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never stop thinking. preliminary data sheet, may 2001 ics for communications foa2322a 3.2 gbit/s laser driver ic for telecom and datacom applications
edition 2001-05 published by infineon technologies ag, st.-martin-strasse 53, d-81541 mnchen, germany ? infineon technologies ag 2001. all rights reserved. attention please! the information herein is given to describe certain components and shall not be considered as warranted characteristics. terms of delivery and rights to technical change reserved. we hereby disclaim any and all warranties, including but not limited to warranties of non-infringement, regarding circuits, descriptions and charts stated herein. infineon technologies is an approved cecc manufacturer. information for further information on technology, delivery terms and conditions and prices please contact your nearest infineon technologies office in germany or our infineon technologies representatives worldwide. warnings due to technical requirements components may contain dangerous substances. for information on the types in question please contact your nearest infineon technologies office. infineon technologies components may only be used in life-support devices or systems with the express written approval of infineon technologies, if a failure of such components can reasonably be expected to cause the failure of that life-support device or system, or to affect the safety or effectiveness of that device or system. life support devices or systems are intended to be implanted in the human body, or to support and/or maintain and sustain and/or protect human life. if they fail, it is reasonable to assume that the health of the user or other persons may be endangered.
preliminary data sheet, may 2001 never stop thinking. ics for communications foa2322a 3.2 gbit/s laser driver ic for telecom and datacom applications
for questions on technology, delivery and prices please contact the infineon technologies offices in germany or the infineon technologies companies and representatives worldwide: see our webpage at http://www.infineon.com foa2322a revision history: 2001-05 previous version: page subjects (major changes since last revision)
foa2322a table of contents page preliminary data sheet 1 2001-05 1 overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1 features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.2 applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.3 technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.4 general . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2 electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.1 absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.2 general operating conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.3 characteristics and operating conditions . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.4 typical characteristics of temperature compensation (mode 1) . . . . . . . 14 2.4.1 modulation current swing versus r mod , r tc , junction temperature and supply voltage / high current drive . . . . . . 14 2.4.2 modulation current swing versus r mod , r tc , junction temperature and supply voltage / low current drive . . . . . . 16 2.5 principle of modulation current control by using a pilot signal (mode 2) 18 2.6 data / clock input stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 2.7 timing of clock and data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 2.8 laser and v cc supervising circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 2.9 input signal monitoring and hardware alarm (consideration in absence of laser fault) . . . . . . . . . . . . . . . . . . . . . . . . . 21 3 pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 3.1 pad layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 4 application examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
preliminary data sheet 2 2001-05 foa2322a 3.2 gbit/s laser driver ic for telecom and datacom applications foa2322a 1 overview 1.1 features ? data rate up to 3.2 gbit/s supply range from +3.0 v to +5.5 v modulation current adjustable up to 75 ma bias current adjustable up to 80 ma choice between temperature compensation and integrated two-loop-control of bias and modulation current integrated laser supervisor monitor output for optical output power 1.2 applications fiber optics telecom and data communication systems sdh / sonet, fiber channel, gigabit ethernet 1.3 technology bicmos b6hfc 1.4 general this document defines the ratings and characteristics of a laser driver circuit dedicated for applications within telecom and datacom modules with respect to various transmission standards and laser safety requirements. a block diagram of this circuit is shown in figure 1 . modulation control / modulator / input stage the modulator is capable of driving modulation currents up to 75 ma. there are two modes for adjusting the modulation current: mode 1: the modulation current is adjusted by an external resistor ( r mod ). the ic has an internal temperature compensation circuit for compensating the temperature characteristic of laser diode slope efficiency. with the external resistor ( r tc ) the modulation current temperature coefficient is adjustable. the temperature input itself is derived from chip junction temperature.
foa2322a overview preliminary data sheet 3 2001-05 mode 2: the modulation current is controlled by using a low frequency pilot signal. the controller cutoff frequency is adjustable by external capacitor ( c mod ). mode 2 is suitable for data rates 1.25 gbit/s (depending on laser diode). there is an option for using data input latch. input signal monitor an input signal monitor circuit delivers a logic signal hwa and an internal signal which is used for laser disabling if data input is constantly high or low. bias control / bias generator the bias controller controls the ld optical output power by adjusting the bias current. the controller cutoff frequency is adjustable by external capacitor ( c bias ). a min. cutoff frequency is integrated. the laser bias current will start at < 500 a after laser enable. laser supervisor / v cc supervisor the laser supervisor circuit monitors the laser output power by the means of monitor diode feedback. the voltage generated by monitor diode circuit is compared to a reference. if the input voltage deviates more than 2 db (optical power 1 db) from this reference the laser diode is switched off and a fault indication is generated. the v cc supervisor monitors the circuit power supply and switches off the laser if the v cc level is below the reset threshold. it is keeping the laser output down for the adjusted delay time (power on delay) after v cc has risen above the v cc reset threshold.
