LASER DIODE CONTROLLER WITH APC FEATURES SY88905 DESCRIPTION ■ DC bias current adjustable to 25mA ■ Buffered Loss-of-Signal output when used with SY88903 ■ Monitor Diode power control circuit ■ Designed for use with SY88902 and SY88903 ■ Single power supply ■ Available in 10-pin (3mm) MSOP The SY88905 is an integrated Laser Diode controller for the SY88902 Laser Driver and SY88903 Laser Receiver that provides power control functions for a complete module solution. The SY88905 is designed to provide the laser diode with an independent DC threshold current (IBIAS) source to assure optimum laser diode performance. The SY88905 also provides buffered Loss-of-Signal (LOS) output in PECL level. The device is designed for fast and accurate calibration of the laser diode. Once the optimal operating point is determined and set for a specific laser diode, the threshold current (IBIAS) is designed to automatically compensate for laser diode aging and module temperature. PIN CONFIGURATION LOSIN 1 10 VREF LOSOUT 2 APPLICATIONS 9 IBIAS SET MSOP K10-1 GND 3 8 IBIAS FB IBIAS 4 7 IPIN SET VCC 5 6 MD ■ ■ ■ ■ ■ Controller for High Speed Optical Data Transmission 1.25Gbps Gigabit Ethernet 531 Mbps and 1062Mbps Fibre Channel 622Mbps SONET Gigabit Interface Converter BLOCK DIAGRAM LOSOUT IBIAS MD VREF2 LOSIN 40X + VREF 2 VCC GND VREF IBIAS SET IBIAS FB IPIN SET Rev.: B 1 Amendment: /1 Issue Date: July 2000 SY88905 Micrel PIN DEFINITIONS Pin Type Description VCC Power Positive Power supply GND Power Ground LOSIN TTL Input Loss-of-Signal Input from SY88903 VREF Analog Output Reference Voltage IPIN SET Analog Input Adjustable, Resistor to VREF sets Monitor Diode Photo Current Reference LOSOUT PECL Output Loss-of-Signal PECL output IBIASFB Analog Output Monitor Diode Feedback IBIASSET Analog Input Adjustable, Resistor to VREF sets the DC bias current for the Laser Diode MD Analog Input Monitor Diode Connection IBIAS Analog Input DC bias current for the Laser Diode ABSOLUTE MAXIMUM RATINGS(1) LOGIC DIAGRAM Symbol Rating Value Unit VCC Power Supply Voltage 0 to +7.0 V LOSIN Input Voltage 0 to VCC V LOSOUT, IPIN SET IBIASFB, IBIAS SET Others; I/O Voltage –0.3, VCC +0.3 V TA Operating Temperature Range 0 to +85 ˚C Tstore Storage Temperature Range –55 to +125 ˚C IPIN SET, IBIAS SET, IMD Max. Sink Current 1 mA IBIASFB Max. Source Current 1 mA IBIAS Max. Sink Current 30 mA IVREF Max. Source Current 2 mA 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. 100H ECL DC ELECTRICAL(1) VCC = +5V ±10% TA = 0°C Symbol Parameter Min. Max. TA = +25°C Min. Max. TA = +85°C Min. Max. Unit Condition VOH Output HIGH Voltage VCC – 1025 VCC – 880 VCC – 1025 VCC – 880 VCC – 1025 VCC – 880 mV 50Ω to VCC–2V VOL Output LOW Voltage VCC –1810 VCC –1620 VCC –1810 VCC –1620 VCC –1810 VCC–1620 mV 50Ω to VCC–2V NOTE: 1. 100H circuits are designed to meet the DC specifications shown in the table where transverse airflow greater than 500lfpm is maintained. 2 SY88905 Micrel DC ELECTRICAL CHARACTERISTICS VCC = +5V ±10% TA = 0°C Symbol TA = +85°C Min. Typ. Max. Min. Typ. Max. ICC Power Supply Current — — 40 — 28 40 — — 40 mA IBIAS SET IBIAS SET Input Current — — 0.9 — — 0.9 — — 0.9 mA IBIAS IBIAS Output Current 0.5 — 25 0.5 — 25 0.5 — 25 mA ABIAS IBIAS Current Gain 28 — 44 28 37 44 28 — 44 VREF Reference Voltage 2.30 — 3.30 2.30 2.75 3.30 2.30 — 3.30 V IREF = -100µA ∆VPIN SET VPIN SET Voltage Tracking 0.95 — 1.35 0.95 1.13 1.35 0.95 — 1.35 V =VREF – VPIN SET ∆VBIAS SET VBIAS Voltage Tracking 0.8 — 1.20 0.8 1.0 1.20 0.8 — 1.20 V =VREF – VBIAS SET VCOMP BIAS Compliance Voltage 0.1 — 1.0 0.1 0.4 1.0 0.1 — 1.0 V IBIAS = 15mA Feedback Current(1) 350 — — 350 500 — 350 — — µA Feedback Gain(2) 4 — 14 4 — 14 4 — 14 