UX 2222 155Mbps to 2Gbps Laser Driver General Description Features The UX2222 is a complete CMOS laser driver for SFP/SFF applications from 155Mbps to 2Gbps.It is fully compliant with the SFP MSA timing and the SFF-8472 transmit diagnostic requirements. The UX2222 consists of an automatic power control (APC) feedback loop, a reference voltage generator with temperature compensation and a safety-logic circuit. The UX2222 provides complementary output currents. The APC feature allows an optical transmitter to maintain constant Single +3.3V Power Supply Automatic Average Power Control (APC) Modulation Compensation Fully Compliant with SFP and SFF-8472 MSA 100mA Bias Current 85mA Modulation Current Rise and Fall Times less than 250ps Apply to FP、DFB、VCSEL Laser Pin Configuration average optical power by a monitor photodiode, despite changes in laser threshold current over temperature and lifetime. Optional temperature compensation extinction compensates ratio change with Laser Diode temperature. External resistors set the require laser current level. The UX2222 also provides transmit-disable control (TX_DISABLE), a single-point latched transmit-failure monitor output (TX_FAULT), photocurrent monitoring, and bias-current monitoring to indicate faults. Figure 1. Pin Configuration QFN 24 Typical Application Circuit Figure 2. Typical Application Circuit 2007 Preliminary Datasheet www.uxfastic.com 1 UX 2222 155Mbps to 2Gbps Laser Driver Pin Description Pin No. Name 1 MODTC 2,5,14,17 VCC +3.3V Power Supply Voltage 3 INP Noninverted data input 4 INN Inverted data input 6 TX_DISABLE 7 PC_MON 8 BC_MON 9 SHUTDOWN 10,12 GND 11 TX_FAULT 13 BIAS Laser Bias-Current Output 15 OUTN Inverted Data Output 16 OUTP Data Output 18 MD 19 APCFILT1 Connect a capacitor(CAPC) between pin19(APCFILT1) and pin20(APCFILT1) to set the time constant of the APC feedback loop 20 APCFILT2 (See pin 19) 21 APCSET A resistor connected from this pin to ground sets the desired average optical power 22 MODSET A resistor connected from this pin to Ground 23 RE 24 RTTH 2007 Preliminary Datasheet Function Connecting a resistor between this pin and ground sets the temperature coefficient of IMOD when temperature is higher than the threshold set by Rtth Transmitter Disable, TTL. Laser output is disabled when DISABLE is asserted high or left unconnected. The laser output is enabled when this pin is asserted low Photodiode-current Monitor Output. Current out of this pin develops a ground referenced voltage across an external resistor that is proportional to the monitor-diode current Bias-current Monitor Output. Current out of this pin develops a ground referenced voltage across an external resistor that is proportional to the bias current Shutdown Driver Output, Voltage output to control an external transistor for optional shutdown circuitry Ground Open-Collector Transmit Fault indicator Photodiode feedback input pin Connecting a resistor between this pin and ground sets the coefficient of IMOD by temperature. Leave open for zero-coupling Threshold temperature compensation. A resistor at this pin programs the temperature above which compensation is added to the modulation current optional www.uxfastic.com 2 UX 2222 155Mbps to 2Gbps Laser Driver Absolute Maximum Ratings Symbol VCC TA TSTG Parameter Rating Units 4 V Operating ambient -40 to +85 °C Storage temperature -65 to +150 °C Power Supply (VCC-GND) DC Characteristics Symbol Parameter IBIAS Range of Programmable Laser Bias Current Vin Total Differential Input Signal VMD The dc Voltage of Input Min. Typ. Max. Units 100 mA 2400 mV 200 0.6 VCC V RBC_MON IBIAS/IBC_MON 80 mA / mA RPC_MON IMD/IPC_MON 1 mA / mA TTH Threshold-Setting Range for Temperature Compensate -20 +80 °C Re IMOD Compensation-Setting Range by IBIAS 0 1.5 mA / mA IMD Monitor-Diode Input Current Range 20 2000 uA VHI TX_DISABLE Input High 2.0 VLO TX_DISABLE Input Low 0.8 V VOL FAILOUT Output Low 0.4 V Shutdown Output High V V VCC-0.4 Shutdown Output Low V 0.4 AC Characteristics (RLOAD (at OUTP and OUTN) = 25Ω connected to VCC, Typical values are at VCC = +3.3V and TA = +25°C.) (Note 1) Symbol Parameter Range of IMOD Programmable Modulation Current TR, TF Modulation-Current Rise and Fall Time 2007 Preliminary Datasheet Conditions Min. Typ. Minimum differential input swing is 200mVp-p (Note 2) Max. Units 85 mA 250 ps IBIAS = 20mA, IMOD = 40mA, 2.5ns unit interval; measured 150 from 20% to 80% www.uxfastic.com 3 UX 2222 155Mbps to 2Gbps Laser Driver TPWD Modulation-Current IBIAS = 20mA, IMOD = 40mA, Pulse-Width Distortion 5ns period 25 BIAS and Modulation Turn-on Delay ps 100 us Max. Units Note 1: AC characteristics are guaranteed by design and characterization. Note 2: An 200mVp-p differential is equivalent to complementary 10mVp-p signals on VINP and VINN. Transmit diagnostic Characteristics Symbol Parameter Time to initialize, T_init including reset of TX_Fault TX_Fault TX_Fault Assert Time Conditions Min. From power on or negation of TX_Fault using TX_Disable Time from fault to TX_Fault on. Typ. 21 ms 250 ns 45 us 350 ns Time from falling edge of T_on TX_Disable Negate TX_Disable to when the Time modulated optical output rises above 90% of nominal Time from rising edge of T_off TX_Disable Assert Time TX_Disable to when the optical output falls below 10% of nominal T_reset TX_Disable to reset 2007 Preliminary Datasheet TX_Disable must be held high to reset TX_fault www.uxfastic.com 10 us 4 UX 2210 155Mbps to 2Gbps Laser Diode Driver Package Information Figure 6. QFN24 Package 2006 Preliminary Datasheet www.uxfastic.com 5