M02061 3.3 or 5 Volt Laser Driver The M02061 is a highly integrated, programmable laser driver intended for SFP/SFF modules. Using differential PECL data inputs, the M02061 supplies the bias and modulation current required to drive an edge-emitting laser. The modulation output can be DC-coupled to the laser diode. The M02061 includes automatic power control to maintain a constant average laser output power over temperature and life. In addition, the modulation current can be temperature compensated to minimize variation in extinction ratio over temperature. Applications Features * * * * * High speed operation; suitable for SFP/SFF applications. Typical rise/fall times of 55 ps. * Programmable temperature compensation. Modulation output and bias output can be controlled using a few discrete resistors. * Supports DDMI (SFF-8472) diagnostics * DC or AC coupled modulation drive. Up to 100 mA modulation current available when AC coupled. * Low overshoot allows high extinction ratio with low jitter * Automatic Laser Power Control, with "Slow-Start" * PECL and CML compatible differential data inputs * Complies with major MSAs (GBIC, SFF, SFF-8472, SFP) including timing requirements * Packaged in a QFN24 * 3.3V or 5V operation * Pulse width adjustment SFP and SFF Modules 1G/2G/4G Fibre Channel modules Short reach and Metro SONET/SDH CPRI: 614.4, 1228.8, 2457.6, 3072.0, 4915.2 and 6144.0 Mbit/s Internal 3.3V reg. VCC PWA VCC3 VCC3 VCC VCC SHDWNOUT Typical Applications Diagram VCC Internal Power Bus SVCC OUT- DIN + Input Buffer DIN- Laser Driver Output Buffer D - FF OUT+ GND0 VCC3 -1.3V IBIASOUT IPIN Input Buffer V CC (M02061-21 only) 02061-DSH-001-F CAPC DISDLY TxPwrMON BIASMON APCSET MODMON Automatic Power Control (laser bias current) MODSET TCSLOPE VCC3SEL Modulation Control SCB FAIL DIS RESET Safety Circuitry with Latched Fault TX Disable VCC3 (M02061-12 only) Mindspeed Technologies(R) Mindspeed Proprietary and Confidential February 2010 Ordering Information Part Number Package Pin Confitguration M02061-12 QFN24 DISDLY function on pin 8 M02061G-12* QFN24 (RoHS Compliant) DISDLY function on pin 8 M02061-21 QFN24 SCB function on pin 8 M02061G-21* QFN24 (RoHS Compliant) SCB function on pin 8 M02061-EVM Combination Optical and Electrical Evaluation board DISDLY function on pin 8 *The G in the part number indicates that this is an RoHS compliant package. Refer to www.mindspeed.com for additional information. Revision History Revision Level Date ASIC Revision F Release February 2010 x Added CPRI data rates to front page. Added TJ specification and added equation for TA specification in Table 1-1. E Release February 2006 x Added information for the M02061-21 with pin SCB instead of pin DISDLY. D Release September 2005 x New format. Remove 32 pin package information. Description Changes to Absolute Maximum Specifications - operating temperature, output voltage. Changes to Recommended Operating Conditions - VCC, operating temperature. Changes to DC Characteristics - ICC, VMD, TxPWRmon, logic inputs and outputs, data inputs, safety logic thresholds. Changes to AC Characteristics - IMOD, Tr, Tf, jitter. Added eye diagram, ; corrected rise/fall times. 