foa2322a overview preliminary data sheet 4 2001-05 figure 1 general circuit block diagram ? number of pins: 42 ? ic available as die itb11326 bias control bias generator temperature compensation modul. control incl. oscillator start mode latch input stage modulator laser supervisor modulation enable bias enable v cc supervisor v ccd v ee v ee cbias rpout mpout v ee1 v bias i bias rmod rtc cosc mx cmod rmrip rbrip v ee2 v ee2 on on o o v mod hwa lf ldoff v cca v ccd2 cilm cism cfdel len rst rstn d dn clk clkn cseln md
foa2322a electrical characteristics preliminary data sheet 5 2001-05 2 electrical characteristics 2.1 absolute maximum ratings absolute maximum ratings which may not be exceeded to the device without causing permanent damage or degradation. exposure to these values for extended periods may effect device reliability. if the device is operated beyond the range of operating conditions and characteristics functionality is not guaranteed. all voltages given within this data sheet are referred to v ee if not otherwise mentioned. table 1 absolute maximum ratings parameter sym- bol limit values unit condi- tions min. max. supply voltage -0.3 6 v ? output voltage at o, on v cc - 2.6 v cc + 0.3 v 1) output voltage at mpout -0.3 v cc + 0.3 v 1)2) output voltage at logic output lf, hwa -0.3 v cc + 0.3 v 1) output voltage at ibias -0.3 v cc + 0.3 v 1)2) input voltage at logic inputs len, rst, rstn, cseln -0.3 v cc + 0.3 v 1) differential data input voltage | v d - v dn | ? 2.5 v ? differential data input voltage | v clk - v clkn | ? 2.5 v ? sink current at logic output lf, hwa ? 5 ma ? source current at ldoff -4 ? ma ? source current at rpout -2 ? ma ? modulation current at o, on (both outputs) ? 80 ma ? bias current at ibias ? 95 ma ? modulation control sink current at vmod (input current for current mirror 1:10) ? 9.6 ma ? bias control sink current at vbias (input current for current mirror 1:25) ? 4.8 ma ? modulation current adjust resistor r mod 800 ? ? ?
foa2322a electrical characteristics preliminary data sheet 6 2001-05 note: stresses above the ones listed here may cause permanent damage to the device. exposure to absolute maximum rating conditions for extended periods may affect device reliability. 2.2 general operating conditions under the below defined operating conditions all specified characteristics will be met unless otherwise noted. modulation temperature coefficient resistor r tc 50 ? ? ? junction temperature -40 125 c ? storage temperature -55 150 c ? relative humidity (non-condensing) ? 95 % ? electrostatic discharge voltage capability ? 1 kv ? 1) maximum voltage is 6 v. 2) for applications with v cc + 5 v (please refer to figure 13 ). table 2 general operating conditions parameter sym- bol limit values unit condi- tions min. max. environmental junction temperature -40 125 c 1) 1) for modulation current i oh 50 ma -40 110 2) 2) for modulation current 50 ma < i oh 75 ma relative humidity (non-condensing) ? 95 % ? supply voltage v cc range 3 5.5 v 3) 3) valid for v cca and v ccd ; v cca v ccd table 1 absolute maximum ratings (cont ? d) parameter sym- bol limit values unit condi- tions min. max.
foa2322a electrical characteristics preliminary data sheet 7 2001-05 2.3 characteristics and operating conditions table 3 characteristics and operating conditions sp parameter sym- bol limit values unit condi- tion min. typ. max. modulator / modulation control 1 data transmission rate dr 0 ? 2.5 gbit/s 1) 2 supply current i cc ? 30 63 ma 2)3) 3 modulation current high at o/on for v cc =3.3v for v cc =5v i oh - i ol 5 5 ? ? 65 75 ma 4)5) 4 modulation current low at o/on i ol 0 ? 2 ma 6) offset 5 modulation current at laser shut down i osd 0 ? 200 a 7) 6 o, on output voltage range for v cc =3.3v for v cc =5v v o , v on v cc - 1.65 v v cc - 2.0 v ? ? v cc v cc v 8) 7 modulation current adjust resistor range (mod-resistor) r mod 800 ? open input ? 9)10) 8 modulation temperature coefficient resistor range r tc 50 ? open input ? 9)11) serial data/clock input 9 data input voltage high v ihd ? ? v ccd v ? 10 data input voltage low for v ccd =3.3v for v ccd =5v v ild 1.0 2.2 ? ? ? ? v ? 11 data input voltage swing | v d - v dn | 250 ? 1600 mv ? 12 clock input voltage high v ihclk ? ? v ccd - 0.65 v ?
