Hệ thống truyền dữ liệu bằng ánh sáng nhìn thấy (visible light data transmission system)

bộ giáo dục đào tạo trờng đại học bách khoa hà nội [[ \\ - PHNG TH THANH H THNG TRUYN D LIU BNG NH SNG NHèN THY (VISIBLE LIGHT DATA TRANSMISSION SYSTEM) luận văn thạc sĩ kỹ thuật ngành : điện tử viễn thông NGI HNG DN KHOA HC: TS PHM NGC NAM Hà nội - 2012 LI NểI U Nhng nghiờn cu mi v thụng tin quang ang ngy cng c m rng v phỏt trin, th hin vai trũ to ln khoa hc k thut cng nh i sng ngi Hin nay, rt nhiu ng dng lnh vc trao i thụng tin bng thụng tin quang, c bit l thụng tin quang vụ tuyn Nghiờn cu, thit k, ch to mt h thng quang vi chi phớ thp m tha nhng yờu cu cn thit s gúp phn thỳc y s phỏt trin khoa hc k thut cng nh kinh t Vit Nam Mc ớch ca lun l nghiờn cu v h thng truyn d liu bng ỏnh sỏng nhỡn thy (Visible Light Data Transmission System) H thng m em nghiờn cu gm phỏt v thu quang c t cỏch vi c ly gn cho phộp truyn thụng tin tc 100 Mbps, vi photodiode cú nhy cao v cỏc linh kin vi kh nng tớch hp cỏc x lý s v tng t, h thng truyn vi hiu sut cao m cũn rt gn nh, tiờu hao ớt nng lng v cú chi phớ sn xut thp Quỏ trỡnh nghin cu v hon thnh lun em xin chõn thnh cm n TS Phm Ngc Nam (B mụn in t Tin hc - Khoa in t Vin Thụng - i hc Bỏch khoa H Ni ó trc tip hng dn tn tỡnh, chu ỏo ng thi em cng xin cm n quớ thy cụ giỏo trng i hc Bỏch khoa H Ni, cm n gia ỡnh v bn bố ó giỳp , ng viờn thi gian qua H Ni, thỏng nm 2012 Hc viờn Phựng Th Thanh LI CAM OAN Tụi xin cam oan lun "H THNG TRUYN D LIU BNG NH SNG NHèN THY" l tụi t nghiờn cu v hon thnh di s hng dn ca TS PHM NGC NAM Tụi xin chu hon ton trỏch nhim v li cam oan ny H Ni, Ngy 25 thỏng 03 nm 2012 Hc viờn Phựng Th Thanh DANH MC S , BNG BIU TT Bng Tờn bng Trang Bng 2.1 So sỏnh gia Led v Laser 10 Bng 3.1 Cỏc chun IEEE 802.3 31 Bng 3.2 Thụng s k thut ca Modem MC100CM 42 Bng 3.3 Cỏc loi b chuyn i MC100CM 43 Bng 4.1 Thụng s ca h thng thụng tin quang kh kin 49 Bng 4.2 So sỏnh cỏc ngun led trờn th trng 52 Bng 4.3 Cỏc thụng s k thut ca MC 2042 [23] 65 Bng 4.4 Cỏc giỏ tr linh kin mch 66 Bng 5.2 72 so sỏnh cỏc photodetector DANH MC HèNH V TT Hỡnh Tờn hỡnh Trang Hỡnh 1-1 The visible spectrum: Ph ca ỏnh Hỡnh 2-1 Cỏc vựng bc súng ca ỏnh sỏng Hỡnh 2-2 Búng ốn si t Hỡnh 2-3 ốn compact Hỡnh 2-4 ốn hunh quang 6 Hỡnh 2-5 Cỏc loi ốn led thc t 7 Hỡnh 2-6 ốn LED chiu sỏng Hỡnh 2-7 ng dng truyn thụng tin nh Hỡnh 2-8 ng dng truyn thụng tin trờn mỏy bay 10 Hỡnh 2-9 K hoch trin khai ng dng VLC 11 Hỡnh 2-10 Led ca hóng Luxeon 12 Hỡnh 2-11 S hp th khớ quyn ca cỏc bc song 13 Hỡnh 2-12 On Off Keying 13 14 Hỡnh 3-1 15 Hỡnh 3-2 K thut FTTH 16 Cỏc k thut liờn quan n FTTH 18 16 Hỡnh 3-3 17 Hỡnh 3-4 Cu hỡnh mng Bus 21 Cu hỡnh mng Star 23 18 Hỡnh 3-5 19 Hỡnh 3-6 Cu hỡnh mng Ring 24 Cu hỡnh dng li 24 20 Hỡnh 3-7 21 Hỡnh 3-8 Cu hỡnh mng Star Bus 25 Cỏc chun IEEE 802 khụng dõy 38 22 Hỡnh 3-9 23 Modem Tp-Link MC100CM 41 Hỡnh 3-10 12 14 Modem Planet 10/100 Base Px Smart Media Conver ter 44 24 Hỡnh 3-11 Chun kt ni RJ45 25 Hỡnh 3-12 Dng súng tớn hiu Ethernet 10 Mbps qua cỏp cat 45 26 Hỡnh 3-13 Ph tn tớn hiu Ethernet 100 Mbps 46 45 27 Hỡnh 3-14 Vớ d v tớn hiu trc v sau mó hoỏ 28 Hỡnh 3-15 Vớ d v tớn hiu cui cựng sau mó hoỏ MLT-3 47 29 Hỡnh 4-1 30 Hỡnh 4-2 S dng thu kớnh cho h thng VLC 51 Mt Webcam dựng lm thu kớnh 51 31 Hỡnh 4-3 32 Hỡnh 4-4 S mch phỏt 51 Mch shunt module phỏt dựng MAX3967 54 33 Hỡnh 4-5 34 Hỡnh 4-6 S nguyờn lý ca module phỏt dựng MAX3967A 54 Ngun V dựng 7805 56 35 Hỡnh 4-7 36 Hỡnh 4-8 Hỡnh minh MAX3967A 57 Cu to bờn ca MAX3967A 