Create i7110 300 Mbps LED Drivers Data Sheet iCreate Technologies Corporation © 2005 iCreate Technologies Corporation APD-8011-001 i7110 © Copyright 2005 iCreate Technologies Corporation Information contained in this publication is intended through suggestion only and may be superseded by updates.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 warranty 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 transmitted in any form or by any means for any purpose without the permission of iCreate. No licenses are conveyed, implicitly or otherwise, under any intellectual property rights. The iCreate logo and name are registered trademarks of iCreate Technologies Corporation. All rights reserved. All other trademarks mentioned herein are the property of their respective companies. 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V, Science-Based Industrial Park, Hsinchu, Taiwan 300 Phone +886-3-579-0000 Fax +886-3-579-0077 e-mail [email protected] Revision：3.00 Date：05/2005 © 2005 iCreate Technologies Corporation APD-8011-001 i7110 +3.3V to +5.0V, 300Mbps LED Driver 1 Introduction 1.1 General Description 1.2 Applications 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 ‘turn off’ time. A peaking and clamp circuit is implemented in i7110 to enhance speed performance and connecting external RC network performs this function. 1.3 Features 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 module, and the current is disabled if pin Disa is Pulled high. The i7110 is packaged in QSOP16 and TSSOP20. 1.4 Ordering Information FDDI SDH STM-1 SONET OC-3 Fast Ethernet Fiber Channel 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. 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 © 2005 iCreate Technologies Corporation Page 1 APD-8011-001 i7110 2 Pin Configuration and Definition 2.1 Pin Configuration TSSOP20 QSOP16 NC NC PWAN GNDA PWAN GNDA PWAP DINP DINN DISA PWAP DISA IOUTB IOUTB IOUT IOUT DINP DINN VREF RSET2 PEAK RSET2 PEAK RSET1 VDDC RSET1 VDDC VDDA VDDD VDDA NC VDDD NC VREF I7110-ES I7110-EP IOUT IOUT Figure 1. i7110 pin configuration Page 2 © 2005 iCreate Technologies Corporation APD-8011-001 i7110 2.2 Pin Definition TSSOP20 QSOP16 Pin No. Pin No. 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 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 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 Pin Name VDDC © 2005 iCreate Technologies Corporation Description Driver output Page 3 APD-8011-001 i7110 3 Block Diagram P W A P P W A N G N D A D IS A D IN P D IN N VREF RSET2 IO U T B P u ls e W id th A d ju s t In p u t B u ffe r D riv e r IO U T Bandgap & B ia s C irc u it C u rre n t M o d u la tio n RSET1 PEAK P e a k in g & C la m p in g VDDA VDDD VDDC Figure 2. i7110 block diagram 4 Electrical Specifications 4.1 Recommended Operating Conditions Parameter Power Supply Operating Ambient Page 4 Symbol Rating Unit VCC 3.0 to 5.5 V TA -40 to 85 ℃ © 2005 iCreate Technologies Corporation APD-8011-001 i7110 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 VIN_H Input high voltage level VCC-1.0 - VCC-0.8 V VIN_L Input low voltage level 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 tR LED drive rise time - 0.7 1 ns LED tF LED drive fall time - 0.7 1 ns PEAK tR Peaking current rise time - - 1 ns PEAK tF Peaking current fall time - - 1 ns IDD Supply current - ILED+10 ILED+20 mA © 2005 iCreate Technologies Corporation Page 5 APD-8011-001 i7110 4.4 Typical Operating Curve (I7110 characteristic curve tested at VCC=3.3V , 5V. IOUT, IOUTB connect 10Ω resistor to VCC, VREF is floating , DINP connects to VCC, DINN connects to GND) Modulation Current VS RSET1VCC=3.3V Figure 3 Modulation Current VS RSET1 VCC=5V Figure 4 Page 6 Modulation Current VS RSET2 