foa2322a electrical characteristics preliminary data sheet 8 2001-05 13 clock input voltage low for v ccd =3.3v for v ccd =5v v ilclk 1.0 2 ? ? ? ? v ? 14 clock input voltage swing | v clk - v clkn | 250 ? 1100 mv ? 15 bias voltage at d/dn v bbd ? v ccd - 1.0 ? v 12) 16 bias voltage at clk/clkn v bbc ? v ccd - 1.3 ? v 12) 17 differential data/clock input termination r in 80 100 120 ? 12)13) 19 input capacitance d/dn/clk/clkn c in ? ? 0.6 pf ? 20 setup time (data/clock) t setup ? 20 ? ps ? 21 hold time (data/clock) t hold ? 20 ? ps ? 22 eye opening at 2.5 gbit/s (w. latch) t eo ? 360 ? ps ? input signal monitor (ism) 23 internal ism cutoff frequency f ism 165 238 372 khz 14) 24 cutoff frequency of ism with external c ism f ism (6.1 s +84k ? c ism ) -1 (4.2 s +70k ? c ism ) -1 (2.7 s +56k ? c ism ) -1 14)15) 25 internal ilm cutoff frequency f ilm ? 160 ? khz 14) 26 cutoff frequency of ilm with external c ilm =1nf f ilm ? 73 ? khz 14)15) 27 duty cycle for laser enable 25 ? 75 % ? 28 duty cycle for laser disable 0 ? 5 % input low 29 duty cycle for laser disable 95 ? 100 % input high table 3 characteristics and operating conditions (cont ? d) sp parameter sym- bol limit values unit condi- tion min. typ. max.
foa2322a electrical characteristics preliminary data sheet 9 2001-05 laser power control 30 bias current i ibiasmax 0 ? 80 ma ? 31 start bias current i ibiasmin ? ? 500 a ? 32 bias current at laser shut down i ibiassd ? ? 500 a ? 33 output voltage range ibias v ibias 0.5 ? v cc v ? 34 power monitor current i mpout 0 v md r pout 1 ma 16) 35 output voltage range mpout v mpout v rpout + 0.5 ? v cc v ? 36 resistor range rpout r pout 2.4 ? open input k ? ? 37 output voltage range rpout v rpout 0 v md v cc - 1.2 v ? 38 internal cutoff frequency of bias controller f bias 23 37 62 khz 17) 39 cutoff frequency of bias controller with external c bias f bias (44 s+ 306 k ? c bias ) -1 (27 s+ 204 k ? c bias ) -1 (16 s+ 131 k ? c bias ) -1 15)17) 40 conversion gain of bias generator g bias ? 100 ? ma/v ? laser supervising circuit 41 md failure voltage high ? v mdnom + 1.5 db v mdnom + 2db 18) 42 md failure voltage low v mdnom - 2db v mdnom - 1.55 db ? 18) 43 md range without failure recognition v mdnom - 1.2 db ? v mdnom + 1.2 db v 19) 44 internal failure recognition time t fdel 38 60 86 s 17)20) 45 additional failure recognition time by external c fdel t fdel c fdel 0.7 s/pf c fdel 1.0 s/pf c fdel 1.3 s/pf 15)17)20) table 3 characteristics and operating conditions (cont ? d) sp parameter sym- bol limit values unit condi- tion min. typ. max.
foa2322a electrical characteristics preliminary data sheet 10 2001-05 46 shut off time after lf transition or laser disable t lddis 0 ? 3 s 21) 47 v cc reset threshold for laser enable/disable 2.5 2.75 2.99 v 22) 48 internal power on delay t pdel 213 333 480 s 23) 49 additional power on delay by external c osc t pdel 64 c osc 138 k ? 64 c osc 173 k ? 64 c osc 208 k ? 15)23) 50 ldoff low output current 1.5 ? 4 ma sink current 51 ldoff high output current ? ? 2 a sink current 52 ldoff high output voltage v cc -0.1 ? ? v ? 53 ldoff low output voltage v cc -2.0 ? v cc -1.2 v without external load reference voltage 54 md reference value v mdr 1.12 ? 1.32 v 24) 55 v mdr drift over temperature range | ? v mdr / v mdr | ? ? 5 % ? 56 v mdr drift over supply voltage range 3v ? 5.5 v | ? v mdr / v mdr | ? ? 10 % ? 57 v mdr drift over temperature range at supply voltage range 3v ? 3.6 v | ? v mdr / v mdr | ? ? 5 % ? 58 v mdr drift over temperature range at supply voltage range 4.7 v ? 5.3 v | ? v mdr / v mdr | ? ? 5 % ? table 3 characteristics and operating conditions (cont ? d) sp parameter sym- bol limit values unit condi- tion min. typ. max.
