SDH/SONET 2.5Gbps LASER DIODE DRIVER FEATURES ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTION Up to 2.5Gbps operation 25mA peak drive current Separate modulation control Separate output enable for laser safety Differential inputs for data 75KΩ input pulldown resistor Designed for use with SY88923, SY88904 or SY88905 Available in a tiny 10-pin (3mm) MSOP The SY88922 is a high-speed current switch for driving a semiconductor laser diode in optical transmission applications. The output current, or modulation current IMOD, is DC current controlled by IRSET, current through the resistor RSET. 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 REXT 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 SY88922 utilizes the high performance bipolar ASSET™ technology. APPLICATIONS PIN CONFIGURATIONS /EN 1 ■ ■ ■ ■ ■ 10 VCC DIN 2 /DIN 3 SY88922 9 OUT MSOP K10-1 8 /OUT VREF 4 7 GND RSET 5 6 GND 1.25Gbps Gigabit Ethernet 531Mbps and 1062Mbps Fibre Channel 622Mbps SONET Gigabit Interface Converter 2.5Gb/s SDH/SONET BLOCK DIAGRAM VCC REXT OUT OUT RSER DIN Internal Logic DIN IMOD EN BIAS Control to Laser Diode 40X VCC GND Modulation Control GND RSET VREF RSET Rev.: B 1 Amendment: /1 Issue Date: July 2000 SY88922 Micrel TRUTH TABLE(1) PIN NAMES Pin Function VCC Most positive power supply input, +5V for PECL operation. GND Ground DIN, /DIN 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. VREF Voltage reference for use with RSET. RSET An external resistor sets up the source current for modulation Imod. D D /EN OUT(2) /OUT L H L H L H L L L H X X H H L NOTES: 1. L = LOW, H = HIGH, X = don't care 2. H = IOUT = 0mA ABSOLUTE MAXIMUM RATINGS(1) Symbol Rating Value Unit VCC Power Supply Voltage 0 to +7.0 V VI Input Voltage 0 to VCC V IO Output Current TA Operating Temperature Range Tstore Storage Temperature Range Ptot Power Dissipation 25 mA 0 to +85 °C –55 to +125 °C 250 mW NOTE: 1. Permanent device damage may occur if ABSOLUTE MAXIMUM RATINGS are exceeded. This is a stress rating only and functional operation is not implied at conditions other than those detailed in the operational sections of this data sheet. Exposure to ABSOLUTE MAXIMUM RATlNG conditions for extended periods may affect device reliability. OPERATIONING CONDITIONS(1) Symbol Rating Value Unit +4.5 to +5.5 V VCC Power Supply Voltage REXT Resistor to Dissipate Power 10 to 50 Ω RSER Laser Diode Serial Resistor 0 to 50 Ω RSET Resistor to Adjust Current 1500 to 50,000 Ω 113 °C/W 2.5 typical pf ΘJA Thermal Resistance of Package to COUT Capacitance on OUT + /OUT Ambient(2) NOTES: 1. The voltage drop across REXT and RSER plus Laser Diode should not be greater than 2V. 2. Still air without heatsink. 2 SY88922 Micrel DC ELECTRICAL CHARACTERISTICS GND = 0V; VCC = +5.0V ±10%; TA = 0°C to + 85°C TA = 0°C Symbol Parameter TA = +25°C Min. Typ. Max. Min. Typ. TA = +85°C Max. Min. Typ. Max. Unit VIH Input HIGH Voltage (DIN, /DIN, /EN) VCC–1165 — VCC–880 VCC–1165 — VCC–880 VCC–1165 — VCC–880 mV VIL Input LOW Voltage (DIN, /DIN, /EN) VCC–1810 — VCC–1475 VCC–1810 — VCC–1475 VCC–1810 — VCC–1475 mV VREF Reference Voltage — 3.12 — — 3.00 — — 2.80 — V Current(1) IIL Input LOW (DIN, /DIN, /EN) 0.5 — — 0.5 — — 0.5 — — uA IIH Input HIGH Current (DIN, /DIN, /EN) — — 100 — — 100 — — 100 uA ICC Supply Current(2) — 16 25 — 16 25 — 16 25 mA IOL Output LOW Current (/EN = HIGH) — — 500 — — 500 — — 500 uA IOUT Modulation Current 5 15 25 5 15 25 5 15 25 mA IRSET Modulation Control 0.125 — 0.625 0.125 — 0.625 0.125 — 0.625 mA ARSET =IOUT/IRSET 30 38 44 30 38 44 30 38 44 — NOTES: 1. VI = VIL(Min.) 2. IMOD = 25mA. AC ELECTRICAL CHARACTERISTICS(1) IMOD =10mA; GND = 0V; VCC = +5V ±10%; TA = 0°C to + 85°C TA = 0°C Symbol Parameter TA = +25°C TA = +85°C Min. Typ. Max. Min. Typ. Max. Min. Typ. Max. Unit tpd D Propagation Delay DIN - OUT — — 1000 — 500 1000 — — 1000 ps tpd EN Propagation Delay /EN - OUT — — 1000 — 450 1000 — — 1000 ps tr tf Rise/Fall Time (20% to 80%) — — 160 — 110 160 — — 160 ps IOR Output Current Ringing(2) — — 10 — — 10 — — 10 % NOTES: 1. REXT = RSER = 25Ω ±1%, RSER connects to VCC directly without Laser Diode. 2. IOH = 5 to 25mA 3 Conditions Load = 25Ω SY88922 Micrel PERFORMANCE CURVES IO and RSET 30 25 IO (mA) 20 15 10 5 0.0 0.0 2.0K 4.0K 6.0K RSET (ohm) PRODUCT ORDERING CODE Ordering Code Package Type Operating Range SY88922KC K10-1 Commercial SY88922KCTR K10-1 Commercial 4 8.0K 10K 12K SY88922 Micrel APPLICATION EXAMPLE FOR 3-CHIP SET SOLUTION GBIC Terminal TX_DATA+ VCC DIN DIN LOSOUT EN VREF RSET 20kΩ VREF GND SY88922 VCC IBIAS GND SY88905 VCC LOS VCC OUT RSER VCC 20kΩ 20kΩ OUT MD IBIAS SET IBIAS FB IPIN SET DIN DIN 0.1µF BLM21A102S VCC Laser Module The value of RSER depends on the Laser Diode. VCC 5 24Ω LOSLVL 82Ω LOSIN EN SY88923 VREF 130Ω Laserdiode REXT 1000pF 82Ω 68Ω 82Ω Photodiode 130Ω 200Ω 130Ω TX_DATA– VCC DOUT DOUT GND 0.1µF 68Ω 82Ω ENABLE/DISABLE RX_LOS RX_DATA+ RX_DATA– VCC 20kΩ 200Ω 130Ω SY88922 Micrel 10 LEAD MSOP (K10-1) Rev. 00 6 SY88922 Micrel 7 SY88922 Micrel MICREL-SYNERGY TEL 3250 SCOTT BOULEVARD SANTA CLARA CA 95054 USA + 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 any 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 patent right of Micrel Inc. © 2000 Micrel Incorporated 8