19 24 VCC SHDWN OUT QFN24 Pin Configuration TCSLOPE 2.5Gbps Electrical Eye Diagram CAPC x VCC3 March 2004 PWA Preliminary MOD SET C 1 18 SVCC DIN+ OUT- DIN- OUT+ VCC3SEL GND 0 GND, connect to PCB ground DIS FAIL IBIASOUT 6 13 7 IPIN 12 02061-DSH-001-F Mindspeed Technologies(R) Mindspeed Proprietary and Confidential APC SET TXPWRMON BIASMON MODMON SCB/DISDLY RESET Conditions: 80mA modulation current, 2^7-1 PRBS 4mm x 4mm 2 1.0 Product Specification 1.1 Absolute Maximum Ratings Table 1-1. Absolute Maximum Ratings Symbol Parameter Rating Units VCC Power supply voltage -0.4 to +6.0 V TJ Junction temperature -40 to +110 1 C -0.4 to +4.0 V Operating ambient temperature -40 to +95 2 C Storage temperature -65 to +150 C VCC3 TA TSTG 3.3V power supply voltage IBIASOUT (MAX) Maximum bias output current 150 mA IMOD (MAX) Maximum modulation current 140 mA 0 to VCC3 + 0.4 V DIN+/- Data inputs DIS, SCB, VCC3SEL Mode control inputs -0.4 to VCC + 0.4 V BIASMON, MODMON Bias and modulation output current mirror compliance voltage -0.4 to VCC3 + 0.4 V IPIN Photodiode anode voltage -0.4 to VCC3 + 0.4 V IPIN Photo diode current 2 mA FAIL Status flags -0.4 to VCC + 0.4 V Set inputs -0.4 to VCC3 + 0.4 V -0.4 to 1.0 V PWA, APCSET, MODSET TCSTART Temperature compensation start temperature TCSLOPE Temperature compensation slope -0.4 to VCC3 + 0.4 V Output -0.4 to VCC + 0.4 V OUT+, OUT1. QFN package: Air Velocity JA 0 m/s 57 C/W 1 m/s 50 C/W 2.5 m/s 45 C/W The above thermal resistance is based on a 4-layer JEDEC standard board (76.2 x 114.3 mm). 2. The maximum operating ambient temperature is the lesser of 95 C or TA TJ(Max) - (JA (Max) x Q) where Q is the power dissipated in the M02061. These are the absolute maximum ratings at or beyond which the IC can be expected to fail or be damaged. Reliable operation at these extremes for any length of time is not implied. 02061-DSH-001-F Mindspeed Technologies(R) Mindspeed Proprietary and Confidential 3 Product Specification 1.2 Recommended Operating Conditions Table 1-2. Recommended Operating Conditions Parameter Power supply (VCC-GND) Rating Units 3.3 7.5% V or 5.0 + 8%, -5% Operating ambient -40 to + 95 1.3 C DC Characteristics (VCC = +3.05V to +3.55V or 4.75V to 5.4V, TA = -40 C to +95 C, unless otherwise noted) Typical values are at VCC = 3.3 V, IBIASOUT = 30 mA, IMOD = 30 mA, TA = 25 C, unless otherwise noted. Table 1-3. DC Characteristics (1 of 3) Symbol ICC IBIAS Parameter Supply current excluding IMOD and IBIAS Bias current adjust range Conditions Minimum Typical Maximum Units PWA high (no pulse width adjust) - 35 61 mA additional current when PWA used - 1.5 - additional current when operating from a 5V supply - 1.5 - V(IBIASOUT) > 0.7V For 3.3V operation with an AC coupled laser mA 1 100 1 60 For 5.0V operation with a DC coupled laser. IBIAS(OFF) Bias current with optical output disabled DIS = high - - 300 A - 100 - A/A V(IBIASOUT) > VCC - 1V Ratio of IBIAS current to BIASMON current VMD Monitor diode reverse bias voltage VCC =3.3V 1.5 - - V IMD Monitor diode current adjustment range Adjusted with RAPCSET 10 - 1500 A 0.95 1 1.25 A/A 100 pF 5.4 V Ratio of TxPwrMON current to monitor photodiode current CMD_MAX Maximum monitor photodiode capacitance for APC loop stability. Includes all associated parasitic capacitances. TTL/CMOS input high voltage (DIS) 02061-DSH-001-F 2.0 Mindspeed Technologies(R) Mindspeed Proprietary and Confidential - 4 Product Specification Table 1-3. DC Characteristics (2 of 3) Symbol Parameter Conditions TTL/CMOS input low voltage (DIS) Minimum Typical Maximum