foa2322a electrical characteristics preliminary data sheet 11 2001-05 logic inputs rstn, rst, len 59 input voltage high v ihlogic 2.0 ? v cc v 25) 60 input voltage low v illogic 0 ? 0.8 v 25) 61 input current high i ihlogic ? ? 5 a ? 62 input current low i illogic -5 ? ? a ? logic inputs cseln 63 input voltage high for disabling data input latch (nonclocked mode) or let cseln open v ihlogic 2.2 ? v cc v ? 64 input voltage low for enabling data input latch (clocked mode) v illogic 0 ? 0.8 v ? 65 internal pull-up-resistor r cseln 8 10 12 k ? ? logic outputs lf, hwa 66 output voltage low v ollogic ? ? 0.4 v ? 67 output current high (leakage current) i ohlogic ? ? 100 a open collector 68 output current low i ollogic 2 ? ? ma sink current modulation control (mode 2) 69 mode 1 select v mode v cc -0.8 ? v cc v ? 70 mode 2 select v mode 0 ? 0.8 v ? 71 internal pilot frequency f pilot 7.7 12 17.3 khz ? 72 pilot frequency with external c osc f pilot (130 s+ 16 c osc 208 k ? ) -1 (83 s+ 16 c osc 173 k ? ) -1 (58 s+ 16 c osc 138 k ? ) -1 15) 73 effective pilot current amplitude on modulation current high level (default) am pilot ? 3.5 ? % 26) table 3 characteristics and operating conditions (cont ? d) sp parameter sym- bol limit values unit condi- tion min. typ. max.
foa2322a electrical characteristics preliminary data sheet 12 2001-05 74 pilot current amplitude on bias current (default) ab pilot ? 5.05 ? % 26) 75 cutoff frequency of modulation controller with external c mod f mod (306 k ? c mod ) -1 (204 k ? c mod ) -1 (131 k ? c mod ) -1 15)17) 1) measured into 25 ? . 2) the bias-, modulation-, the lf-, hwa- and mpout- output currents are not included. 3) the typical supply current is defined for driving a laser with about 20 ma bias current and about 20 ma modulation current and a ic junction temperature of about 50 c and a v cc of 5 v. the maximum supply current is defined for driving the upper limits of bias current and modulation current with worst case junction temperature and with a v cc of 5.5 v ( v cc = v cca = v ccd ). 4) this describes the ac modulation current (the dc component is the overall offset current). ac modulation current is drawn by o at v d > v dn , it is drawn by on at v d < v dn . i oh refers to drawn modulation current (ac + dc). i ol refers to an inactive current output (dc current only). 5) see table 2 for operating conditions junction temperature. 6) inactive current output (see also 4) ). 7) modulation current when the laser diode is disabled. 8) valid for v cc = v cca = v ccd = 5 v. it is possible to increase the output voltage range for the v cc range of 5v 0.5 v of about 0.85 v by using the pad v ccd2 instead of v ccd (see figure 14 ). the specified limits for data and clock inputs are valid for v ccd . 9) adjustment of programmable parameter by resistor value within this range (see chapter 2.4 ). 10) adjusting the modulation current by r mod notice that the decreasing of r mod will increase the modulation current. r mod in combination with r tc has to be adjusted that the modulation current is smaller than 50 ma or 75 ma respectively over specified temperature range. if r mod -pad is not connected (open input) there will be no modulation current at the output o/on. 11) modulation current adaptation within junction temperature range. low junction temperature represents a low additional modulation current. high junction temperature represents a high additional modulation current. if r tc -pad is not connected there will be no noteworthy modulation current adaptation. 12) data/clock inputs are internally connected to v bbd / v bbc by resistor r 1 / r 2 with a differential termination by r in . see data input stage description (see figure 9 ). 13) the resistance is guaranteed for junction temperature 25 c. table 3 characteristics and operating conditions (cont ? d) sp parameter sym- bol limit values unit condi- tion min. typ. max.