57 37 Hỡnh 4-9 Cỏch mc u vo MAX3967A 58 47 38 Hỡnh 4-10 Mch in mt trờn 39 Hỡnh 4-11 Mch in mt di 59 40 Hỡnh 4-12 Hỡnh minh mch thc t 41 Hỡnh 4-13 Mch nguyờn lý s dng MC2042 60 42 Hỡnh 4-14 Mch ngun V 43 Hỡnh 4-15 MC2042 dng chõn QSOP16 62 44 Hỡnh 4-16 Cỏc bờn MC2042 45 Hỡnh 4-17 Biu dũng iu khin LED theo nhit 63 60 61 62 65 46 Hỡnh 4-18 Mch in mt trờn 47 Hỡnh 4-19 Mch in mt di 67 48 Hỡnh 4-20 Hỡnh minh mch thc t 68 49 Hỡnh 4-21 Biu din hỡnh hc thit lp ỏnh sỏng truyn n PIN 69 50 Hỡnh 5-1 S cỏc mt modul thu quang in hỡnh 70 51 Hỡnh 5-2 ỏp ng quang ca OPF430 72 52 Hỡnh 5-3 Cu hỡnh khuch i chuyn tr khỏng c bn 73 53 Hỡnh 5-4 S mch thu 74 54 Hỡnh 5-5 Mch in module thu 75 68 M U Ngy nhng ng dng liờn quan n thụng tin quang vụ tuyn ang rt phỏt trin trờn th gii, c bit l h thng thụng tin quang kh kin bi d trin khai, lp t phũng Cỏc h thng Internet cỏp ng trc õy ó li thi thi i ngy tc gii hn t ti a l 100 Mbps, suy hao ln, i dõy phc H thng thụng tin quang kh kin s dng LEDs chiu sỏng th hin nhiu u im so vi vic s dng cỏp ng v hn s mang li nhiu ng dng cụng tỏc nghiờn cu khoa hc cng nh cỏc ng dng khỏc i sng Vi kh nng cú th truyn tc t hng trm Mbps n hng Gbps, ng dng ca h thng s gii quyt c nhiu vic trin khai mng gia ỡnh vi tc cao v chi phớ thp m li gn nh, khụng phi i dõy phc v.v S kt hp ca driver LED MC2042 ca hóng Motorola v cỏc IC ca MAXIM khụng nhng gii quyt c bi toỏn k thut m cũn gii quyt c bi toỏn kinh t Mt sn phm vi tin cy cao cựng chi phớ sn xut thp luụn phự hp vi iu kin kinh t Vit Nam hin Ni dung Lun gm chng, ú : Chng I: Gii thiu Chng II: Tỡm hiu v h thng thụng tin quang kh kin v ngun sỏng LED Chng III: Tng quan v mng bng rng Chng IV: Trỡnh by cỏc bc thit k module phỏt s dng LED cho h thng thụng tin quang kh kin c ly gn Chng V: Trỡnh by cỏc bc thit k module thu s dng PIN cho h thng thụng tin quang kh kin MC LC Trang Trang ph bỡa Li núi u Túm tt lun Dang mc cỏc bng Danh mc cỏc hỡnh v, th Danh mc cỏc t vit tt CHNG I: GII THIU 1.1 VLDT (Visible light Data transmission) l gỡ? 1.2 ng dng 1.3 Vỡ nghiờn cu VLDT 1.4 Ni dung nghiờn cu CHNG II: TNG QUAN V H THNG THễNG TIN QUANG KH KIN 2.1 Thụng tin quang kh kin 2.1.1 H thng thụng tin quang kh kin l gỡ 2.1.2 u im chớnh 2.2 Xu th phỏt trin ca cỏc ngun sỏng 2.2.1 Th h mt ốn si t 2.2.2 Th h hai ốn hunh quang 2.2.3 Th h ba ốn LED 2.3 LED chiu sỏng v ng dng h thng thụng tin quang kh kin 2.4 K hoch trin khai ti 2.5 Mt s c tớnh c bn ca LED v LED chiu sỏng 2.6 So sỏnh LED vi LD h thng thụng tin quang 10 2.6.1 V bn cht 10 2.6.2 V hot ng 11 2.7 La chn loi LED phự hp 12 2.7.1 Cỏc phng ỏn la chn 12 2.7.2 Phng thc truyn dn d liu ca LED 13 CHNG III: TNG QUAN V MNG BNG RNG 3.1 Cỏc chun IEEE cho mng truyn thụng 15 3.1.1 ISDN 15 3.1.2 ADSL 16 3.1.3 FTTH v cỏc k thut liờn quan 16 3.1.3.1 FTTH l gỡ? 16 3.1.3.2 Cỏc k thut liờn quan 17 3.2 Mt s cu hỡnh mng 20 3.2.1 Cu hỡnh mng BUS 21 3.2.1.1 Gi tớn hiu 22 3.2.1.2 Di tớn hiu 22 3.2.1.3 Terminator 22 3.2.2 Cu hỡnh mng Star 22 3.2.3 Cu hỡnh mng Ring 23 3.2.4 Cu hỡnh mng li (Mesh) 24 3.2.5 Cu hỡnh mng kt hp 24 3.3 Cỏc chun IEEE cho mng truyn thụng 25 3.3.1 IEEE 802 31 3.3.2 IEEE 802 34 3.3.3 IEEE 802 11 34 3.3.4 IEEE 802 16 38 3.3.5 IEEE 802 20 40 3.3.5.1 Tng quan 40 3.3.5.2 c im k thut 40 3.4 Tỡm hiu mt s b modem quang h thng Internet theo chun 41 Ethernet 3.4.1 Modem TPlink MC100CM 41 3.4.1.1 Gii thiu 41 3.4.1.2 c im 42 3.4.2 Modem Planet 10/100 Base Fx Smart media converter 43 3.5 Chun J45 45 3.5.1 Gii thiu 45 3.5.2 Cỏch mó húa d liu truyn qua cỏp xon