Units - - 0.8 V CMOS input high voltage (VCC3SEL, SCB) 2.4 V CMOS input low voltage (VCC3SEL, SCB) 1.2 V Logic output high voltage (FAIL) With external 10k pull-up to VCC. VCC - 0.5 - - V Logic output low voltage (FAIL) For 6.8k to 10k resistor when pulled up to 5V. - - 0.4 V Differential input impedance Data inputs - 6800 - VSELF Self-biased common-mode input voltage - VCC3 - 1.3 - V VINCM Common-mode input compliance voltage Data inputs VCC3 - 1.45 - VCC3-[VIN(Diff)]/4 V Differential input voltage = 2 x (DIN+HIGH - DIN+LOW) 200 - 2400 mVpp 2.5 2.8 3.0 V 3.65 3.9 4.25 V For 4.7k to 10k resistor when pulled up to 3.3V. RIN VIN(DIFF) (1) VCC3THL 3.3V supply detection, lower threshold VCC3THH(1) 3.3V supply detection, upper threshold VCC5THL 5V supply detection, lower threshold 3.9 4.25 4.65 V VCC5THH 5V supply detection, upper threshold 5.4 5.8 6.1 V VREF1 Reference voltage for MODSET 1.18 1.3 1.4 V VAPCSET Reference voltage for APCSET VBL Bias_OK lower voltage threshold 02061-DSH-001-F 1.3 0.88 Mindspeed Technologies(R) Mindspeed Proprietary and Confidential 1.0 V 1.05 V 5 Product Specification Table 1-3. DC Characteristics (3 of 3) Symbol VBH Parameter Conditions Bias_OK upper voltage threshold VFAULTL Lower voltage threshold for fault inputs IBIASOUT, OUT+, CAPC, AND MODSET FAIL asserts if any of these signals fall below this value. VOUT_DIS Self bias voltage for IBIASOUT and OUT+ DIS = high VSHDWNL SHDWNOUT output low voltage DIS = low, ISHDWNOUT 100uA VSHDWNH SHDWNOUT output high voltage DIS = low, ISHDWNOUT 10uA Minimum Typical Maximum Units 1.45 1.6 1.7 V 300 400 mV 1.65 2.2 V VCC - 4 V 0.5 VCC - 0.3V V NOTES: 1. When VCC = 5V, VCC3 "supply OK" circuitry monitors the internally regulated 3.3V supply. When VCC = 3.3V, VCC3 "supply OK" circuitry monitors VCC. 1.4 AC Characteristics (VCC = 3.05 V to 3.55V or 4.75V to 5.4V, TA = -40 C to +95 C, unless otherwise noted) Typical values are at VCC = 3.3 V, IBIASOUT = 30 mA, IMOD = 30 mA, 25 ohm load and TA = 25 C, unless otherwise noted. Table 1-4. AC Characteristics (1 of 2) Symbol IMOD IMOD(OFF) Parameter Conditions Modulation current range 3.3V operation, AC coupled, OUT+ and OUT>1.6V Modulation current with output disabled Programmable range for modulation current temperature coefficient 02061-DSH-001-F 10 - 100 Units mA 5V operation, DC coupled(1) into a 25 load to VCC - 1.2V. OUT+ and OUT- >1.15V 10 DIS = high - - 300 A - 100 - A/A 0 - 104 ppm/C Ratio of modulation current to MODMON current IMOD-TC Minimum Typical Maximum Adjustable using TCSLOPE (2) Mindspeed Technologies(R) Mindspeed Proprietary and Confidential 80 6 Product Specification Table 1-4. AC Characteristics (2 of 2) Symbol Parameter tr Modulation output rise time tf Modulation output fall time OS Overshoot of modulation output current in the off direction. RJ Random jitter DJ Conditions Minimum Typical Maximum 20% to 80% into 25 . Measured using 11110000 pattern at 2.5Gbps (2) into 25 load Deterministic jitter Measured into 25 load, Gbps 231 Units - 55 75 ps - 55 75 ps -- 1 - % - 0.8 - psrms 10 25 10 30 - 1 PRBS at 2.7 pspp K28.5 pattern at 4.25 Gbps (includes pulse width distortion3) NOTES: 1. Guaranteed by design and characterization. 2. DC coupled operation at 3.3V is not supported. AC coupled operation at 5V is possible provided the outputs never exceed 6V. 3. Pulse width distortion is measured single-ended. 