foa2322a electrical characteristics preliminary data sheet 13 2001-05 14) if data input duty cycle falls below lower limit or exceeds upper limit the laser will be disabled by ism circuit. on the other hand, the laser will be enabled whenever the data input duty cycle goes back to the allowed range. data input duty cycle refers to the quotient given by number of ones divided by number of zeros within serial data stream. the ism-circuit evaluates the mean value of the duty cycle (integrator). the cutoff frequency of ism f ism is defined for data pattern 1010 ?. in case of data frequency is to small the ism circuit will disable the laser because of long high- or low-series. the ism-circuit can be deactivated by a 25 k ? resistor from cism to v ee . the ilm-circuit additionally is used for ac-coupled data inputs. it works as a peak detector. the laser will be disabled if data are set to a static state. the cutoff frequency of ilm film is defined for data pattern 1010 ?. (specified value is for data input voltage swing of 400 mv).the ilm-circuit is direct ac-coupled to the data input. so the cutoff frequency depends on data input swing. the ilm-circuit can be deactivated by a short from cilm to v cc . 15) a capacitor within this range programs the time (or frequency). 16) open collector output for pulling up a resistor to monitor the current. 17) difference and temperature drift of passive ic component parameters match to passive ic component parameters in other circuit parts. 18) the supervisor circuit will detect a failure condition if md voltage exceeds v mdnom 2 db range. v mdnom is given by nominal voltage level at md which is set by v mdr . the deviation is calculated with 20lg( v md / v mdnom ). the deviation of optical power is calculated with 10lg( v md / v mdnom ). 19) the supervisor circuit will detect no failure condition if md input voltage ranges from v mdnom -1.2db to v mdnom + 1.2 db. v mdnom is given by nominal voltage level at md which is set by v mdr . the deviation is calculated with 20lg( v md / v mdnom ). the deviation of optical power is calculated with 10lg( v md / v mdnom ). 20) a failure condition will be reported by lf = h if this condition lasts for t fdel . minimal capacitor on cfdel has to be chosen that the failure recognition time is longer than the setting time of the bias controller. 21) time between lf high (or len high) and ldoff high. 22) at supply voltages below v cc threshold the laser diode bias and modulation current will be held disabled and ldoff will be held high. above the laser diode will be enabled after the power on delay. 23) the power on delay is the reset time after v cc voltage has risen above the v cc reset threshold. during the power on delay the laser diode bias and modulation current will be held disabled and ldoff will be held high. 24) temperature and voltage drift are included. 25) the minimal enable pulse width time for rst = l or rstn = h or len = l has to be longer then t fdel . 26) out of am pilot and ab pilot a factor k = ab pilot /am pilot can be defined, which is an important factor for the pilot control (for definition of am pilot and ab pilot see figure 8 ). for most laser diodes the optimum value of k is 1.44 (default value). if k is set close to factor 2 the modulation current and jitter may increase. if k is set close to factor 1 the modulation current may decrease. in both cases a malfunction of laser control is possible. a resistor between v cc and rmrip can be used for decreasing am pilot . further a resistor between v cc and rbrip can be used for decreasing ab pilot . so the factor k can be adjusted. for default factor k let rbrip and rmrip connected to v cc (= v cca ).
foa2322a electrical characteristics preliminary data sheet 14 2001-05 2.4 typical characteristics of temperature compensation (mode 1) 2.4.1 modulation current swing versus r mod , r tc , junction temperature and supply voltage / high current drive figure 2 f = i 100 c / i 0 c versus r tc , parameter r mod , v cc figure 3 i 0 versus t j , parameter r mod , r tc ( v cc =3.3v) itd11327 0 1.2 r tc 500 1000 1500 2000 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 k ? f 2 k ? /3.3 v 4 k ? /3.3 v 4 k ? /5 v 2 k ? /5 v itd11328 -50 10 t ?c i o 20 30 40 50 60 70 80 -30 -10 10 30 50 70 90 130 ma 2 k ? /700 ? 2 k ? /200 ? 2 k ? /2 k ? 4 k ? /200 ? 4 k ? /700 ? 4 k ? /2 k ? 110
foa2322a electrical characteristics preliminary data sheet 15 2001-05 figure 4 i 0 versus t j , parameter r mod , r tc ( v cc =5.0v) itd11329 -50 0 t ? c i o -30 -10 10 30 50 70 90 130 ma 10 20 30 40 50 60 70 80 100 2 k ? /700 ? 2 k ? /200 ? 2 k ? /2 k ? 4 k ? /200 ? 4 k ? /700 ? 4 k ? /2 k ? 110
foa2322a electrical characteristics preliminary data sheet 16 2001-05 2.4.2 modulation current swing versus r mod , r tc , junction temperature and supply voltage / low current drive figure 5 f = i 100 c / i 0 c versus r tc , parameter r mod , v cc figure 6 i 0 versus t j , parameter r mod , r tc ( v cc =3.3v) itd11330 1800 1.00 f 1.05 1.10 1.15 1.20 1.25 1.30 1.40 2800 3800 4800 5800 6800 7800 9800 r tc k ? 5 k ? /3.3 v 5 k ? /5 v 10 k ? /5 v 10 k ? /3.3 v itd11331 -50 5 t ? c i o -30 -10 10 30 50 70 90 130 ma 6 7 8 9 10 11 12 13 14 15 16 18 10 k ? /2 k ? 10 k ? /5 k ? 10 k ? /9.5 k ? 5 k ? /5 k ? 5 k ? /2 k ? 5 k ? /9.5 k ? 110
foa2322a electrical characteristics preliminary data sheet 17 2001-05 figure 7 i 0 versus t j , parameter r mod , r tc ( v cc =5.0v) itd11332 -50 5 t j i o 6 7 8 9 10 11 12 13 14 15 16 ma 18 -30 -10 10 30 50 70 90 110 130 ? c 10 k ? /2 k ? 10 k ? /5 k ? 10 k ? /9.5 k ? 5 k ? /2 k ? 5 k ? /5 k ? 5 k ? /9.5 k ?
