SY88216L 3.3V, 2.5Gbps Burst Mode Laser Driver General Description Features The SY88216L is a single supply 3.3V burst mode laser driver for A-PON, B-PON, EPON, GE-PON, and G-PON applications with data rates from 155Mbps up to 2.5Gbps. The driver can deliver modulation current up to 85mA, and provides a high compliance voltage that makes it suitable for high-current operation with the laser DC-coupled to it. All support documentation can be found on Micrel’s web site at: www.micrel.com. • • • • • • • • • 2.4V minimum laser compliance voltage Operation up to 2.5Gbps Fast burst mode enable/disable delay Modulation current up to 85mA Bias current up to 70mA Infinite bias current hold time between bursts Safety features Power monitoring Available in 24-pin (4mm x 4mm) QFN package Applications • Multi-rate burst mode applications: A-PON, B-PON, G-PON, E-PON, GE-PON Markets • Fiber-to-the-Premises (FTTP): Fiber-to-the-Home (FTTH), Fiber-to-the-Business (FTTB) • FTTC (Fiber-to-the-Curb) ___________________________________________________________________________________________________________ Typical Application Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com July 2008 M9999-071108-C [email protected] or (408) 955-1690 Micrel, Inc. SY88216L Ordering Information(1) Part Number SY88216LMG (2) SY88216LMGTR Package Type Operating Range Package Marking Lead Finish QFN-24 Industrial 216L with Pb-Free bar-line indicator NiPdAu Pb-Free QFN-24 Industrial 216L with Pb-Free bar-line indicator NiPdAu Pb-Free Notes: 1. Contact factory for die availability. Dice are guaranteed at TA = +25°C, DC Electrical only. 2. Tape and Reel. Pin Configuration 24-Pin QFN July 2008 2 M9999-071108-C [email protected] or (408) 955-1690 Micrel, Inc. SY88216L Pin Description Pin Number Pin Name Pin Function 2 DIN+ Non-inverting input data. Internally terminated with 50Ω to a reference voltage. 3 DIN- Inverting input data. Internally terminated with 50Ω to a reference voltage. 5 BEN+ Non-inverting burst enable. Accepts any input, single-ended or differential: TTL/CMOS, LVPECL, CML, LVDS, HSTL, and SSTL. BEN requires an external termination. See Figure 2. 6 BEN- Inverting burst enable. Accepts any input, single-ended or differential: TTL/CMOS, LVPECL, CML, LVDS, HSTL, and SSTL. BEN requires an external termination. See Figure 2. 7 /EN Active low TTL/CMOS. Internally pulled-up. Pull-down with a 22kΩ or lower resistance or apply a low level signal (<0.8 V) to enable bias and modulation. Keep floating or apply a high level (>2 V) to disable. 9 OSC Internal oscillator setting option. Install a 0Ω resistor from this pin to VCC or leave it open to set the frequency. Refer to the frequency table. 10 /APCFAULT 12 PWRMON Indicates APC failure when low. Active low TTL/CMOS. Power Monitor. Provides a current which is proportional to the sum of bias current and half of modulation current. Install a resistor between this pin and GND to convert that current to a voltage. 13 BIAS- Inverting laser bias current output. Pull-up to VCC with a resistor. 14 BIAS+ Non-inverting laser bias current output, sources current when BEN is high. Connect to the cathode of the laser through a resistor. 16 MOD+ Non-inverted modulation current output. Provides modulation current when input data is positive. 17 MOD- Inverted modulation current output. Provides modulation current when input data is negative. 20 MD Input from the laser monitoring photodiode. Connect to the anode of the photodiode for APC operation. 22 BIASMAX Install a resistor between this pin and GND to set the maximum bias current for the closed loop operation. The APC loop controls the bias current up to the level of BIASMAX. When the bias current reaches the maximum value set through this pin, the driver continues to sink a current equal to this maximum. For open loop operations, this pin sets the bias current. 23 MODSET Modulation current setting and control. The modulation current is set by installing an external resistor from this pin-to-ground or using a current source. 24 APCSET Bias current setting and control. The bias current is set by installing an external resistor from this pin to ground or using a current source. Connect a 50K resistor-to-GND for open loop operation. 8, 11,19 GND Ground. Ground and exposed pad must be connected to the plane of the most negative potential. 