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c reate ? 2005 icreate technologies corporation apd-8011-001 i7110 300 mbps led drivers data sheet icreate technologies corporation
i7110 ? 2005 icreate technologies corporation apd-8011-001 ? copyright 2005 icreate technologies corporation information contained in this publication is int ended through suggestion only and may be superseded by updates. no liability is assumed by icreate technologies corporation with respect to the use of such information or otherwise and no representation or warrant y is given. use of icreate?s products as critical components in life support systems is not authorized. no part of this document may be reproduced or trans mitted in any form or by any means for any purpose without the permission of icr eate. no licenses are conveyed, implicit ly or otherwise, under any intellectual property rights. the icreate logo and name are register ed trademarks of icreate te chnologies corporation. all rights reserved. all other trademarks mentioned herein are the property of their respective companies. data sheet marking icreate uses various markings in the data sheet to desig nate each document phase as it relates to the product development stage. marking description objective specification the objective specificat ion contains data for new product development. advance information the information is on products in the design phase. your designs should not be finalized with this information. preliminary this is preliminary information on new products but not yet fully characterized. the specifications in these data sheets are subject to change in any manner without notice. no marking information contained in the dat a sheet is on products in full production. for more information please contact: icreate technologies corporation no. 6, technology rd. v, science-based industrial park, hsinchu, taiwan 300 phone +886-3-579-0000 fax +886-3-579-0077 e-mail support@icreate.com.tw revision 3.00 date 05/2005
i7110 ? 2005 icreate technologies corporation page 1 apd-8011-001 +3.3v to +5.0v, 300mbps led driver 1 introduction 1.1 general description the i7110 is a high-speed led driver designed for low-cost optical fiber based transmission systems. data rates up to 300mbps can be achieved depending on the led used. the differential pecl inputs can be shaped by applying resistors between pulse width adjustment pins and ground. this adjustment is continuous over a 500ps range to compensate the led unbalanced ?turn on? and ?t urn off? time. a peaking and clamp circuit is implemented in i7110 to enhance speed performance and connecting external rc network performs this function. the i7110 can switch a wide range of current 5ma to 120ma into typical leds. to minimize the effects of temperature on led output power, the device's modulation current can be set via two external resistors to increase with a temperature coefficient from 800ppm/ to 10000ppm/ . complementary current outputs help to maintain a constant supply current, reducing emi and supply noise generated by the transmitter m odule, and the current is disabled if pin disa is pulled high. the i7110 is packaged in qsop16 and tssop20. 1.2 applications ? fddi ? sdh stm-1 ? sonet oc-3 ? fast ethernet ? fiber channel 1.3 features ? data rates up to 300 mbps, depending on led. ? +5 v to +3.3 v operation. ? programmable output current from 5ma to 120ma. ? peaking circuit giving rise and fall time < 700ps. ? clamping circuit enhances turn off time. ? resistor programmable compensation for temperature dependence of led output. ? pecl input with optional pulse width adjustment. ? support most led types. ? support output current disable ability. ? single chip solution, available in tssop20 or qsop16. 1.4 ordering information part no. package i7110-es 16-pin qsop I7110-EG 16-pin qsop i7110-ep 20-pin tssop * I7110-EG is provided in green package
i7110 page 2 ? 2005 icreate technologies corporation apd-8011-001 2 pin configuration and definition 2.1 pin configuration gnda disa ioutb iout iout peak vddc vddd vdda rset1 rset2 vref pwap qsop16 pwan i7110-es pwan gnda disa ioutb iout iout peak vddc vddd vdda rset1 rset2 vref dinn pwap dinp tssop20 nc nc nc i7110-ep nc dinn dinp figure 1. i7110 pin configuration