loi 45 3.6 Chun u vo PECL 48 CHNG 4: THIT K MODULE PHT CHO H THNG THễNG TIN QUANG KH KIN 4.1 Yờu cu h thng 49 4.2 Phõn tớch thit k Module phỏt quang 50 4.3 Thit k h thng phỏt 51 4.3.1 Ngun sỏng 52 4.3.2 Mch iu khin LED 53 4.3.2.1 Mch iu khin s dng IC iu khin LED MAXIM3967A 53 4.3.2.2 Mch iu khin s dng IC iu khin LED MC 2042 61 4.4 Thit k h thng quang hc 68 CHNG V: THIT K MODULE PHT CHO H THNG THễNG TIN QUANG KH BIN 5.1 Thit k module thu quang 70 5.1.1 Photodetector 70 5.1.2 Khuch i chuyn tr khỏng 72 5.1.3 Tớnh toỏn giỏ tr cỏc linh kin 73 5.2 Tớch hp h thng quang vi MC100CM cho h thng VLC c ly gn 75 KT LUN 76 TI LIU THAM KHO 78 Visible Light Data Transmission System 5.1.3 Tớnh toỏn giỏ tr cỏc linh kin 70 5.2 Tớch hp h thng quang vi MC100CM cho h thng VLC c ly gn 72 KT LUN 73 TI LIU THAM KHO 74 Phựng Th Thanh CA100080 79 19-3252; Rev 0; 5/04 270Mbps SFP LED Driver Features The MAX3967 is a programmable LED driver for fiber optic transmitters operating at data rates up to 270Mbps The circuit contains a high-speed current driver with programmable temperature coefficient (tempco), adjustments for LED prebias voltage, and a disable feature The circuit accepts PECL data inputs, and operates from a single +2.97V to +5.5V power supply TX_DISABLE for SFP Compatibility The SFP LED driver can switch up to 100mA into typical high-speed light-emitting diodes As temperature increases, the devices modulation current increases with a tempco that is programmable from 2500ppm/C to 12,000ppm/C The modulation current is programmed with a single external resistor Programmable LED Prebias Voltage The MAX3967s LED prebias voltage is programmable from 400mV to 925mV The prebias circuit produces peaking current, which improves the LED switching speed Complementary current outputs help to maintain a constant supply current, reducing EMI and supply noise generated by the transmitter module The MAX3967 is available in die form, or in a 4mm x 4mm, 24-pin thin QFN package Single +2.97V to +5.5V Power Supply Adjustable Temperature Compensation Adjustable Modulation Current Complementary Output Reduces Supply Noise Available in 24-Pin QFN or Die Ordering Information PART MAX3967ETG MAX3967E/D TEMP RANGE -40C to +85C -40C to +85C PIN-PACKAGE 24 Thin QFN Dice* *Dice are tested and guaranteed only at TA = +25C Applications Pin Configuration VEE TX_DISABLE IN+ IN- VCC Fast Ethernet/FDDI TCMIN Multimode LED Transmitters 24 23 22 21 20 19 TOP VIEW 155Mbps LAN ATM Transceivers ESCON Receivers SFP Transceivers TCNOM 18 MODSET TC 17 MON PB1 16 N.C MAX3967 PB2 15 VCC PB3 14 VCCOUT VEEOUT 13 VCCOUT 10 11 12 OUT+ OUT- OUT- N.C VEEOUT OUT+ Typical Operating Circuits appear at end of data sheet THIN QFN (4mm x 4mm) THE EXPOSED PAD MUST BE CONNECTED TO GROUND FOR PROPER THERMAL AND ELECTRICAL PERFORMANCE Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxims website at www.maxim-ic.com MAX3967 General Description MAX3967 270Mbps SFP LED Driver ABSOLUTE MAXIMUM RATINGS Supply Voltage at VCC, VCCOUT (VEE, VEEOUT = 0V) -0.5V to +7V Current into OUT+, OUT- -40mA to +160mA Differential Output Voltage (OUT+ to OUT-) -3.3V to +3.3V Voltage at PB1, PB2, PB3, IN+, IN-, OUT+, OUT-, TX_DISABLE -0.5V to (VCC + 0.5V) Voltage at TCMIN, TCNOM, TC, MODSET, MON -0.5V to +2V Continuous Power Dissipation (TA = +85C) 24-Lead Thin QFN (derate 20.8mW/C above +85C) 1354mW Operating Junction Temperature Range -40C to +150C Die Attach Temperature +400C Storage Temperature Range .