rev. 0 a adn2845 10.709 gbps high speed data switch information furnished by analog devices is believed to be accurate and reliable. however, no responsibility is assumed by analog devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. no license is granted by implication or otherwise under any patent or patent rights of analog devices. trademarks and registered trademarks are the property of their respective companies. one technology way, p.o. box 9106, norwood, ma 02062-9106, u.s.a. tel: 781/329-4700 www.analog.com fax: 781/326-8703 ? 2003 analog devices, inc. all rights reserved. features data rates from 9.952 gbps to 10.709 gbps typical rise/fall time 25 ps/23 ps bias current range 3 ma to 80 ma modulation current range 5 ma to 80 ma automatic laser shutdown, als cml data inputs 50 internal data terminations 3.3 v single-supply operation driver supplied in die format only applications sonet oc-192, sdh stm-64 supports 10.667 gbps and 10.709 gbps fec rates 10 gb ethernet ieee802.3ae functional block diagram datap datan als imod_ctrl ibias_ctrl 50 50 ibias imodp v cc ld adn2845 general description the adn2845 is a 10.709 gbps laser diode driver. the adn2845 eliminates the need to ac-couple since it can deliver 80 ma of modulation while dc-coupled to the laser diode. it is intended to be copackaged with the laser to minimize bond lengths, which improves performance of the optical transmitter. the adn2845 may be used in conjunction with the adn2844 control chip. this chipset (adn2843) offers a unique control algorithm to control both average power and extinction ratio of the laser diode. for transmission line applications, contact the hsn applications group at fiberoptic.ic@analog.com
rev. 0 ? adn2845-specifications electrical characteristics parameter min typ max unit conditions laser bias (bias) output current i bias 380ma compliance voltage 1.2 v cc ?.0 v i bias during als 10 as ee note 1 als shutdown response time 10 s modulation current (lmodp, imodn) see note 2 output current i mod 580ma compliance voltage 1.2 v cc v i mod during als 10 a rise time 25 ps fall time 23 ps random jitter 170 fs rms see note 3 total jitter 7.41 ps p-p see note 4 data inputs (datap, datan) v p-p(single-ended peak-to-peak) 300 800 mv input impedance 50 logic inputs (als) v ih 2.4 v v il 0.8 v imod_ctrl input see note 5 gain (imod_ctrl to i mod )1 0 15.5 a/a input voltage 1.5 v ibias_ctrl input see note 5 gain (ibias_ctrl to i bias )912 a/a input voltage 1.5 v supply v cc 3.0 3.3 3.6 v i cc 75 ma see note 6 notes 1 in als mode, approximately 15 ma is sourced to the laser from the ibias pin, which reverse biases the laser. 2 the adn2845 high speed specifications are measured into a 5 load. 3 rms jitter measured with a 0000 0000 1111 1111 repeating pattern at 10.7 gbps rate. 4 peak-to-peak total jitter measured with a 2 13 ?1 prbs pattern with 80 cids input pattern at 10.7 gbps rate. 5 it is recommended to decouple these pins to v cc rather than gnd. 6 ibias = 0, imod = 0 (when als is asserted). see power dissipation section on page 4 for calculation of complete power dissipati on. specifications subject to change without notice. (v cc = 3.0 v to 3.6 v. all specifications t min to t max , unless otherwise noted. typical values as specified at 25 c.) absolute maximum ratings * (t a = 25?, unless otherwise noted.) v cc to gnd . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 v datap to gnd . . . . . . . . . . . . . . . . . . . . . . . ?.5 v to 4.2 v datan to gnd . . . . . . . . . . . . . . . . . . . . . . ?.5 v to 4.2 v als to gnd . . . . . . . . . . . . . . . . . . . . . . . . . . ?.5 v to 4.2 v imod_control to gnd . . . . . . . . . . . . . ?.5 v to 4.2 v ibias_control to gnd . . . . . . . . . . . . . . ?.5 v to 4.2 v imodn, imodp . . . . . . . . . . . . . . . . . . . . . . . . . v cc +1.2 v operating temperature range industrial . . . . . . . . . . . . . . . . . . . . . . . . . . . ?0? to +85? storage temperature range . . . . . . . . . . . . . ?5? to +150? junction temperature (t j max) . . . . . . . . . . . . . . . . . . . 150? * stresses above those listed under absolute maximum ratings may cause perma- nent damage to the device. this is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. ordering guide temperature package qty. model range description min. adn2845achips ?0? to +85? die form 100