i7110 ? 2005 icreate technologies corporation page 3 apd-8011-001 2.2 pin definition pin name tssop20 pin no. qsop16 pin no. description nc 1 - not connected pwan 2 1 inverse pulse width adjustment input pwap 3 2 differential pulse width adjustment input. allows continuous adjustment of input data pulse width dinp 4 3 non inverting data input pin dinn 5 4 inverting data input pin vref 6 5 input reference voltage. connect vref to dinn for single ended input rset2 7 6 temperature compensation adjustment pin. allows temperature dependence of led light output to be reduced or removed rset1 8 7 set nominal led drive current vdda 9 8 power pin, connect to most positive supply nc 10 - not connected nc 11 - not connected vddd 12 9 power pin, connect to most positive supply vddc 13 10 led shorting pin, connect to most positive supply. speeds led switch off peak 14 11 connection for pre-emphasis or peaking circuit iout 15,16 12,13 driver output ioutb 17 14 connect a resistor between this pin and vcc disa 18 15 control pin for disable current-out gnda 19 16 ground pin
i7110 page 4 ? 2005 icreate technologies corporation apd-8011-001 3 block diagram bandgap & bias circuit current modulation pwap io u t peak rset2 rset1 vddc vddd vdda vref dinn dinp gnda io utb input buffer pulse width adjust driver peaking & clamping pwan disa figure 2. i7110 block diagram 4 electrical specifications 4.1 recommended operating conditions parameter symbol rating unit power supply vcc 3.0 to 5.5 v operating ambient ta -40 to 85
i7110 ? 2005 icreate technologies corporation page 5 apd-8011-001 4.2 dc electrical characteristics ( vcc = 3.0 v to 5.5 v, ta = -40 to 85 , unless otherwise noted. temperature coefficients are referenced to ta = +25 . typical values are at ta = +25 , vcc = 3.3v ) symbol parameter min typ max units v in_h input high voltage level vcc-1.0 - vcc-0.8 v v in_l input low voltage leve l vcc-2.0 - vcc-1.8 v iout_on led drive current 5 - 120 ma iout_off led off current - - 50 ua vref voltage reference vcc- 1.6 vcc-1.4 vcc-1.03 v vledh led headroom voltage - - 2 v 4.3 ac electrical characteristics ( vcc = 3.0 v to 5.5 v, ta = -40 to 85 , unless otherwise noted. temperature coefficients are referenced to ta = +25 . typical values are at ta = +25 , vcc = 3.3v ) symbol parameter min typ max units led t r led drive rise time - 0.7 1 ns led t f led drive fall time - 0.7 1 ns peak t r peaking current rise time - - 1 ns peak t f peaking current fall time - - 1 ns i dd supply current - i led +10 i led +20 ma
i7110 page 6 ? 2005 icreate technologies corporation apd-8011-001 4.4 typical operating curve (i7110 characteristic curve tested at vc c=3.3v , 5v. iout, ioutb connect 10 ? resistor to vcc, vref is floating , dinp connects to vcc, dinn connects to gnd) modulation current vs rset1vcc=3.3v modulation current vs rset2 vcc=3.3v figure 3 figure 5 modulation current vs rset1 vcc=5v modulation current vs rset2 vcc=5v figure 4 figure 6
i7110 ? 2005 icreate technologies corporation page 7 apd-8011-001 4.5 temperature compen sation contour plot (i7110 characteristic curve , relationship between m odulation current with rset1 & rset2. iout, ioutb connect 10 ? resistor to vcc, vref is floating , dinp connects to vcc, dinn connects to gnd ) 1000 10000 100000 100 1000 10000 100000 rrset2(ohm) rrset1(ohm) figure7. tj = 50 degree 1000 10000 100000 100 1000 10000 100000 rrset2(ohm) rrset2(ohm) figure8. tj = 75egree 1000 10000 100000 100 1000 10000 100000 rrset2(ohm) rrset1(ohm) figure 9. tj = 100degree 1000 10000 100000 100 1000 10000 100000 rrset2(ohm) rrset1(ohm) figure 10 tj = 125 degree 120ma 100ma 80ma 60ma 40ma 10ma 120ma 100ma 80ma 60ma 40ma 10ma 120ma 100ma 80ma 60ma 40ma 10ma 120ma 100ma 80ma 60ma 40ma 10ma
i7110 page 8 ? 2005 icreate technologies corporation apd-8011-001 4.6 detail description bandgap current modulation pwap io u t peak rset2 rset1 vddc vddd vdda vref dinn dinp gnd gnd io u tb input buffer pulse width adjust driver peaking & clamping pwan disa figure-11 the i7110 provides a flexible current drive for the modulation of the light-emitting diodes(leds). the circuit is designed to use 3.3v ~ 5v power supply. the ic provides up to 120ma of modulation current. figure-11 shows a typical block diagram of i7110, which comprises a bandgap, current modulation block, peaking and clamping block, an input buffer, pulse width adjustment function block and the output driver. reference-voltage generate the reference-voltage generator circuit provides single-ended input reference voltage vref. the vref is used to simplify the pecl- compatible input. for single-ended operation, connect the input signal to dinp, and connect dinn directly to vref. the vref circuit is not designed to drive other external circuitry. led drive and tempera ture compensation the two resistors rrset1 and rrset2 set the led drive current and temperature compensation. the simplified application diagram (figure-11) shows rrset1 connects between rset1 and gnd, and rrset2 connects between rset1 and rset2. rrset1 rrset2 rpeak cpeak
