description up to 1.25gbps operation 25ma peak drive current separate modulation control separate output enable for laser safety differential inputs for data 75k ? input pulldown resistor single power supply designed for use with sy88903 and sy88904 available in a tiny 10-pin (3mm) msop the sy88902 is a high speed current switch for driving a semiconductor laser diode in optical transmission applications. the output current, or modulation current i mod , is dc current controlled by i rset , current through the resistor r set . the output out is high when output enable is high. the device incorporates complementary open collector outputs with a capability of driving peak current of 25ma. the resistor r ext must be placed between /out and v cc to dissipate the worst case power. r ser is recommended to compensate for laser diode matching issues. the sy88902 utilizes the high performance bipolar asset technology. features laser diode driver wtih output enable pin configurations block diagram sy88902 final 1.25gbps gigabit ethernet 531mbps and 1062mbps fibre channel 622mbps sonet gigabit interface converter applications 1 /en d in /d in v ref r set 10 v cc out /out gnd gnd 9 8 7 6 2 3 4 5 msop k10-1 d in v cc r ext out out r ser to laser diode d in modulation control internal logic bias control en i mod v ref 40x r set v ee v cc gnd r set 1 rev.: c amendment: /1 issue date: july 2000
2 sy88902 micrel pin function v cc most positive power supply input, +5v for pecl operation. gnd ground d in , /d in these differential pecl 100k compatible inputs receive nrz data. /en this pecl 100k compatible input enables laser driver. modulation current goes to zero when asserted high. out, /out open collector outputs from the modulation buffer drive these differential current outputs. v ref voltage reference for use with r set. r set an external resistor sets up the source current for modulation i mod . d d /en out (2) /out lhlhl hlllh xxhhl notes: 1. l = low, h = high, x = don't care 2. h = i out = oma pin names truth table (1) symbol rating value unit v cc power supply voltage 0 to +7.0 v v i input voltage 0 to v cc v i o output current 25 ma t a operating temperature range 0 to +85 c t store storage temperature range 55 to +125 c p tot power dissipation 250 mw absolute maximum ratings (1) note: 1. permanent device damage may occur if absolute maximum ratings are exceeded. this is a stress rating only and functional oper ation is not implied at conditions other than those detailed in the operational sections of this data sheet. exposure to absolute maximum ratlng co nditions for extended periods may affect device reliability. symbol rating value unit v cc power supply voltage +4.5 to +5.5 v r ext resistor to dissipate power 10 to 50 ? r ser laser diode serial resistor 0 to 50 ? r set resistor to adjust current 1500 to 50,000 ? ja thermal resistance of package to ambient (2) 206 c/w c out capacitance on out + /out 2.5 typical pf operationing conditions (1) notes: 1. the voltage drop across r ext and r ser plus laser diode should not be greater than 2v. 2. still air without heatsink.
3 sy88902 micrel t a = 0 ct a = +25 ct a = +85 c symbol parameter min. typ. max. min. typ. max. min. typ. max. unit v ih input high voltage v cc -1165 v cc -880 v cc -1165 v cc -880 v cc -1165 v cc -880 mv (d in , /d in , /en) v il input low voltage v cc -1810 v cc -1475 v cc -1810 v cc -1475 v cc -1810 v cc -1475 mv (d in , /d in , /en) v ref reference voltage 3.12 3.00 2.80 v i il input low current (1) 0.5 0.5 0.5 ua (d in , /d in , /en) i ih input high current 100 100 100 ua (d in , /d in , /en) i cc supply current (2) 16 25 16 25 16 25 ma i ol output low current 500 500 500 ua (/en = high) i out modulation current 5 15 25 5 15 25 5 15 25 ma i rset modulation control 0.125 0.625 0.125 0.625 0.125 0.625 ma a rset =i out /i rset 30 38 44 30 38 44 30 38 44 notes: 1. v i = v il (min.) 2. i mod = 25ma. dc electrical characteristics gnd = 0v; v cc = +5.0v 10%; t a = 0 ? c to + 85 ? c t a = 0 ct a = +25 ct a = +85 c symbol parameter min. typ. max. min. typ. max. min. typ. max. unit conditions t pd d propagation delay 1000 500 1000 1000 ps i mod = 10ma d in - out t pd en propagation delay 1000 450 1000 1000 ps i mod = 10ma /en - out t r rise/fall time 200 200 200 ps t f (20% to 80%) i or output current ringing (2) 10 10 10 % ac electrical characteristics (1) i mod =10ma; gnd = 0v; v cc = +5v 10%; t a = 0 ? c to + 85 ? c notes: 1. r ext = r ser = 50 ? 1%, r ser connects to v cc directly without laser diode. 2. i oh = 5 to 25ma
4 sy88902 micrel application example for 3-chip set solution out v cc gnd sy88904 d in d in tx_fault tx_disable los out gbic terminal v cc out tx_out i bias en oc pecl los en md d out d out d in d in v cc gnd sy88902 sy88903 v cc gnd v cc i bias set i bias set i limit set laser module pecl r ext r ser rx_dat +rx_dat tx_disable tx_fault tx_data +tx_dat v ref r set r win v ref los v cc v ref v cc i bias fb v cc det v ref 2meg 0.1f i pin set v ref rx_los i limit set v cc los lvl
5 sy88902 micrel application example for 3-chip set solution out v cc v ee sy88905 d in d in los out gigabit ethernetterminal v cc out i bias en los en md d out d out d in d in v cc v ee sy88902 sy88903 v cc v cc v bias set i bias set laser module pecl r ext r ser rx_dat +rx_dat tx_data +tx_dat v ref r set v lvl v ref los in v ref i bias fb i pin set v ref rx_los v bb v cc i bias set v pin set gnd
6 sy88902 micrel performance curves product ordering code ordering package operating code type range sy88902kc k10-1 commercial sy88902kctr k10-1 commercial 10 20 25 30 i o (ma) i o and r set 0.0 0.0 15 5 4.0k 6.0k 8.0k 10k 2.0k r set (ohm) 12k
7 sy88902 micrel 10 lead msop (k10-1) rev. 00
8 sy88902 micrel micrel-synergy 3250 scott boulevard santa clara ca 95054 usa tel + 1 (408) 980-9191 fax + 1 (408) 914-7878 web http://www.micrel.com this information is believed to be accurate and reliable, however no responsibility is assumed by micrel for its use nor for an y infringement of patents or other rights of third parties resulting from its use. no license is granted by implication or otherwise under any patent or pat ent right of micrel inc. ? 2000 micrel incorporated
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