foa2322a electrical characteristics preliminary data sheet 18 2001-05 2.5 principle of modulation current control by using a pilot signal (mode 2) the dc-part of the monitor current controls the bias current. the difference of the optical low frequency ac-part ? ppp is used for the modulation current control. ? ppp is measured over the monitor current. the aim of the control is to settle ? ppp to zero. (that means a part of the pilot current amplitude on bias current is modulated below laser current threshold. therefore please take into account the laser characteristics, e.g. switch-on delay, for higher data rates.) mode 2 can only be used for dc-coupled laser diodes. figure 8 modulation current control by using a pilot signal p opt p1 p p0 i laser ab pilot am pilot ? p1 ? ppp ? p0 ? ppp = ? p0 - ? p1 itd11333
foa2322a electrical characteristics preliminary data sheet 19 2001-05 2.6 data / clock input stage data and clock inputs are terminated with 100 ? and are connected to a v bb reference by resistors r 1 / r 2 . ( v bb for clock input is v bbc , v bb for data input is v bbd .) this easily provides the input reference voltage at ac coupling. a schematic of the input stage is shown below: figure 9 data/clock input stage 2.7 timing of clock and data figure 10 timing of clock and data its11334 p n r in r 1 r 2 reference generator v bb r 1 , r 2 = 5 k ? r in = 100 ? 20% itt11335 t setup t hold 50% 50% daten d/dn clock clk
foa2322a electrical characteristics preliminary data sheet 20 2001-05 2.8 laser and v cc supervising circuit if there is a laser fault (optical power deviates 1 db) this signal is stored and indicated by lf (logic high). the fault indication (lf) can be reset with low level at rstn or with high level at rst or with power down ( v cc < v cc reset threshold) only. after power up, lf will always be cleared. disabling the laser by len does not influence a previous fault indication by lf. the laser fault generation can be switched off by connecting cfdel to v cc . during rstn is logic low or rst is logic high the circuit is in reset state. in case of changing rst = h or rstn = l after laser fault recognition lf = h (after t fdel ) there is an additional delay time implemented which has the same value as the power on delay. if the supply voltage is lower than the v cc reset threshold the indicator hardware alarm (hwa) is still at the low level and the circuit is in reset state. during power on delay the circuit is in reset state too. the power on delay is defined as the delay after v cc voltage has risen above the v cc reset threshold. this time can be adjusted by an external capacitor at cosc (mode 1). the reset n-output of the max 809s power supervisor ic can be connected to rstn to use the reset function of the max 809s. the laser control by rst and rstn is fully redundant. this means only an and combination of rst = 0 / rstn = 1 can switch the laser on. the or combination of rst = 1 / rstn = 0 switches the laser off (see table 4 for clarification). table 4 shows the static states of these signals. dynamic changes or delays due to external delay capacitors are not shown. table 4 laser diode currents enable / disable signals rst len rstn in case of laser fault v cc < reset threshold v cc ldoff modulation enable 1) 1) internal signal bias enable 1) lf (high active) x 1 x 0 x 1 0 0 0 1 x x x x 1 0 0 0 x x 0 x x 1 0 0 0 x x x x yes 1 0 0 0 0 0 1 1 no 2) 2) after power on delay 1 3) 3) after t fdel 0 0 1 3) 0 0 1 0 no 2) 0 4) 4) sink current enabled = low 1 1 0
foa2322a electrical characteristics preliminary data sheet 21 2001-05 bias current is disabled by setting bias enable low, modulation current is disabled by setting modulation enable low. len do not effect lf. this means lf can not be reset by len. 2.9 input signal monitoring and hardware alarm (consideration in absence of laser fault) table 5 function of ism circuit and hardware alarm indicator (hwa) data level (after delay of ism) v cc < reset threshold of v cc /circuit in reset state ism laser enable 1) 1) internal signal ldoff hwa (low active) modulation enable 1) bias enable 1) constant high no 0 1 0 0 0 constant low no 0 1 0 0 0 constant high yes 0 1 0 0 0 constant low yes 0 1 0 0 0 duty cycle ok yes 1 1 0 0 0 duty cycle ok no 1 0 2) 2) sink current enabled = low 1 1 1
foa2322a pin description preliminary data sheet 22 2001-05 3 pin description table 6 pin definitions and functions signal name function explanation d / dn differential input differential data input. d corresponds to o and dn to on current output. with a high level at d and a low level at dn modulation current is drawn by o and on is inactive. with a low level at d and a high level at dn modulation current is drawn by on and o is inactive. both inputs are prebiased to internal v bbd . the input termination is 100 ? . clk / clkn differential input differential clock input for input data latch. the input termination is 100 ? . cseln logic input a low level at cseln enables the data input latch (clocked mode), a high level or an open input disables the data input latch (nonclocked mode). it has an internal pull-up-resistor of about 10 k ? . o / on differential current output these output signals drive the modulation current switched by d / dn data inputs. cmod control the modulation controller characteristic can be set to an i-controller with an external capacitor at cmod to v ee and the time constants are adjustable in mode 2. let open if mode 1 is used. vmod output base of the output current mirror 1:10. for normal application it can be leave open if not used. cism control with an external capacitor at cism to v cc the delay time for detection of a bad duty cycle data input situation can be increased. if the input signal monitor is not used cism has to be pulled down by 25 k ? resistor to v ee . cilm control with an external capacitor at cilm to v cc the delay time for detection of static data input situation can be increased. if the peak detector is not used cilm has to short to v cc . hwa logic output hwa is an open collector output (indicator output). a low level is generated whenever a bad duty cycle data input situation is detected by the input signal monitor circuit or if the supply voltage is lower than the v cc reset. let open if not used.