-50C to +150C Lead Temperature (soldering, 10s) +300C Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied Exposure to absolute maximum rating conditions for extended periods may affect device reliability DC ELECTRICAL CHARACTERISTICS (Load as specified in Figure 1; VCC = +2.97V to +5.5V (at the VCC pins); VEE, VEEOUT = 0V; TA = -40C to +85C, unless otherwise noted Temperature coefficients are referenced to TA = +25C Typical values are at VCC = +3.3V, TA = +25C, unless otherwise noted Dice are tested at TA = +25C only.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS V Data Input High Voltage Referenced to VCC, DC-coupled input -1.165 -0.880 Data Input Low Voltage Referenced to VCC, DC-coupled input -1.810 -1.475 V 39 mA +50 àA Supply Current ICC (Note1) 30 Input Current at IN+ or IN- -50 RMODSET = 698 (Note 2) Modulation Current RMODSET = 3.0k (Note 3) TA = -40C 110 TA = +25C 124 TA = +85C 139 TA = -40C 14 TA = +25C 18 TA = +85C Prebias Voltage 22 (Note 3) 66.0 75 84.5 PB1, PB2, PB3 = (open, open, open) 0.368 0.400 0.451 PB1, PB2, PB3 = (VEE, VEE, open) 0.575 0.625 0.696 PB1, PB2, PB3 = (VEE, VEE, VEE) 0.848 0.925 1.026 Maximum tempco (TC open) Temperature Coefficient of Modulation Current Prebias Resistor VIH TX_DISABLE Low VIL Monitor Gain Nominal tempco (TC shorted to TCNOM) 3600 2500 Resistance to VEE (Note 4) TX_DISABLE High ppm/C 66 78 90 50 65 100 k 2.0 IMON / IMODSET, VMON < 1.1V, RMODSET = 1k, TC = TCMIN V 12,000 Minimum tempco (TC shorted to TCMIN) RPREBIAS TX_DISABLE Resistance mA 0.92 V 0.8 V 1.08 A/A Note 1: RMODSET = 1k Excludes IOUT+ and IOUT-, TX_DISABLE high or low Note 2: TC connected to TCMIN Note 3: VCC = +3.3V, VLED = 1.55V, prebias voltage programmed at 0.625V (nominal), TA = +25C RMODSET = 1k, (programs approximately 80mA), TC connected to TCNOM Note 4: The TX_DISABLE pin is internally pulled low The driver is enabled when TX_DISABLE is left open _ 270Mbps SFP LED Driver (Load as specified in Figure 1, unless otherwise noted VCC = +2.97V to +5.5V (at the VCC pins), RMODSET = 1k, TA = -40C to +85C Input data edge speed = 1ns (typ), PB1 = PB2 = VEE, PB3 = open Typical values are at VCC = +3.3V, TC connected to TCNOM, TA = +25C.) (Note 5) PARAMETER SYMBOL CONDITIONS MIN Data Input Range Differential input 500 Output-Current Edge Speed 20% to 80%, input is a 12.5MHz square wave 300 Output-Current Pulse-Width Correction (PWC) Note Output-Current Data-Dependent Jitter DJ Random Jitter RJ TYP MAX UNITS 2400 mVP-P 615 1230 ps -80 266Mbps (Note 7) 140 155Mbps (Note 8) 150 ps 250 psP-P psRMS TX_DISABLE Assert Time t_off Time from rising edge of TX_DISABLE to output at 10% of steady state TX_DISABLE Negate Time t_on Time from rising edge of TX_DISABLE to output at 90% of steady state 0.01 0.5 às Power-On Time t_init Time from VCC > 2.97V to output at 90% of steady state 0.1 ms Note 5: Note 6: Note 7: Note 8: 0.01 0.5 às AC characteristics are guaranteed by design and characterization PWC = (widthCURRENT ON - widthCURRENT OFF) / Test pattern is a K28.5 (0011 1110 1011 0000 0101) transmitted at 266Mbps Test pattern is equivanlent to a 213 - PRBS containing 72 consecutive zeros or 72 consecutive ones VCC VCC VLED 1.55V L1 VCC VPREBIAS FERRITE BEAD OSCILLOSCOPE 0.1àF OUT- OUT+ OUT- OUT+ OUT- 50 MAX3967 MAX3967 MAX3967 0.1àF 50 SWITCHING DIODE OUT+ DC ELECTRICAL LOAD (EXCEPT PREBIAS VOLTAGE) DC ELECTRICAL LOAD FOR PREBIAS VOLTAGE AC ELECTRICAL LOAD Figure MAX3967 Output Test Loads _ MAX3967 