i7110 ? 2005 icreate technologies corporation page 9 apd-8011-001 figure-12 the current flows out of the rset1 pin determine the led drive current. the temperature independent led driving current is set mainly by rrset1, while the temperature dependent current is set mainly by rrset2. however rrset1 and rrset2 are not independent. the rset2 pin connects to an internal diode in the ic, which exhibits standard diode behavior with temperature. as temperature rises, the voltage on rset2 drops, the current flows through diode increases and the led drive current increases. given the various interdependencies of the drive current, rrset1 and rrset2, the relationship with temperature compensation is plotted in figure-12 peaking function to improve led ? turn on ? time an optional function ? peaking ? is included in ? i7110 ? . if this is not required, then the pin peak should be left floating. two external co mponents are required to implement peaking. as shown in figure-11. when the led is turned on, the voltage on peak is pulled low very rapidly. this voltage transient is coupled through rpaek and cpeak and exerts a transient current on the led. when the led is turned off, the voltage on peak is pulled high very rapidly. this voltage transient is coupled through rpeak and cpeak and exerts a transient current in the opposite direction on the led. the transient current amplitude and rc decay are calculated approximately by: peak current (amps): vcc / (rpeak+3.8) decay (seconds): cpeak*(rpeak+3.8) typical value for cpeak and rpeak at 3.3v operation are: cpeak = 20 pf rpeak = 10 ohm 3500ppm 7000ppm
i7110 page 10 ? 2005 icreate technologies corporation apd-8011-001 led clamping, laser driving since most leds exhibit a longer ? turn off ? time than ? turn on ? time, a clamping function is included on the i7110 in order to reduce the ? turn off ? time. and the function is enabled by simply connecting pin vddc to vcc. the disadvantage of clamping is that the led ? s internal capacitance must be fully charged again before the led starts to emit light. this will delay the turn on time of led especially when led drive current is low. use of peaking function will reduce the ? turn on ? delay. the combination of peaking and clamping results in very fast ? turn on ? and ? turn off ? speed for the led. when driving lasers, it will often be helpful to disable this clamping. this can be achieved by leaving the vddc connections floating. led drive pulse width adjustment (pwa) the input signal pulse width can be adjusted before the output stage. the differential voltage on the pwa pins shapes the input pulse continuously over a ? 500ps to +500ps range. the maximum difference between pwap and pwan is 1v. pwap and pwan will settle at a voltage equal to (0.76*vcc) if left floating. it is recommended that adjustment be implemented by pull down resistors on pwap and pwan. however it is common for one or other pin to be tied to ground for maximum adjustment.
i7110 ? 2005 icreate technologies corporation page 11 apd-8011-001 5 typical application circuits 5.1 qssop16 application circuit c4 0.01uf vcc r4 rn r5 rp din- din+ r6 rset2 r8 rset1 c6 10nf vcc c6 0.1uf c5 0.1uf c3 0.01uf rn & rp : pu lse width adjustment. rest2 : temperature c ompensation adjustment. typical c1=10pf ; r2=100 ohm @5v. typical c1=20pf ; r2=0 ohm @3v. undershoot / overshoot can be optimized by c1 & r2. rest1 : set nominal led drive current. u1 i7110_qsop16 pwan 1 pwap 2 dinp 3 dinn 4 vref 5 rest2 6 rest1 7 vdda 8 gnd 16 disa 15 ioutb 14 iout 13 iout 12 peak 11 vddc 10 vddd 09 r1 22r vcc d1 led r2 c1 c2 0.1uf vcc figure 13.
i7110 page 12 ? 2005 icreate technologies corporation apd-8011-001 5.2 tssop20 application circuit rn & rp : pulse width adjustment. c4 0.01uf vcc r4 rn r5 rp din- din+ r6 rset2 r8 rset1 c6 10nf vcc c6 0.1uf c5 0.1uf c3 0.01uf typical c1=10pf ; r2=100 ohm @5v. typical c1=20pf ; r2=0 ohm @3v. undershoot / over shoot can be optim ized by c1 & r2. rest1 : set nominal led drive current. rest2 : tempera ture compensati on adjustment. r1 22r vcc d1 led r2 c1 c2 0.1uf vcc u1 i7110_tssop20 pwan 2 pwap 3 dinp 4 dinn 5 vref 6 rest2 7 rest1 8 vdda 9 gnd 19 disa 18 ioutb 17 iout 16 iout 15 peak 14 vddc 13 vddd 12 nc 1 nc 10 nc 11 nc 20 figure 14
i7110 ? 2005 icreate technologies corporation page 13 apd-8011-001 6 package outline 6.1 package outline - 16-pin qsop
i7110 page 14 ? 2005 icreate technologies corporation apd-8011-001 6.2 package outline ? 20-pin tssop
i7110 ? 2005 icreate technologies corporation page 15 apd-8011-001 icreate technologies corporation no. 6, technology rd. v, science-based industrial park, hsinchu, taiwan 30077, r.o.c. tel: +886-3-579-0000 fax: +886-3-579-0077

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