foa2322a pin description preliminary data sheet 23 2001-05 ibias bias output a sink current drawn by ibias determines the laser diode bias current. cbias control the bias controller characteristic is set to an i-controller. the cutoff frequency can be decreased by an external capacitor at cbias to v ee . mpout monitor output mpout is an open collector output for pulling up a resistor to monitor the deviation of the optical power over the monitor diode current. let open if not used. rpout control a resistor between rpout and v ee can adjust the relation of optical power measured over the monitor diode current to output current at mpout. let open if the monitoring of the optical power is not used. vbias bias output this output can be connected to the base of an external bias current npn transistor. it can be leave open if not used. it is dedicated for applications which can not use the internal bias transistor. base of the output current mirror 1:25. md monitor diode input this is the controller feedback input. the voltage at this input represents the monitor diode current and by this the laser output power. the bias current will be controlled to an equal level of v md and v mdr . ldoff laser shut down output whenever the laser diode is disabled ldoff will deliver a high voltage level closed to v cc . if the laser diode is enabled there is a sink current to drive the base of an external pnp transistor to support a laser diode supply shut down. if not used this output can be leave open without laser driver performance restrictions. there is an internal pull up resistor between ldoff and v cc a of 10k. rstn logic input low active reset input. this input resets the lf indication if present. further the laser diode is held within shut down mode if this signal is at low level. for constant laser diode enable this signal can be tied to v cc . table 6 pin definitions and functions (cont d) signal name function explanation
foa2322a pin description preliminary data sheet 24 2001-05 rst logic input high active reset input. this input resets the lf indication if present. further the laser diode is held within shut down mode if this signal is at low level. for constant laser diode enable this signal can be tied to v ee . len logic input a low level at len enables the laser diode, a high level disables the laser diode. for constant enable this input can be tied to v ee . lf logic output fault indicator. a high level is generated whenever a fault situation is detected by the supervisor circuit. fault situations are laser power failures indicated by md input voltage deviation from v mdnom . let open if not used. cfdel control with an external capacitor at cfdel to v ee the laser fault detection delay time can be increased. this means if a constant fault condition is present a laser fault indication will be generated and the laser will be shut down after this delay time. the laser safety circuit can be switched off if cfdel is connected to v cc . cosc control with an external capacitor at cosc to v ee the piloton frequency can be decreased (mode 2). cosc determines the power on delay. mode logic input a high level at mode sets the modulation control circuit to mode 1 (using temperature compensation circuit). a low level at mode sets the modulation control circuit to mode 2 (using modulation control by pilot signal). rmod control an external resistor at rmod to v ee sets the modulation current level (in mode 1). let open if mode 2 is used. rtc control an external resistor at rtc to v ee sets the modulation current temperature coefficient. the temperature information is derived from chip junction temperature (in mode 1). let open if mode 2 is used. table 6 pin definitions and functions (cont d) signal name function explanation
foa2322a pin description preliminary data sheet 25 2001-05 rbrip control the pilot current amplitude on bias current (mode 2) can be decreased by connecting a resistor between rbrip and v cc . for default values do connect to v cc . it has no influence if using mode 1. let open if mode 1 is used. rmrip control the pilot current amplitude on modulation current high level (mode 2) can be decreased by connecting a resistor between rmrip and v cc . for default values do connect to v cc . it has no influence if using mode 1. let open if mode 1 is used. start do not connect. mx do not connect. v cca power supply positive power supply for analog circuit part. v ccd power supply positive power supply for digital circuit part. v ccd2 power supply positive power supply for digital circuit part with an additional serial diode to increase the modulation output voltage range of about 0.85 v for v cc range of 5 v 0.5 v. let open if it is not used. v ee1 power supply negative power supply, only connected to the output current mirror stage of bias generator, normally gnd. v ee2 power supply negative power supply, only connected to the output stage, normally gnd. v ee power supply negative power supply of the rest of circuit, normally gnd. table 6 pin definitions and functions (cont d) signal name function explanation