1.5 Safety Logic Timing (SCB pin low, VCC = 3.05 V to 3.55V or 4.7V to 5.4V, TA = -40 C to +95 C, unless otherwise noted) Table 1-5. Safety Logic Timing (1 of 2) Symbol Parameter Conditions Minimum Typical Maximum Units t_off DIS assert time Rising edge of DIS to fall of output signal below 10% of nominal(1) 10 s t_on DIS negate time Falling edge of DIS to rise of output signal above 90% of nominal(1) 1 ms t_init Time to initialize(2) Includes reset of FAIL; from power on after Supply_OK or from negation of DIS during reset of FAIL condition 5 ms 02061-DSH-001-F Mindspeed Technologies(R) Mindspeed Proprietary and Confidential 2 3 7 Product Specification Table 1-5. Safety Logic Timing (2 of 2) Symbol Parameter Conditions Minimum Typical Maximum Units t_fault Laser fault time - from fault condition From occurrence of fault condition or when to assertion of FAIL Supply_OK is beyond specified range 100 s t_reset DIS time to start reset DIS pulse width required to initialize safety circuitry or reset a latched fault 10(3) s tVCC_OK Supply_OK delay time Delay between Supply_OK condition and when outputs are enabled t_onBM DIS negate (turn-on) time during burst-mode operation IMOD > 20mA; outputs DC coupled (5V operation)(4) 300 500 ns t_offBM DIS assert (turn-off) time during burst-mode operation IMOD > 20mA; outputs DC coupled (5V operation) 200 500 ns 10 s 20 NOTES: 1. With CAPC < 2.2nF 2. User-adjustable. Specifications reflect timing with no external RESET capacitor. 3. With < 1nF capacitor from RESET pin to ground. 4. Imod >12mA Figure 1-1. Relationship between Data Inputs and Modulation Outputs DIN+ 100 mV 1200 mV D IN- 200 mV 2400 mV V IN(DIFF) V OUT- V OUT+ > 1.60V when VCC5_OR high > 1.15V when VCC5_OR low GND 02061-DSH-001-F Mindspeed Technologies(R) Mindspeed Proprietary and Confidential 8 Product Specification Figure 1-2. Safety Logic Timing Characteristics, SCB pin low Slow Rise on Vcc = 5V at Power-up (DIS Low) Hot Plug (DIS Low) 5V VCC3 and VCC5 status FAIL DIS VCC3 and VCC5 "OK" VCC 3.3V VCC3 (low) FAIL (low) DIS (low) (low) t_on < 1ms, (300 s typ.) t_on < 1ms, (300 s typ.) LASER OUTPUT LASER OUTPUT Slow Rise on Vcc=3.3V at Power-up (DIS Low) Transmitter Enable (DIS transition Low) 3.3V VCC 3.3V VCC3 and VCC5 status (high) FAIL (low) DIS (low) VCC3 and VCC5 "OK" VCC3 FAIL state at power-up will depend on pull-up voltage FAIL DIS (low) (low) t_on < 1ms, (300 s typ.) LASER OUTPUT 02061-DSH-001-F t_on < 1ms, (300 s typ.) LASER OUTPUT Mindspeed Technologies(R) Mindspeed Proprietary and Confidential 9 Product Specification Transmitter Disable (DIS transition high) (high) VCC3 and VCC5 status VCC3 and VCC5 "OK" Fault recovery at: MODSET. CAPC, OUT+, or IBout DIS DIS t_off < 10 s, (1 s typ.) LASER OUTPUT Response to Fault Fault at: MODSET. CAPC, OUTP, or IBout FAIL DIS LASER OUTPUT 02061-DSH-001-F Fault Removed FAIL remains high until reset by DIS going high FAIL (low) FAIL Fault Recovery Behavior t_reset, 10 s, min. t_on < 1ms LASER OUTPUT Unsuccessful Fault Reset Attempt Fault Occurs Fault Remains Fault at: APCSET t_fault < 100 s, (4 s typ.) t_init < 5ms, (3ms typ.) FAIL DIS t_reset, 10 s, min. LASER OUTPUT Mindspeed Technologies(R) Mindspeed Proprietary and Confidential 10 2.0 Pin Definitions Table 2-1 lists pin type definitions and descriptions for the M02061 device. Table 2-1. M02061 Pin Definitions and