AC ELECTRICAL CHARACTERISTICS Typical Operating Characteristics (MAX3967ETG in Maxim evaluation board, VCC = +3.3V, PB1 = PB2 = VEE, PB3 = open, TC connected to TCNOM, RMODSET = 1k, TA = +25C, unless otherwise noted.) MODULATION CURRENT vs TEMPERATURE VCC = 5.0V 34 32 30 28 VCC = 3.3V 26 24 NOMINAL TEMPCO 100 MINIMUM TEMPCO 80 60 40 MAXIMUM TEMPCO 120 MODULATION CURRENT (mA) SUPPLY CURRENT (mA) 36 120 MAX3967 toc02 EXCLUDES CURRENT INTO OUT+ AND OUT- 38 MODULATION CURRENT (mA) MAX3967 toc01 40 DIE MODULATION CURRENT vs TEMPERATURE 20 MINIMUM TEMPCO 100 80 60 MAXIMUM TEMPCO 40 20 NOMINALTEMPCO 22 20 0 -40 -40 -30 -20 -10 10 20 30 40 50 60 70 80 90 AMBIENT TEMPERATURE (C) 20 40 60 80 20 80 100 120 140 MINIMUM TEMPCO MAXIMUM TEMPCO MAX3967 toc06 100 200 MODULATION CURRENT (mA) MAX3967 toc05 NOMINALTEMPCO MODULATION CURRENT (mA) 60 DIE MODULATION CURRENT vs RMODSET 200 MAX3967 toc04 10,000 40 JUNCTION TEMPERATURE (C) MODULATION CURRENT vs RMODSET 100 MINIMUM TEMPCO NOMINALTEMPCO MAXIMUM TEMPCO 1000 10 10 100 10 500 1k 10k 500 1k 8k RTC (k) RMODSET () RMODSET () EYE DIAGRAM (ELECTRICAL) 266Mbps EYE DIAGRAM (OPTICAL) 155Mbps EYE DIAGRAM (OPTICAL) 155Mbps MAX3967 toc07 500ps/div PATTERN = 231 - PRBS -20 AMBIENT TEMPERATURE (C) MODULATION CURRENT TEMPCO vs RTC 100,000 MAX3967 toc03 SUPPLY CURRENT vs TEMPERATURE MODULATION CURRENT TEMPCO (ppm/C) MAX3967 270Mbps SFP LED Driver MAX3967 toc08 1ns/div RECEIVER BW = 200MHz, VCC = 2.97V, TA = +85C, PAVE = -17.1dBm, PATTERN = 231 - PRBS MAX3967 toc09 1ns/div RECEIVER BW = 200MHz, VCC = 5.5V, TA = -40C, PAVE = -15.8dBm, PATTERN = 231 - PRBS _ 270Mbps SFP LED Driver RANDOM JITTER vs TEMPERATURE EYE DIAGRAM (OPTICAL) 155Mbps MAX3967 toc10 MAX3967 toc11 MAX3967 toc12 EYE DIAGRAM (OPTICAL) 155Mbps RANDOM JITTER (psRMS) VCC = 3.3V MAXIMUM TEMPCO VCC = 5.0V MINIMUM TEMPCO 0 1ns/div 1ns/div RECEIVER BW = 200MHz, VCC = 5.5V, TA = +85C, PAVE = -17.1dBm, PATTERN = 231 - PRBS RECEIVER BW = 200MHz, VCC = 2.97V, TA = -40C, PAVE = -15.8dBm, PATTERN = 231 - PRBS TX_DISABLE NEGATE TIME 20 30 40 50 60 70 80 90 AMBIENT TEMPERATURE (C) TX_DISABLE ASSERT TIME MAX3967 toc13 LED OUTPUT 10 MAX3967 toc14 LED OUTPUT t_off t_on TX_DISABLE TX_DISABLE 4ns/div 4ns/div _ MAX3967 Typical Operating Characteristics (continued) (MAX3967ETG in Maxim evaluation board, VCC = 3.3V, PB1 = PB2 = VEE, PB3 = open, TC connected to TCNOM, RMODSET = 1k, TA = +25C, unless otherwise noted.) 270Mbps SFP LED Driver MAX3967 Pin Description PIN NAME FUNCTION TCNOM TC 3, 4, PB1, PB2, PB3 6, VEEOUT 8, OUT+ Current Output Pins 10, 11 OUT- Complementary Current Output Pins 12, 16 N.C Not Connected 13, 14 VCCOUT 15, 19 VCC Provides Current to the Internal Amplifiers 17 MON The Current Sourced from the MON Pin is Proportional to the Modulator Current 18 MODSET 20 IN- Inverting Data Input 21 IN+ Noninverting Data Input 22 TX_DISABLE 23 VEE 24 TCMIN Shorting TC to TCNOM provides a modulation tempco of approximately 3600 ppm/C A resistor (RTC) connected between the TC and TCMIN pins sets the tempco of the modulation current Leaving RTC unconnected provides the maximum tempco Programs the Prebias Voltage at the OUT+ Pin (Table 1) Ground for the Output-Current Drivers Supply Connection for the Output-Current Drivers A Resistor from MODSET to VEE Programs the LED Modulation Current Transmit Disable When high, the current at the OUT+ pins is in the low state The transmitter is enabled when TX_DISABLE is open Ground for internal amplifiers