rev. 0 adn2845 ? pin configuration d ata n gnd nc datap gnd v cc (i modn term) nc imodp nc ibias v cc gnd als imod_ctrl ibias_ctrl gnd 1 adn2845 p ad pitch: 200 m die size: 1140 m ( 20 m) 1340 m ( 20 m) die thickness: 0.25mm single pad size: 92 m 92 m double pad size: 151 m 92 m v cc v cc caution esd (electrostatic discharge) sensitive device. electrostatic charges as high as 4000 v readily accumulate on the human body and test equipment and can discharge without detection. although the adn2845 features proprietary esd protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. therefore, proper esd precautions are recommended to avoid performance degradation or loss of functionality. pin function descriptions pin no. mnemonic function 1 datan ac-coupled cml data, negative differential terminal 2g nd negative supply 3n cn o connect. leave floating. 4g nd negative supply 5 datap ac-coupled cml data, positive differential terminal 6 als automatic laser shutdown logic input 7i mod_ctrl modulation current control input (control circuit sinks imod/10 from pin to gnd.) 8i bias_ctrl bias current control input (control circuit sinks ibias/10 from pin to gnd.) 9g nd negative supply 10 nc no connect. leave floating. 11 ibias bias current 12 imodp modulation current 13 nc no connect. leave floating. 14 v cc v cc connection for imodn termination resistor 15 gnd negative supply 16 v cc positive supply 17 v cc positive supply 18 v cc positive supply metallization photograph gnd v cc v cc v cc nc nc imodp ibias gnd ibias_ctrl als imod_ctrl gnd datap gnd datan 1340 m ( 20 m) 1140 m ( 20 m) nc v cc (im odn term) die pad coordinates 1 pad no. pad name x ( m) y ( m) 1 datan ?00.00 400.00 2 gnd 2 ?00.00 222.00 3n c ?00.00 0.00 4 gnd 2 ?00.00 ?22.00 5 datap ?00.00 ?00.00 6 als ?00.00 ?00.00 7i mod_ctrl ?00.00 ?00.00 8i bias_ctrl 100.00 ?00.00 9 gnd 2 300.00 ?00.00 10 nc 2 500.00 ?00.00 11 ibias 500.00 ?00.00 12 imodp 2 500.00 ?0.00 13 nc 2 500.00 178.00 14 v cc (imodn term) 2 500.00 378.00 15 gnd 2 300.00 600.00 16 v cc 2 100.00 600.00 17 v cc 2 ?00.00 600.00 18 v cc 2 ?00.00 600.00 notes 1 the reference point with x = 0, y = 0 is the center of the die. 2 denotes double bond pad.
rev. 0 ? adn2845 general the adn2845 is a 3.3 v high speed data switch that is intended to be dc-coupled with a copackaged laser diode. achieving best performance requires using low inductance ribbon connections between the adn2845 and the laser. imod__crtl, ibias_ctrl the operation of the adn2845 is controlled by the two input pins called ibias_ctrl and imod_ctrl. the user should connect current sinks from each of these pins to gnd. these currents are internally mirrored and used to control the actual values for the bias and modulation currents used to drive the laser diode. it is recommended to decouple these pins to v cc instead of gnd. data inputs figure 1 shows a simplified schematic of the adn2845 data inputs. the data inputs are terminated via the equivalent of a 100 internal resistor between datan and datap. this provides 50 termination for single-ended signals. the actual signal on the switching devices is attenuated by a factor of 2 25 figure 1. simplified schematic of the data inputs internally. there is a high impedance circuit to set the common- mode voltage, which is designed to change over temperature. it is recommended that ac coupling be used to eliminate the need for matching between the common-mode voltages. laser shutdown the adn2845 als allows compliance to itu-t-g958 (11/94), section 9.7. when als is asserted, both bias and modulation currents are turned off. in asl mode, approximately 15 ma is sourced to the laser from the ibias pin, which reverse biases the laser and ensures that it is turned off. als should have a 10 k w pull-down resistor connected and should be driven with correct logic levels (see specifications section). the als pin should never be left floating. power dissipation the power dissipation of the adn2845 can be calculated using the following expressions: imaima ima cc mod bias =+ + 75 1 75 0 3 .().() pv i a v ia via cc cc imod mod ibias bias = + + () () () 2 where v imod is the average voltage on the imod pin, and v ibias is the average voltage on the ibias pin. d ata n gnd d ata p gnd ld imodp ibias v cc gnd als imod_ctrl ibias_ctrl gnd adn2845 1 5 9 15 18 10nf 10nf 10nf 10 f t antalum 10nf v cc 10nf 10nf 10nf v cc v cc v cc v cc v cc v cc v cc v cc 6 14 10 10k imodnterm figure 2. adn2845 application circuit
rev. 0 adn2845 ? ground plane parallel plate decoupling capacitor notes ? for optimum performance, ribbon bonds are recommended on pads 1, 5, 12, and 14. wires are 3 mil or 5 mil ribbons <400 figure 3. recommended layout figure 4. 10 gbps optical diagram provided courtesy of nel. p av = 0 dbm, er = 5 db, prbs 31 pattern.
rev. 0 ? adn2845 outline dimensions 18-pad bare die dimensions shown in micrometers and millimeters 1 adn2845 p ad pitch: 200
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