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| Micrel, Inc. FIBER OPTIC MODULE CONTROLLER WITH APC SY88904 SY88904 FEATURES s DC bias current adjustable to 25mA s Buffered Loss-of-Signal output when used with SY88903 s Controlled laser diode turn on s Laser diode over-current detect s Monitor diode power control circuit s Laser diode driver enable s Designed for use with SY88902 and SY88903 s Single power supply s Available in 16-pin MSOP DESCRIPTION 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 s s s s s 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 LOSIN PECL PECL VREF 4 TX_Out II_LIMIT Fault Detect Circuit + ILIMIT SET VREF 3 TX_Fault OC MD_Low + TX_Disable TTL 40X IBIAS + VREF 2 VCC GND MD VCC DET VCC DET 4.75 RWIN IBIAS SET IBIAS FB IPIN SET VREF M9999-081005 hbwhelp@micrel.com or (408) 955-1690 Rev.: B Amendment: /0 1 Issue Date: August 2005 Micrel, Inc. SY88904 PACKAGE/ORDERING INFORMATION TX_Out VREF IBIAS ILIMIT SET IBIAS SET IBIAS FB MD IPIN SET 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 VCC LOSOUT Ordering Information Part Number Package Type K16-1 K16-1 K16-1 K16-1 Operating Range Commercial Commercial Commercial Commercial Package Marking 904 904 904 with Pb-Free bar-line indicator 904 with Pb-Free bar-line indicator Lead Finish Sn-Pb Sn-Pb Pb-Free NiPdAu Pb-Free NiPdAu LOSIN RWIN TX_Disable TX_Fault VCCDET GND SY88904KC SY88904KCTR(1) SY88904KH SY88904KHTR(1) Note: 1. Tape and Reel. MSOP K16-1 16-Pin MSOP (K16-1) PIN DEFINITIONS Pin VCC GND TX_Out TX_Fault TX_Disable LOSIN VREF IPIN SET RWIN LOSOUT IBIASFB IBIASSET MD IBIAS ILIMIT SET Type Power Supply Ground PECL Output Open Collector Output TTL Input TTL Input Analog Output Analog Input Analog Input PECL Output Analog Output Analog Input Analog Input Analog Input Analog Input Positive Power supply Ground Transmitter Enable Module Fault Transmitter Disable and Fault Reset Loss-of-Signal Input from Limiting Post Amplifier Reference Voltage Adjustable, Resistor to VREF sets Min. Monitor Diode Photo Current Restart Window Loss-of-Signal PECL output Monitor Diode Feedback Adjustable, Resistor to VREF sets the DC bias current for the Laser Diode Monitor Diode Connection DC bias current for the Laser Diode Adjustable, Resistor to VREF sets Laser Diode over current fail point. Description M9999-081005 hbwhelp@micrel.com or (408) 955-1690 2 Micrel, Inc. SY88904 ABSOLUTE MAXIMUM RATINGS(1) Symbol VCC TX_Disable, LOS LOSOC, IPIN SET, ILIMIT IBIASFB, IBIAS SET TX_Out TA Tstore SET Rating Power Supply Voltage Input Voltage Others; I/O Voltage Output Voltage (with 50 load) Operating Temperature Range Storage Temperature Range Theta Junction to Ambient Value 0 to +7.0 0 to VCC -0.3V, VCC +0.3V VCC -2.5V, VCC +0.3V 0C to +85C -55C to +125C 93 Unit V V V V C C C/W 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 = 50 to 3V, TA = 0C to +85C TA = 0C Symbol ICC IBIAS IBIAS SET Parameter Power Supply Current IBIAS Output Current IBIAS SET Input Current Min. -- 2 -- Typ. -- -- -- Max. 60 25 0.625 -- 2 -- TA = +25C Min. Typ. -- -- -- Max. 60 25 0.625 -- 2 -- TA = +85C Min. Typ. -- -- -- Max. 60 25 0.625 Unit mA mA mA Conditions No output load M9999-081005 hbwhelp@micrel.com or (408) 955-1690 3 Micrel, Inc. SY88904 DETAILED DESCRIPTION LOGIC DIAGRAM 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. Laser Diode Supply Current The SY88904 provides the adjustable drive current for the laser diode, DC bias. 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. 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. 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. 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. 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. 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. 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. M9999-081005 hbwhelp@micrel.com or (408) 955-1690 4 Micrel, Inc. SY88904 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 hbwhelp@micrel.com or (408) 955-1690 5 Micrel, Inc. SY88904 Fault Condition TX_FAULT IBIAS TX_Out TX_DISABLE RWIN Initialization 1 Initialization 2 Power up 1 Power up 2 Figure 4. Reset During Power Up Fault Condition TX_FAULT IBIAS TX_Out TX_DISABLE RWIN Power up Figure 5. Reset Cycle M9999-081005 hbwhelp@micrel.com or (408) 955-1690 6 SY88904 0.1F 20k 82 82 VREF RSET OUT TX_DATA+ DIN DIN 130 130 SY88922 EN VCC GND TX_DATA- OUT RSER BLM21A102S Laser Module REXT 24 APPLICATION EXAMPLE FOR 3-CHIP SET SOLUTION GBIC Terminal TX_OUT TX_FAULT TX_DISABLE IBIAS MD RWIN IBIAS SET 20k SY88904 LOSOUT VCCDET LOSIN 0.1F IPIN SET VREF 20k ILIMIT SET 20k VCC GND VREF 0.1F RX_LOS EN DOUT RX_DATA+ RX_DATA- LOS DIN 22nF DOUT 50 50 SY88993 DIN 0.1F 22nF From Transimpedance Amplifier LOSLVL VCC VCC VCC GND VREF 0.1F 20k M9999-081005 hbwhelp@micrel.com or (408) 955-1690 Micrel, Inc. 7 IBIAS FB The value of RSER depends on the Laser Diode. 0.1F 2M VCC 1000pF VCC Photodiode Laserdiode VCC VCC Micrel, Inc. SY88904 16 LEAD MSOP (K16-1) Rev. 01 MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 TEL USA + 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 at Purchaser's own risk and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale. (c) 2005 Micrel, Incorporated. M9999-081005 hbwhelp@micrel.com or (408) 955-1690 8 |
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