Shorting TC to TCMIN provides the minimum modulation-current tempco Detailed Description The MAX3967 provides a flexible current drive for the modulation of fiber optic light-emitting diodes (LEDs) The circuit is designed to be used with +3.3V or +5V power supplies The IC provides up to 100mA of modulation current An adjustable prebias current source sets the LED prebias voltage An integrated resistor provides passive peaking and optical pulse-width compensation Figure shows a block diagram of the MAX3967, which comprises a reference-voltage generator, modulationcurrent generator, input buffer with disable, prebiascurrent generator, main output driver, complementary output driver, and LED-compensation network Temperature Compensation The reference-voltage generator circuit provides two voltage sources that create modulation-current temperature compensation A positive modulation-current temperature coefficient (tempco) is useful to compensate for the temperature characteristics of typical fiber optic LEDs The first source has a temperature-stable output The second source has a temperature-increasing output with a tempco of approximately 12,000ppm/C (relative to +25C) A resistor-divider between the two reference generators programs the modulation-current tempco For maximum modulation-current tempco, leave the TC pin disconnected For a tempco of approximately 3600ppm/C, connect TC to TCNOM To obtain the minimum tempco, connect TCMIN to TC Intermediate tempco values can be programmed by connecting an external resistor (RTC) between TCMIN and TC Input Buffer The inputs are connected to the PECL-compatible differential input buffer If left unconnected, IN+ is internally pulled to a PECL low and IN- is pulled to a PECL high, causing low current at OUT+ The input impedance of IN+ and IN- is approximately 50k _ 270Mbps SFP LED Driver MAX3967 TX_DISABLE VCCOUT OUTMAX3967 INPUT BUFFER IN+ COMPLEMENTARY OUTPUT 24X IN- MODULATIONCURRENT GENERATOR RPREBIAS 78 MAIN OUTPUT 24X OUT+ GAIN 4X VCC 35 REFERENCE-VOLTAGE GENERATOR 12pF 1.2V V TEMP TCMIN TCNOM TC PREBIAS-CURRENT GENERATOR 50 MODSET RMODSET MON PB1 PB2 PB3 Figure Functional Diagram Modulation-Current Generator Prebias Current Generator The modulation-current generator circuit provides control of the modulation-current amplitude This amplitude is determined by the voltage at the MODSET pin and external resistor RMODSET Do not connect bypass capacitors at the MODSET pin Capacitance at this pin increases high-frequency output noise The MON pin provides an optional modulation-current monitor The current sourced from the MON pin is 1/96 of the modulation current If used, the pin should be connected to VEE through a resistor The resistance must be chosen so the voltage on MON does not exceed 1.1V If not used, leave MON open A prebias voltage (V PREBIAS) can be applied to the LED to improve switching speed The prebias current generator creates a current that flows through the 78 prebias resistor in the output stage, creating a prebias voltage The prebias voltage can be adjusted by selectively connecting pins PB1, PB2, and PB3 to VEE Table describes the functions of PB1, PB2, and PB3 Output Current Drivers The modulation-current reference is switched and amplified by the output stages LED package lead inductance causes ringing and overshoot, which can be compensated with an RC filter network The MAX3967 includes 35 and 12pF of inter- _ MAX3967 270Mbps SFP LED Driver Table LED