IBIAS FB ABIAS FB Parameter TA = +25°C Min. Typ. Max. Unit Conditions No output load =IBIAS / IBIAS SET NOTE: 1. |IMD – IPIN SET| = 100µA 2. |IBIAS FB| / |IMD – IPIN SET| TTL DC ELECTRICAL CHARACTERISTICS VCC = +5V ±10% TA = 0°C Symbol Parameter TA = +25°C TA = +85°C Min. Max. Min. Max. Min. Max. Unit Condition VIH Input HIGH Voltage 2.0 — 2.0 — 2.0 — V — VIL Input LOW Voltage — 0.8 — 0.8 — 0.8 V — IIH Input HIGH Current — — 20 100 — — 20 100 — — 20 100 µA VIN = 2.7V VIN = VCC IIL Input LOW Current — –0.3 — –0.3 — –0.3 mA VIK Input Clamp Voltage — –1.2 — –1.2 — –1.2 V VIN = 0.5V IIN = –12mA NOTE: 1. Individual product specifications over-ride general specifications. DETAILED DESCRIPTION The SY88905 is an integrated control circuit for laser diode modules intended for high-frequency fiber-optic applications. The device is designed to operate with the SY88902 laser diode driver providing Automatic Power Control (APC) which provides bias current control and monitor diode interface. The device also interfaces with the SY88903 high-speed limiting amplifier providing chatter-free Loss of Signal function. Monitor Diode The MD pin on the SY88905 provides low frequency light intensity, laser power out feedback from the monitor diode in the laser diode package. This feedback is used to adjust the IBIAS level through the Automatic Power Control circuit to maintain a near constant power output from the laser diode. Laser Diode Supply Current The SY88905 provides the adjustable drive current for the laser diode, DC bias. 3 SY88905 Micrel SIMULATION GRAPHS IBIAS vs IBIAS SET 3.5E-02 3.0E-02 2.5E-02 IBIAS (A) 2.0E-02 1.5E-02 1.0E-02 5.0E-03 0.0E+00 0.E+00 1.E-04 2.E-04 3.E-04 4.E-04 5.E-04 6.E-04 7.E-04 8.E-04 IBIAS SET (A) Figure 1. IBIAS v. IBIAS SET IBIAS vs RBIAS SET 3.00E-02 2.50E-02 IBIAS (A) 2.00E-02 1.50E-02 1.00E-02 5.00E-03 0.00E+00 1.00E+03 1.00E+04 RBIAS SET (Ohm) Figure 2. IBIAS v. RBIAS SET 4 1.00E+05 SY88905 Micrel SIMULATION GRAPHS IPIN vs IPINSET 6.E-04 5.E-04 3.E-04 2.E-04 1.E-04 0.E+00 0.E+00 1.E-04 2.E-04 3.E-04 4.E-04 5.E-04 IPIN SET (A) Figure 3. IPIN v. IPIN SET IPIN SET vs RIPIN SET 7.00E-04 6.00E-04 5.00E-04 IPIN SET (A) IPIN (A) 4.E-04 4.00E-04 3.00E-04 2.00E-04 1.00E-04 0.00E+00 1.00E+03 1.00E+04 RIPIN SET (A) Figure 4. IPIN SET v. RPIN SET 5 1.00E+05 6.E-04 SY88905 Micrel SIMULATION GRAPHS V IPIN SET vs IPIN SET 2 1.8 1.6 V IPIN SET (V) 1.4 1.2 1 0.8 0.6 0.4 0.2 0 0.00E+00 1.00E-04 2.00E-04 3.00E-04 4.00E-04 5.00E-04 6.00E-04 IPIN SET (A) Figure 5. V IPIN SET v. IPIN SET Typical Vbiasset Voltage Tracking Vref - Vbiasset (V) 1.1 1.05 1 0.95 0.9 0 40 80 Junction Temperature (deg C) Figure 6. Typical VBIAS SET Voltage Tracking 6 120 SY88905 Micrel SIMULATION GRAPHS Typical VPIN SET Voltage Tracking VREF - VBIAS SET (V) 1.25 1.20 1.15 1.10 1.05 0C 40C 80C 120C Junction Temperature (deg C) Figure 7. Typical VPIN SET Voltage Tracking IBIAS FB vs IMD - IPIN SET (IPIN SET =100 uA) 0.0006 0.0004 IBIAS FB (A) 0.0002 0 -0.0002 -0.0004 -0.0006 -1.50E-04 -1.00E-04 -5.00E-05 0.00E+00 5.00E-05 IMD - IPIN SET (A) Figure 8. IBIAS FB VS. IMD - IPIN SET PRODUCT ORDERING CODE Ordering Code Package Type Operating Range SY88905KC K10-1 Commercial SY88905KCTR K10-1 Commercial 7 1.00E-04 1.50E-04 SY88905 Micrel APPLICATION EXAMPLE FOR 3-CHIP SET SOLUTION Gigabit EthernetTerminal +TX_DAT –TX_DATA RX_LOS +RX_DAT –RX_DAT LOSOUT EN DOUT DOUT DIN DIN PECL VCC VEE VCC REXT OUT VREF DIN DIN VBB VLVL OUT RSER IBIAS VCC VCC MD IPIN SET VPIN SET VREF SY88905 RSET VREF SY88902 EN LOSIN LOS SY88903 VCC VEE Laser Module VCC GND IBIAS SET VBIAS SET IBIAS FB IBIAS SET VREF 8 SY88905 Micrel 10 LEAD MSOP (K10-1) Rev. 00 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 9