Descriptions (1 of 7) 4x4 mm QFN24 Pin Number Pin Name 1 VCC 2 DIN+ Pin equivalent load Function Power supply V CC3 V CC Positive data input. Self biased. Compatible with AC coupled PECL, AC coupled CML, and DC-coupled PECL (VCC = 3.3V). When DIN+ is high, OUT+ sinks current. V TT 4 k D IN+, DIN-, or CLK+, CLK- 3 DIN- 4 VCC3SEL See DIN+ drawing VCC Negative data input. Self biased Compatible with AC coupled PECL, AC coupled CML, and DC-coupled PECL (VCC = 3.3V). VCC3 3.3V VCC Select. Connect to VCC3 for VCC = 3.3V operation. Connect to GND for VCC = 5V operation. VCC5_ OR 190 72 k 02061-DSH-001-F Mindspeed Technologies(R) Mindspeed Proprietary and Confidential 11 Pin Definitions Table 2-1. M02061 Pin Definitions and Descriptions (2 of 7) 4x4 mm QFN24 Pin Number Pin Name 5 DIS Pin equivalent load Function Bias and modulation output disable (TTL/CMOS). V CC V CC3 7 k DIS 80 k 6 FAIL Safety circuit control failure output (TTL/CMOS). Goes high when a safety logic fault is detected. This output will be low when DIS is high. VCC FAIL 7 RESET VCC3 V CC Safety circuit reset. Leave open for normal operation or add a capacitor to ground to extend the reset time. Connect to GND to disable window comparators at APCSET RESET 190 02061-DSH-001-F Mindspeed Technologies(R) Mindspeed Proprietary and Confidential 12 Pin Definitions Table 2-1. M02061 Pin Definitions and Descriptions (3 of 7) 4x4 mm QFN24 Pin Number Pin Name 8 SCB (M02061-21 only) Pin equivalent load VCC V CC3 Function Safety Circuit Bypass. Connect to GND or leave open for normal operation. Connect to VCC to allow the bias and modulation outputs to operate even if the safety circuitry indicates a fault. SCB 24 k 48 k 8 DISDLY Disable delay control. Connect to ground for normal operation. In burst mode operation add a capacitor from this pin to ground to set the maximum disable time. Disable times greater than this maximum will engage the "slow-start" circuitry. V CC (M02061-12 only) DISDLY 190 9 MODMON V CC VCC3 Modulation Current Monitor. Connect directly through a resistor to GND (MONPOL high) or to VCC3 (MONPOL low). The current through this pin is approximately 1/100th of the MODULATION current to the laser This pin may be left open if the feature is not needed and the M02061 current consumption will be reduced by 0.5mA typically. MOD MON 190 02061-DSH-001-F Mindspeed Technologies(R) Mindspeed Proprietary and Confidential 13 Pin Definitions Table 2-1. M02061 Pin Definitions and Descriptions (4 of 7) 4x4 mm QFN24 Pin Number Pin Name Pin equivalent load Function 10 BIASMON See MODMON drawing Bias Current Monitor. Connect directly through a resistor to GND (MONPOL high) or to VCC3 (MONPOL low). The current through this pin is approximately 1/100th of the BIAS current to the laser. This pin may be left open if the feature is not needed and the M02061 current consumption will be reduced by 0.5mA typically. 