1, 4, 15, 18, 21 VCC Supply Voltage. Bypass with a 0.1µF//0.01µF low ESR capacitor as close to VCC pin as possible. Truth Table Oscillator Frequency DIN+ DIN- /EN L H L H L X X MOD+ (1) MOD- Laser (2) Output H L L L L H H H H L L OSC Frequency (MHz) Open 25 VCC 50 Notes: 1. IMOD = 0 when MOD+ = H. 2. Assuming that the laser is tied to MOD+. July 2008 3 M9999-071108-C [email protected] or (408) 955-1690 Micrel, Inc. SY88216L Absolute Maximum Ratings(1) Operating Ratings(2) Supply Voltage (VCC) .................................... –0.5V to +4.0V CML Input Voltage (VIN) ....................VCC–1.2V to VCC+0.5V TTL Control Input Voltage (VI)..................... 0V to VCC+0.3V Lead Temperature (soldering, 20sec.) ..................... +260°C Storage Temperature (Ts) ......................... –65°C to +150°C Supply Voltage (VCC) .................................... +3.0V to +3.6V Ambient Temperature (TA) .......................... –40°C to +85°C (3) Package Thermal Resistance QFN (θJA) Still-air ........................................................ 75°C/W (ψJB) ................................................................... 30°C/W DC Electrical Characteristics TA = –40°C to +85°C and VCC = +3.0V to +3.6V. Unless otherwise noted, typical values are VCC = +3.3V, TA = 25°C, IMOD = 25mA, IBIAS = 20mA. Symbol Parameter Condition ICC Power Supply Current Modulation and Bias currents excluded Min Typ VMOD_MIN Minimum Voltage Required at the Driver Output, MOD+ and MOD-, for Proper Operation 0.6 V VBIAS_MIN Minimum Voltage Required at the Driver Output, BIAS+ and BIAS-, for Proper Operation 0.8 V IBIAS Bias-ON Current Voltage at Bias pin ≥ 0.8V IBIAS_OFF Bias-OFF Current Current at BIAS pin when /EN is high or BEN is low RIN Input Resistance at DIN+ and DIN- Single ended VDIFF-IN (DIN) Differential Input Voltage Swing 55 1 42.5 50 100 Max 95 (4) Units mA 70 mA 150 µA 57.5 Ω 2400 mVPP VIL (/EN) /EN Input Low VIH (/EN) /EN Input High 0.8 V VOL /APCFAULT Output Low IOL = 2mA IOH /APCFAULT Output Leakage VOH = VCC BEN+, BEN- Burst Mode Enable Signal Single Ended VIH (BEN) High Voltage BEN+, BEN- VIL (BEN) Low Voltage BEN+, BEN- -0.3 V VIN (BEN) Input Voltage Swing BEN+, BEN- 100 mV VDIFF-IN (BEN) Differential Input Voltage Swing BEN+, BEN- 200 mVPP VPWRMON Maximum Voltage at PWRMON Pin 1.25 V IMD Current Range at MD Pin 2 V 0.5 V 100 µA 0.8 V VCC + 0.3 50 1500 V µA Notes: 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 ratings conditions for extended periods may affect device reliability. 2. The data sheet limits are not guaranteed if the device is operated beyond the operating ratings. 3. Package Thermal Resistance assumes exposed pad is soldered (or equivalent) to the devices most negative potential on the PCB. ψJB uses a 4-layer and θJA in still air unless otherwise stated. 4. ICC = 95mA for worst-case conditions with IMOD = 85mA, IBIAS = 70mA, TA = +85°C, VCC = 3.6. July 2008 4 M9999-071108-C [email protected] or (408) 955-1690 Micrel, Inc. SY88216L AC Electrical Characteristics TA = –40°C to +85°C and VCC = +3.0V to +3.6V. Unless otherwise noted, typical values are VCC = +3.3V, TA = 25°C, IMOD = 25mA, IBIAS = 20mA. Symbol IMOD IMOD_OFF Parameter Condition Data Rate NRZ (5) Modulation Current Modulation OFF Current tr Output Current Rise Time tf Output Current Fall Time Jitter tINIT (7) Total Jitter APC Loop Initialization Time Min Units 0.155 2.5 Gbps 10 85 mA DC-coupled, Voltage at MOD Pin ≥0.6V 10 (6) mA Current at MOD+ when /EN is High or BEN is High 150 µA Current at MOD- when /EN is High or BEN is Low 150 µA 70 20% to 80%, IMOD = 60mA 60 85 ps 20% to 80%, IMOD = 60mA 60 85 ps 155Mbps 30 622Mbps 30 1.25Gbps 30 2.5Gbps 30 Power up with /En Low and BEN High 12 µs /EN Changes from High to Low with Power ON and BEN High 10 µs BEN Changes from Low to High with Power ON and /EN Low 2.5 ns 2.5 ns 2 ns (8, 9) (8, 10) Burst Disable Delay Burst OFF-Time Max AC-coupled Burst Enable Delay Burst ON-Time Typ psPP 155Mbps 1.9 µs 622Mbps 720 ns 1.25Gbps 576 ns 2.5Gbps 576 ns 155Mbps 1.9 µs 622Mbps 720 ns 1.25Gbps 576 ns 2.5Gbps 576 ns Notes: 5. Load = 15Ω. 6. Assuming VCC = 3.0V, Laser bandgap voltage = 1V, laser package inductance = 1nH, laser equivalent series resistor = 5 Ω, and damping resistor = 10Ω. 7. Total jitter is measured using 27 – 1 PRBS pattern. 8. Measured with a laser equivalent resistive load. 9. Burst Enable Delay is measured as the time between the instant when the BEN+ signal going from low to high reaches 50% of its amplitude and the instant at which the modulation current or the bias current (whichever takes longer) reaches 90% of its final value. 