foa2322a pin description preliminary data sheet 26 2001-05 3.1 pad layout figure 11 the pad center x/y positions are given in table 7 (related to the chip origin 0/0 excl. seal ring): itp11336 1 42 33 v cca s1048 rtc 2 32 3 31 30 4 29 5 6 28 7 27 26 8 25 9 10 24 11 23 22 v ee1 12 rmod 41 40 cmod rmrip 39 38 37 36 35 34 13 14 15 16 17 18 19 20 21 rpout v ee v ee cism cseln clkn clk len dn d rst cilm rstn cfdel mpout cbias md cosc mode mx v bias i bias v ee2 on v ee2 v c c d 2 v m o d v c c d on o o start rbrip lf hwa ldoff y x
foa2322a pin description preliminary data sheet 27 2001-05 die size: 1.92 mm 1.64 mm (excl. seal ring) chip thickness: 300 m frame grid: 2.024 mm 1.75 mm bondpad window: 80 m 80 m bondpad material: aluminium substrate: v ee table 7 pad positions bottom: 1-12 right: 13-21 top: 33-22 left: 42-34 x / m y / m x / m y / m x / m y / m x / m y / m 271 137 1777 267 271 1498 141 267 396 137 1777 391 396 1498 141 391 521 137 1777 516 521 1498 141 516 646 137 1777 693 646 1498 141 693 771 137 1777 818 771 1498 141 818 896 137 1777 943 896 1498 141 943 1021 137 1777 1119 1021 1498 141 1119 1146 137 1777 1244 1146 1498 141 1244 1271 137 1777 1369 1271 1498 141 1369 1396 137 1396 1498 1521 137 1521 1498 1646 137 1646 1498
foa2322a application examples preliminary data sheet 28 2001-05 4 application examples figure 12 application example a: using mode 1 its11337 bias control bias generator temperature compensation modul. control incl. oscillator start mode latch input stage modulator laser supervisor modulation enable bias enable v cc supervisor v ccd v ee v ee cbias rpout mpout v ee1 v bias i bias rmod rtc cosc mx cmod rmrip rbrip v ee2 v ee2 on on o o v mod hwa lf ldoff v cca v ccd2 cilm cism cfdel len rst rstn d dn clk clkn cseln optional optional optional v cc v cc v cc v cc md
foa2322a application examples preliminary data sheet 29 2001-05 figure 13 application example b: power supply with +5 v ? 0 v (gnd) ? -5 v using mode 2 its11338 bias control bias generator temperature compensation modul. control incl. oscillator start mode latch input stage modulator laser supervisor modulation enable bias enable v cc supervisor v ccd v ee v ee cbias rpout mpout v ee1 v bias i bias rmod rtc cosc mx cmod rmrip rbrip v ee2 v ee2 on on o o v mod hwa lf ldoff v cca v ccd2 cilm cism cfdel len rst rstn d dn clk clkn cseln optional optional -5 v -5 v x1 -5 v -5 v -5 v -5 v -5 v x2 -5 v -5 v -5 v -5 v x1 x2 current outputs pulled up to +5 v (e.g. 2 bcx68)
foa2322a application examples preliminary data sheet 30 2001-05 figure 14 application example c: using v ccd2 for increasing the modulation output voltage range for the v cc range of 5 v 0.5 v (here mode 1) its11344 bias control bias generator temperature compensation modul. control incl. oscillator start mode latch input stage modulator laser supervisor modulation enable bias enable v cc supervisor v ccd v ee v ee cbias rpout mpout v ee1 v bias i bias rmod rtc cosc mx cmod rmrip rbrip v ee2 v ee2 on on o o v mod hwa lf ldoff v cca v ccd2 cilm cism cfdel len rst rstn d dn clk clkn cseln optional optional optional v cc v cc v cc v cc md
foa2322a application examples preliminary data sheet 31 2001-05 figure 15 application example d: several kinds for connecting laser diode (1300 nm-fp-laser, 5 ? ); resistor values are proposed values. they depend on used laser diodes, currents and mechanical and pcb design. its11339 50 ? 50 ? 100 nf 220 nh 20 ? r comp [xx ? ] c comp [x pf] 100 nf 20 ? 220 nh v cc on o i bias its11340 50 ? r comp [xx ? ] c comp [x pf] 100 nf 20 ? 220 nh v cc on o i bias 16.7 ? its11341 220 nh r comp [xx ? ] c comp [x pf] 10 ? 220 nh v cc on o i bias 10 ? its11342 r comp [xx ? ] c comp [x pf] 10 ? 220 nh v cc on o i bias 15 ?
foa2322a application examples preliminary data sheet 32 2001-05 figure 16 application example d: several kinds for connecting laser diode (1300 nm-fp-laser, 5 ? ) (cont d) ; its11343 100 ? r comp [xx ? ] c comp [x pf] 100 nf 20 ? 220 nh v cc on o i bias l large l = 5.6 nh l large l = 5.6 nh 100 ?
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