11 TxPwrMON VCC VCC3 Transmit Power Monitor. Connect directly through a resistor to GND (MONPOL high) or to VCC3 (MONPOL low). The current through this pin is approximately the same as the photo diode current into IPIN. This pin may be left open if the feature is not needed and the M02061 current consumption will be reduced by the IPIN current. TxPwr MON 33 12 APCSET V CC VCC3 Average Power Control, laser bias current adjustment. Connect a resistor between this pin and ground to set the bias current to the laser. The APC loop will control the laser bias current to maintain a voltage of approximately 1.3V at this pin. The current through this pin is approximately the same as the current into IPIN. APCSET 13 IPIN Current input from monitor photodiode anode. VCC The APC loop will adjust the laser bias current to maintain a voltage at APCSET of approximately 1.3V and at this pin of approximately one VGS. The voltage at this pin will not exceed 1.6V in normal operation IPIN 30 02061-DSH-001-F Mindspeed Technologies(R) Mindspeed Proprietary and Confidential 14 Pin Definitions Table 2-1. M02061 Pin Definitions and Descriptions (5 of 7) 4x4 mm QFN24 Pin Number Pin Name 14 IBIASOUT Pin equivalent load Function Laser bias current output. VCC Connect directly to laser cathode or at higher bit rates through a ferrite or a resistor to isolate the capacitance of this pin from the modulation drive, (~2pF). Maintain a voltage > 0.7V at this pin. IBIASOUT 15 GNDO V Ground for output stage. May be connected directly to ground. At high bit rates (>2Gb/s) an optional inductor or ferrite may be added to reduce switching transients. CC GND0 16 OUT+ Positive modulation current output. Sinks current when DIN+ is HIGH. VCC Maintain a voltage > 1.6V at this pin when VCC3SEL is high. Maintain a voltage > 1.15V at this pin when VCC3SEL is low. OUT+ GND 0 17 OUT- See OUT+ drawing Negative modulation current output. Sinks current when DIN- is HIGH Maintain a voltage > 1.6V at this pin when VCC3SEL is high. Maintain a voltage > 1.15V at this pin when VCC3SEL is low. 02061-DSH-001-F Mindspeed Technologies(R) Mindspeed Proprietary and Confidential 15 Pin Definitions Table 2-1. M02061 Pin Definitions and Descriptions (6 of 7) 4x4 mm QFN24 Pin Number Pin Name 18 SVCC Pin equivalent load Function Switched VCC. VCC V CC3 3.3V applications - Connect to laser anode. Safety circuitry will open the switch when a fault is detected and no current will flow through the laser. No capacitance is needed on this node. If capacitance to ground is added, do not exceed 100pF. SV CC 19 SHDWNOUT 5V applications - Disabled, leave open. 12 k SHDWNOUT 20 CAPC External switched VCC control signal. Use in 5V applications to create an external SVCC. V CC Automatic power control loop dominant pole capacitor. (Connect a capacitor between this pin and VCC3.) VCC A 2.2nF capacitor will give less than 1ms enable time and a loop bandwidth < 30kHz C APC 100 02061-DSH-001-F Mindspeed Technologies(R) Mindspeed Proprietary and Confidential 16 Pin Definitions Table 2-1. M02061 Pin Definitions and Descriptions (7 of 7) 4x4 mm QFN24 Pin Number Pin Name 21 VCC3 Pin equivalent load Function 3.3V applications - Power supply input. Connect to VCC. V CC V CC 5V applications - Internally generated 3.3V. Power supply output. Do not attach to non-M02061 circuitry. For 5V applications add 12 ohms in series with 100nF to ground at this pin. V CC3 22 PWA V CC Pulse Width Adjust. Connect a resistor to GND to enable, (between 1k and 20k). Connect to VCC3 to disable. V CC3 + - PWA 1.28V 190 23 MODSET See PWA drawing Modulation current control. Connect a resistor to ground to set the modulation current. 