FIBER OPTIC MODULE CONTROLLER WITH APC Micrel, Inc. DESCRIPTION FEATURES ■ DC bias current adjustable to 25mA ■ Buffered Loss-of-Signal output when used with SY88903 ■ Controlled laser diode turn on ■ Laser diode over-current detect ■ Monitor diode power control circuit ■ Laser diode driver enable ■ Designed for use with SY88902 and SY88903 ■ Single power supply ■ Available in 16-pin MSOP The SY88904 is an integrated controller for the SY88902 Laser Driver and SY88903 Laser Receiver that provides power control and system interface functions for a complete module solution. The SY88904 is designed to provide the laser diode with an independent DC threshold current (IBIAS) source to assure optimum laser diode performance. It has special safety features which disable the currents to the laser diode if certain faults are detected in the module. The SY88904 also provides buffered Loss-of-Signal (LOS) output in open collector level. The device is designed for fast and accurate calibration of the laser diode as well as deriving the control signals for system integration. The SY88904 provides for delayed turn on of the laser diode on system start up, chatter-free Loss-of-Signal, Low VCC detect and laser diode over-current situations. 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. APPLICATIONS ■ ■ ■ ■ ■ SY88904 SY88904 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 TTL PECL VREF 4 LOSIN TX_Out PECL II_LIMIT + TX_Fault TX_Disable Fault Detect Circuit OC MD_Low - ILIMIT SET VREF 3 + TTL IBIAS 40X MD + VCC DET VREF 2 VCC DET VCC 4.75 GND RWIN M9999-081005 [email protected] or (408) 955-1690 IBIAS SET IBIAS FB IPIN SET VREF Rev.: B 1 Amendment: /0 Issue Date: August 2005 SY88904 Micrel, Inc. PACKAGE/ORDERING INFORMATION TX_Out 1 16 VCC VREF 2 15 LOSOUT IBIAS 3 14 LOSIN ILIMIT SET 4 13 RWIN IBIAS SET 5 12 TX_Disable IBIAS FB 6 11 TX_Fault MD 7 10 VCCDET IPIN SET 8 9 GND MSOP K16-1 Ordering Information Part Number Package Type Operating Range Package Marking Lead Finish SY88904KC K16-1 Commercial 904 Sn-Pb SY88904KCTR(1) K16-1 Commercial 904 Sn-Pb SY88904KH K16-1 Commercial 904 with Pb-Free bar-line indicator Pb-Free NiPdAu SY88904KHTR(1) K16-1 Commercial 904 with Pb-Free bar-line indicator Pb-Free NiPdAu Note: 1. Tape and Reel. 16-Pin MSOP (K16-1) PIN DEFINITIONS Pin Type VCC Power Supply GND Ground TX_Out TX_Fault PECL Output Open Collector Output Description Positive Power supply Ground Transmitter Enable Module Fault TX_Disable TTL Input Transmitter Disable and Fault Reset LOSIN TTL Input Loss-of-Signal Input from Limiting Post Amplifier VREF Analog Output Reference Voltage IPIN SET Analog Input Adjustable, Resistor to VREF sets Min. Monitor Diode Photo Current RWIN Analog Input Restart Window 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 ILIMIT SET Analog Input Adjustable, Resistor to VREF sets Laser Diode over current fail point. M9999-081005 [email protected] or (408) 955-1690 2 SY88904 Micrel, Inc. ABSOLUTE MAXIMUM RATINGS(1) Symbol Rating Value Unit VCC Power Supply Voltage 0 to +7.0 V TX_Disable, LOS Input Voltage 0 to VCC V –0.3V, VCC +0.3V V LOSOC, IPIN SET, ILIMIT IBIASFB, IBIAS SET SET Others; I/O Voltage TX_Out Output Voltage (with 50Ω load) VCC –2.5V, VCC +0.3V V TA Operating Temperature Range 0°C to +85°C °C Tstore Storage Temperature Range –55°C to +125°C °C 93 °C/W Theta Junction to Ambient 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. DC ELECTRICAL CHARACTERISTICS VCC = +5V, RLOAD = 50Ω to 3V, 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 Conditions No output load ICC Power Supply Current — — 60 — — 60 — — 60 mA IBIAS IBIAS Output Current 2 — 25 2 — 25 2 — 25 mA IBIAS SET IBIAS SET Input Current — — 0.625 — — 0.625 — — 0.625 mA M9999-081005 [email protected] or (408) 955-1690 3 SY88904 Micrel, Inc. DETAILED LOGIC DIAGRAM DESCRIPTION The SY88904 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 and modulation current control, laser diode driver enable and monitor diode interface. The device also interfaces with the SY88903 high-speed limiting amplifier providing chatter-free Loss of Signal function. The system functions provided include laser diode over-current detection, module fault signal and transmit disable control. The SY88904 also provides power up cycling of laser diode current and the fault detect signal. Power Up Sequence, TX_Disable asserted The SY88904 will power up in a TX_Fault condition and will remain in a fault condition while TX_Disable is asserted. Power Up