Prebias Voltage PB1 PB2 PB3 PREBIAS (V) Open Open Open 0.400 VEE Open Open 0.475 Open VEE Open 0.550 VEE VEE Open 0.625 Open Open VEE 0.700 VEE Open VEE 0.775 Open VEE VEE 0.850 VEE VEE VEE 0.925 nal compensation The compensation network can be optimized by adding additional components between VCCOUT and OUT+ The MAX3967 includes a complementary output driver, which is switched 180 out of phase with the main output This configuration helps to maintain constant current flow from the voltage supply, reducing noise and EMI A large diode and a resistor are connected in series with the negative output (OUT-) to emulate the LED load at OUT+ Peaking Current The prebias resistor provides peaking current to improve the LED switching speed The peaking magnitude is given by the following equation: V -V IPEAK = LED PREBIAS 78 The peaking amplitude is equal for rising and falling data transitions Design Procedure See the Modulation-Current Tempco vs RTC graph in the Typical Operating Characteristics to program a custom tempco From the graph, determine the appropriate resistor and connect it between TCMIN and TC For example, if an LED requires a 5000ppm/C tempco, choose RTC of 8.3k Program the Modulation Current Determine the required modulation current at TA = +25C Then select the appropriate value of RMODSET from the Modulation Current vs RMODSET graph in the Typical Operating Characteristics For example, to program 75mA modulation current, the graph indicates an RMODSET value of 750 for maximum tempco (12,000ppm/C) and 1k for nominal tempco (3600ppm/C) By interpolation, choose an RMODSET of 792 for a tempco of 5000ppm/C Program Prebias Voltage Determine the LED prebias voltage that produces an acceptable trade-off between peaking current and extinction ratio See Table for PB1, PB2, and PB3 settings Layout Considerations For optimum performance, total load inductance should not exceed 10nH Load inductance includes LED inductance, LED package lead inductance, and circuitboard traces Keep the connections between the MAX3967 OUT pins and the LED as short as possible to minimize inductance Chip-and-wire (hybrid) technology reduces package inductance significantly, and provides the best possible performance Use good high-frequency layout techniques and a multilayer board with an uninterrupted ground plane Power supplies should be capacitively bypassed to the ground plane with surface-mount capacitors located near the power-supply pins Select an LED For best performance, select a high-efficiency, lowinductance LED LED inductance causes large voltage swings and ringing Program the Modulation-Current Tempco Select a modulation-current tempco that provides nearly constant LED output power as temperature varies For the minimum tempco, connect TCMIN to the TC pin For a tempco of approximately 3600ppm/C, connect TC to TCNOM and leave TCMIN unconnected For the maximum tempco, leave TCMIN, TCNOM, and TC unconnected _ 270Mbps SFP LED Driver Exposed-Pad Package The exposed pad on the 24-pin QFN provides a very low thermal resistance path for heat removal from the IC MAX3967 PECL OUTPUT IN+ Chip Information TRANSISTOR COUNT: 327 SUBSTRATE CONNECTED TO VEE PROCESS: BIPOLAR DIE THICKNESS: 15 mils 50 VCC - 2V VCC R1 MAX3967 RF OR NON-PECL OUTPUT IN+ R2 VCC R1 R2 3.3 82 130 5.0 68 180 SINGLE-ENDED TERMINATION IS SHOWN IN- SHOULD BE TERMINATED SIMILARLY Figure Input Terminations Applications Information Wire-Bonding Die The MAX3967 utilizes