larger footprint is designed to ensure coverage of the device?s active area. active area required minimum light footprint bonding / wafer area recommended light footprint pattern p2 l c recommended light foot print p1 recommended pcb cutout minimum light foot print p3 dome bottom package dim m illimeters i nches p1 1.8 0.070 p2 2.5 0.098 p3 2.9 0.114 note: p2 represents a possible light footprint and its dimensions are not subject to strict tolerances. only p1 is required to be covered with light. this larger footprint is designed to ensure coverage of the device?s active area. p3 represents the minimum aperture through which the dome of the device would fit in the pcb. 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.
|