Sequence, TX_Disable negated The SY88904 will power up in a TX_Fault condition and will remain in a fault condition until VCC is within operational limits, at which time an initialization sequence will be started. TX_Disable Cycle, TX_Fault Negated When the SY88904 is not in a TX_Fault condition, a rising edge of TX_Disable will cause the SY88904 to enter a TX_Fault condition. The falling edge of TX_Disable will cause a power up sequence to be started. Laser Diode Supply Current The SY88904 provides the adjustable drive current for the laser diode, DC bias. TX_Disable Cycle, TX_Fault Asserted When the SY88904 is in a TX_Fault condition, the falling edge of TX_Disable will cause an initialization sequence to be started. Laser Diode Over-Current Detection The SY88904 provides the ability to set an upper limit fail point for the laser diode. ILIMIT SET sets an upper limit for the average current present at the IBIAS pin. TX_Disable Cycle, during an initialization cycle A rising edge of TX_Disable will cause the SY88904 to terminate the current initialization cycle and remain in a TX_Fault condition. The falling edge of TX_Disable will cause the initialization sequence to be restarted. Monitor Diode The MD pin on the SY88904 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. The SY88904 will also generate a fault if the MD pin receives photo current less than IPINSET or is no longer connected to the monitor diode. Initialization Sequence The initialization sequence consists of a delay, set by the RC time constant on the Rwin input, followed by a power up sequence. Power Up Sequence A power up sequence will negate TX_Fault and then ramp up Ibias, controlled by the capacitor on the Rwin input and an internal 1mA current, followed by TX_OUT being negated and fault checking. If a fault occurs at this time the module will enter a TX_Fault conditions, otherwise the module will be ready for operation. Laser Diode Driver Enable The SY88904 provides a TX_Out pin used to control the output of the laser diode driver, through the Enable pin , of the SY88902. This is a single ended PECL output. Module Fault The SY88904 provides an open collector output, TX_Fault, that indicates to the host system that the module is in a fault condition. The SY88904 will assert TX_Fault when a low VCC condition is detected, when the monitor diode is not connected or when a laser diode over-current condition is detected. The SY88904 will attempt to clear a TX_Fault condition if the device is power cycled or a reset cycle is initiated with TX_Disable. When the SY88904 is in a TX_Fault condition Ibias will be removed, TX_Out will be negated and fault detection will be disabled. M9999-081005 [email protected] or (408) 955-1690 4 SY88904 Micrel, Inc. Fault Condition TX_FAULT IBIAS TX_Out TX_DISABLE RWIN Initialization Power up Figure 1. Reset of Temporary Fault Fault Condition TX_FAULT IBIAS TX_Out TX_DISABLE RWIN Initialization Power up Figure 2. Reset of Fatal Fault Fault Condition TX_FAULT IBIAS TX_Out TX_DISABLE RWIN Initialization 1 Initialization 2 Power up Figure 3. Reset During Initilization M9999-081005 [email protected] or (408) 955-1690 5 SY88904 Micrel, Inc. Fault Condition TX_FAULT IBIAS TX_Out TX_DISABLE RWIN Initialization 1 Initialization 2 Power up 1 Figure 4. Reset During Power Up Fault Condition TX_FAULT IBIAS TX_Out TX_DISABLE RWIN Power up Figure 5. Reset Cycle M9999-081005 [email protected] or (408) 955-1690 6 Power up 2 SY88904 Micrel, Inc. APPLICATION EXAMPLE FOR 3-CHIP SET SOLUTION GBIC Terminal TX_DATA+ TX_DATA– TX_FAULT TX_DISABLE VCC DIN DIN EN 0.1µF RSET MD VREF VCC OUT BLM21A102S Laser Module Photodiode 22nF 22nF VCC 1000pF VCC From Transimpedance Amplifier The value of RSER depends on the Laser Diode. RSER 20kΩ OUT VREF DIN DIN LOSLVL 0.1µF ILIMIT SET 20kΩ IPIN SET IBIAS FB IBIAS SET RWIN VCC 24Ω 20kΩ VREF GND SY88922 VCC IBIAS LOS VCC GND SY88904 VCCDET TX_OUT LOSOUT LOSIN EN REXT Laserdiode VREF 7 M9999-081005 [email protected] or (408) 955-1690 2MΩ 0.1µF 82Ω DOUT SY88993 GND 20kΩ 130Ω DOUT VCC 0.1µF RX_LOS RX_DATA+ RX_DATA– VCC 20kΩ 0.1µF 82Ω 50Ω 0.1µF 130Ω 50Ω SY88904 Micrel, Inc. 16 LEAD MSOP (K16-1) Rev. 01 MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 TEL + 1 (408) 944-0800 FAX + 1 (408) 474-1000 WEB USA 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 at Purchaser’s own risk and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale. © 2005 Micrel, Incorporated. M9999-081005 [email protected] or (408) 955-1690 8