gold metalization, which provides high reliability Make connections to the die with gold wire only, using ball-bonding techniques Use caution if attempting wedge-bonding Pad size is mils x mils (100àm) Die thickness is typically 15 mils (375àm) _ MAX3967 Input Terminations 270Mbps SFP LED Driver MAX3967 Typical Operating Circuits SFP TRANSMITTER +3.3V FERRITE BEAD 10k VCC DISABLE +3.3V 82 VCCOUT TX_DISABLE OUT- +3.3V OUT+ 82 MAX3967 CIN IN+ DIFFERENTIAL DATA VEEOUT IN- CIN PB1 120 VEE PB2 PB3 TCMIN TCNOM TC MODSET 120 RMODSET SFP TRANSMITTER WITH DIGITAL MONITOR +3.3V FERRITE BEAD 10k VCC DISABLE +3.3V 82 VCCOUT TX_DISABLE OUT- +3.3V OUT+ 82 MAX3967 CIN IN+ DIFFERENTIAL DATA VEEOUT IN- CIN 120 VEE MON 120 PB1 PB2 PB3 TCMIN TCNOM TC MODSET RMODSET DIAGNOSTIC IC RMON 10 270Mbps SFP LED Driver SFF TRANSMITTER WITH DISABLE VCC VCC DISABLE PECL DATA FERRITE BEAD VCCOUT TX_DISABLE OUT- IN+ OUT+ MAX3967 IN- VEEOUT MON VEE PB1 PB2 TC PB3 TCMIN TCNOM MODSET RMODSET RTC* *OPTIONAL COMPONENT SFF TRANSMITTER WITHOUT DISABLE VCC VCC FERRITE BEAD VCCOUT TX_DISABLE PECL DATA OUT- OUT+ IN+ MAX3967 IN- VEEOUT MON PB1 VEE PB2 PB3 TCMIN TCNOM TC MODSET RMODSET 11 MAX3967 Typical Operating Circuits (continued) MAX3967 270Mbps SFP LED Driver Chip Topography TX_DISABLE VEE TCMIN TCNOM 1 3 PB1 4 PB2 5 PB3 6 VEEOUT 7 VEEOUT 8 12 21 21 20 20 IN- 19 19 2 TC (0, 0) 22 22 IN+ 18 18 17 17 16 16 VCC MODSET MON 1.83mm (72.0 mils) 15 15 9 10 10 11 11 12 12 OUT+ OUT+ OUT- OUT1.17mm (46.1 mils) VCC 14 14 VCCOUT 13 13 VCCOUT Pad Coordinates COORDINATES (àm) PAD NUMBER PAD NAME BP1 TCMIN BP2 TCNOM 1268 BP3 TC 1060 BP4 PB1 876 BP5 PB2 744 BP6 PB3 560 BP7 VEEOUT 116 BP8 VEEOUT 0 BP9 OUT+ 180 BP10 OUT+ 296 BP11 OUT- 480 BP12 OUT- 596 BP13 VCCOUT 804 BP14 VCCOUT 804 124 BP15 VCC 804 528 BP16 MON 804 1032 BP17 MODSET 804 1240 BP18 VCC 804 1464 BP19 IN- 624 1464 X Y 1464 BP20 IN+ 492 1464 BP21 TX_DISABLE 308 1464 BP22 VEE 176 1464 270Mbps SFP LED Driver 24L QFN THIN.EPS PACKAGE OUTLINE 12, 16, 20, 24L THIN QFN, 4x4x0.8mm 21-0139 PART PACKAGE TYPE MAX3967ETG 24 thin QFN (4mm x 4mm x 0.8mm) C PACKAGE CODE T2444-4 13 MAX3967 Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications For the latest package outline information, go to www.maxim-ic.com/packages.) MAX3967 270Mbps SFP LED Driver Package Information(continued) (The package drawing(s) in this data sheet may not reflect the most current specifications For the latest package outline information, go to www.maxim-ic.com/packages.) PACKAGE OUTLINE 12, 16, 20, 24L THIN QFN, 4x4x0.8mm 21-0139 C 2 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product No circuit patent licenses are implied Maxim reserves the right to change the circuitry and specifications without notice at any time 14 Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 â 2004 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products ... bày khái quát chung hệ thống truyền liệu ánh sáng nhìn thấy Ưu điểm hệ thống VLDT 1.1 VLDT (Visible light Data Transmission) gì? Ánh sáng mắt người nhìn thấy gọi Ánh sáng nhìn thấy, có bước sóng... công nghệ truyền liệu không dây mới, tận dụng nguồn ánh sáng LED từ đèn, từ hình nhằm tiết kiệm lượng Ánh sáng đèn LED loại ánh sáng nhìn thấy Được ứng dụng truyền liệu dựa hệ thống ánh sáng đèn... Light Data Transmission System CHƯƠNG II TỔNG QUAN VỀ HỆ THỐNG THÔNG TIN QUANG KHẢ KIẾN Chương giới thiệu tổng quan hệ thống thống tin quang khả kiến (Visible Light Communication) hệ nguồn chiếu sáng