VCC=3.3V Figure 5 Modulation Current VS RSET2 VCC=5V Figure 6 © 2005 iCreate Technologies Corporation APD-8011-001 i7110 4.5 Temperature Compensation Contour Plot (I7110 characteristic curve , relationship between modulation current with RSET1 & RSET2. IOUT, IOUTB connect 10Ω resistor to VCC, VREF is floating , DINP connects to VCC, DINN connects to GND ) 100000 100000 10mA RRSET2(ohm) RRSET1(ohm) 10mA 10000 40mA 60mA 10000 40mA 60mA 80mA 80mA 100mA 100mA 120mA 120mA 1000 1000 100 1000 10000 100000 100 1000 RRSET2(ohm) 10000 100000 RRSET2(ohm) Figure7. Tj = 50 degree Figure8. Tj = 75egree 100000 100000 10mA 10000 40mA 60mA RRSET1(ohm) RRSET1(ohm) 10mA 10000 40mA 60mA 80mA 80mA 100mA 100mA 120mA 120mA 1000 1000 100 1000 10000 100000 100 1000 RRSET2(ohm) 10000 100000 RRSET2(ohm) Figure 9. Tj = 100degree © 2005 iCreate Technologies Corporation Figure 10 Tj = 125 degree Page 7 APD-8011-001 i7110 4.6 Detail Description The VREF is used to simplify the PECLcompatible 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. 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. LED Drive and Temperature 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. Reference-Voltage Generate The reference-voltage generator circuit provides single-ended input reference voltage VREF. PW AP PW AN D IN P In p u t B u ffe r GND D IS A GND IO U T B P u ls e w id th A d ju s t D riv e r IO U T D IN N RPEAK Bandgap CPEAK VREF RSET2 C u rre n t M o d u la tio n PEAK P e a k in g & C la m p in g RRSET2 RSET1 VDDA VDDD VDDC RRSET1 Figure-11 Page 8 © 2005 iCreate Technologies Corporation APD-8011-001 i7110 7000ppm 3500ppm 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 © 2005 iCreate Technologies Corporation floating. Two external components 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 Page 9 APD-8011-001 i7110 LED Clamping, Laser Driving Continuously over a –500ps to +500ps range. 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 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. 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 Page 10 © 2005 iCreate Technologies Corporation APD-8011-001 i7110 5 Typical Application Circuits 5.1 QSSOP16 Application Circuit U1 R4 Rn 1 R5 Rp 2 3 DIN+ 4 DINC6 10nF 5 6 R6 Rset2 7 VCC R8 Rset1 8 C4 C5 0.01uF 0.1uF PWAN GND PWAP DISA DINP IOUTB DINN IOUT VREF IOUT REST2 PEAK REST1 VDDC VDDA VDDD 16 15 VCC VCC C6 0.1uF R1 22R D1 LED 14 13 12 10 09 C1 R2 11 VCC C2 0.1uF C3 0.01uF i7110_QSOP16 undershoot / overshoot can be optimized by C1 & R2. Typical C1=20pF ; R2=0 ohm @3V. Typical C1=10pF ; R2=100 ohm @5V. Rest2 : Temperature compensation adjustment. Rest1 : Set nominal LED drive current. Rn & Rp : Pulse width adjustment. Figure 13. © 2005 iCreate Technologies Corporation Page 11 APD-8011-001 i7110 5.2 TSSOP20 Application Circuit U1 1 R4 Rn R5 Rp 2 3 4 DIN+ 5 DINC6 10nF 6 7 R6 Rset2 VCC R8 Rset1 8 9 C4 C5 0.01uF 0.1uF 10 NC NC PWAN GND PWAP DISA DINP IOUTB DINN IOUT VREF IOUT REST2 PEAK REST1 VDDC VDDA VDDD NC NC 20 19 18 VCC VCC C6 0.1uF R1 22R D1 LED 17 16 15 13 12 C1 R2 14 VCC C2 0.1uF C3 0.01uF 11 i7110_TSSOP20 undershoot / overshoot can be optimized by C1 & R2. Typical C1=20pF ; R2=0 ohm @3V. Typical C1=10pF ; R2=100 ohm @5V. Rest2 : Temperature compensation adjustment. Rest1 : Set nominal LED drive current. Rn & Rp : Pulse width adjustment. Figure 14 Page 12 © 2005 iCreate Technologies Corporation APD-8011-001 i7110 6 Package Outline 6.1 Package Outline - 16-pin QSOP © 2005 iCreate Technologies Corporation Page 13 APD-8011-001 i7110 6.2 Package Outline – 20-pin TSSOP Page 14 © 2005 iCreate Technologies Corporation APD-8011-001 i7110 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 © 2005 iCreate Technologies Corporation Page 15 APD-8011-001