10. Burst Disable Delay is measured as the time between the instant when the BEN+ signal going from high to low reaches 50% of its amplitude and the instant at which the modulation current or the bias current (whichever takes longer) goes below 10% of its final value. July 2008 5 M9999-071108-C [email protected] or (408) 955-1690 Micrel, Inc. SY88216L Functional Diagram July 2008 6 M9999-071108-C [email protected] or (408) 955-1690 Micrel, Inc. SY88216L APC Loop Function At start up, with the driver enabled and burst mode enabled, the laser turns ON within a few microseconds and its back facet monitoring photodiode starts to generate a photocurrent proportional to the optical power. The photocurrent is fed back to the MD pin on the driver where it’s converted to a voltage. The conversion voltage is compared to APCSET on the driver. At equilibrium, the feedback voltage equals the APCSET voltage and the laser optical power reaches its nominal value. If the laser power deviates from its nominal value, the APC loop brings it back to its nominal setting. After everything is settled to its nominal value and the BEN changes from high to low to disable the burst mode, the instantaneous bias current value is latched until BEN switches from low to high again. Then the bias and modulation output stages turn ON and the bias stays equal to the stored value until the feedback from the monitoring photodiode reaches the APCSET value and the APC closed loop starts to regulate the laser power. Detailed Functional Description The SY88216L burst mode laser driver is comprised from a fast modulator, a fast bias circuit, and a digital APC loop that allows for fast laser turn-ON time. The modulator is comparable to a fast continuous mode modulator that turns ON in the nanosecond range. The bias circuit has a differential pair at the output to allow for fast turn-ON time. Both modulator and bias differential pairs can be enabled for burst operation by applying a high level signal at BEN+ pin and a low level signal at BEN- pin. The driver features a power monitoring function. BIAS and Modulation Setting Bias and modulation currents are set by installing resistors from APCSET (pin24)-to-ground and from MODSET (pin23)-to-ground respectively or by applying a negative current at those pins. IBIAS variation versus RAPCSET resistor, IBIAS variation versus RBIASMAX resistor, and IMOD variation versus RMODSET resistor are shown on Page 8. APC Loop Failure The APCFAULT is asserted Low if the bias current reaches BIASMAX or if the APC loop counter reaches its minimum or its maximum counts. BIASMAX A resistor between the BIASMAX pin and ground sets the maximum bias the driver can sink. At normal operation, the bias current tracks the laser optical power through the laser monitoring photodiode and the APC loop to compensate for any power deviation from the nominal value set at the start of operation using APCSET. If any failure occurs (laser or photodiode degradation, open feedback circuit etc.) the APC loop keeps increasing the bias current in an effort to compensate for the low power indication, the bias current will then stop increasing when it reaches BIASMAX value and continue to operate at that maximum value and APCFAULT asserted. BIASMAX also controls the bias current when the circuit is operating in the open loop mode. July 2008 Interfacing the Driver with the Laser Diode As shown on the “Typical Application” drawing, MOD+ pin is connected to the laser cathode through a 10Ω resistor and MOD- pin is connected to VCC with a 15Ω resistor equivalent to 10Ω (damping resistor) in series with the laser (equivalent resistor of 5Ω). The laser can be driven differentially by connecting MOD- to the anode of the laser through 15Ω (15Ω pull-up removed) and isolating the anode of the laser from VCC with an inductor. To meet the stringent laser turn-ON time, per BPON/GPON/EPON spec, the bias (BIAS+ pin) must be connected to the cathode of the laser through a resistor not an inductor as in continuous mode. BIAS- pin is pulled-up to VCC. 7 M9999-071108-C [email protected] or (408) 955-1690 Micrel, Inc. SY88216L Typical Characteristics July 2008 8 M9999-071108-C [email protected] or (408) 955-1690 Micrel, Inc. SY88216L Functional Characteristics July 2008 9 M9999-071108-C [email protected] or (408) 955-1690 Micrel, Inc. SY88216L Input and Output Stages Figure 1a. Simplified Input Stage Figure 1b. Simplified BEN Input Stage Figure 1c. Simplified Output Stage Interfacing DIN and BEN Inputs to Different Logic Drivers Figure 2a. Driving DIN and BEN with PECL Outputs Figure 2b. Driving DIN and BEN with CML Outputs Figure 2c. Driving BEN with LVTTL/LCMOS Outputs Figure 2d. Driving BEN with LVDS Outputs July 2008 10 M9999-071108-C [email protected] or (408) 955-1690 Micrel, Inc. SY88216L Package Information 24-Pin (3mm x 3mm) QFN MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer. Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale. © 2007 Micrel, Incorporated. July 2008 11 M9999-071108-C [email protected] or (408) 955-1690