24 TCSLOPE See PWA drawing Modulation current temperature compensation coefficient adjustment. Connect a resistor to ground to set the temperature compensation coefficient. Leave open to disable the temperature compensation. A 51k resistor will result in a temperature compensation slope of approximately 0.5%/C CENTER GND Connect to GND. PAD 02061-DSH-001-F Mindspeed Technologies(R) Mindspeed Proprietary and Confidential 17 Pin Definitions 19 24 VCC SHDWNOUT CAPC VCC3 PWA MODSET QFN24 Pinout Information TCSLOPE Figure 2-1. 1 18 SVCC DIN+ OUT- DIN- OUT+ VCC3SEL GND 0 GND, connect to PCB ground DIS 6 13 02061-DSH-001-F IPIN TXPWRMON BIASMON MODMON 12 SCB/DISDLY RESET 7 Mindspeed Technologies(R) Mindspeed Proprietary and Confidential APCSET FAIL IBIASOUT 4mm x 4mm 18 3.0 Functional Description 3.1 Overview The M02061 is a highly integrated, programmable laser driver intended for SFP/SFF module with data rates up to 4.25 Gbps. Using differential PECL data inputs, the M02061 supplies the bias and modulation current required to drive an edge-emitting laser. Monitor outputs and internal safety logic in the M02061 combined with the M02088 will support designs requiring DDMI compliance. The M02061 includes automatic power control to maintain a constant average laser output power over temperature and life. In addition, the modulation current can be temperature compensated to minimize variation in extinction ratio over temperature. Many features are user-adjustable, including the APC (automatic power control) loop bias control (via a monitor photo diode), modulation current, temperature compensation control of modulation current, and pulse-width adjustment. The part may be operated from a 3.3V or 5V supply. The driver modulation output can be AC, DC, or Differentially coupled to the laser. Safety circuitry is also included to provide a latched shut-down of laser bias and modulation current if a fault condition occurs. An internal VCC switch provides redundant shutdown when operating the device from a 3.3V supply. Control is provided to allow for a redundant external switch when operating with a 5V supply, if desired. Figure 3-1 details the functional blocks and pin signals for the M02061 device. 02061-DSH-001-F Mindspeed Technologies(R) Mindspeed Proprietary and Confidential 19 Functional Description Internal 3.3V reg. SHDWNOUT PWA VCC3 M02061 Block Diagram VCC Figure 3-1. Internal Power Bus SV CC OUT- DIN + Input Buffer DIN - D - FF Output Buffer Laser Driver OUT+ GND0 VCC3 -1.3V IBIAS OUT IPIN Mindspeed Technologies(R) Mindspeed Proprietary and Confidential CAPC DISDLY (M02061-12 only) TxPwrMON BIASMON APCSET Automatic Power Control (laser bias current) MODMON MODSET TCSLOPE Modulation Control VCC3SEL SCB (M02061-21 only) FAIL DIS 02061-DSH-001-F RESET Safety Circuitry with Latched Fault TX Disable 20 Functional Description Figure 3-2. 2.5Gbps Electrical Eye Diagram Conditions: 80mA modulation current, 27-1 PRBS 02061-DSH-001-F Mindspeed Technologies(R) Mindspeed Proprietary and Confidential 21 Functional Description Figure 3-3. 2.5Gbps Filtered Optical Eye Diagram with NEC NX7315UA Laser Conditions: 10dB extinction ratio, 33% eye margin, 27-1 PRBS Figure 3-4. 4.25Gbps Unfiltered Optical Eye Diagram with Archcom AC3460 Laser Conditions: 7.5dB extinction ratio, 27-1 PRBS 02061-DSH-001-F Mindspeed Technologies(R) Mindspeed Proprietary and Confidential 22 Functional Description 3.2 Features * High speed operation; suitable for SFP/SFF applications from 155Mbps to 4.25 Gbps. Typical rise/fall times of 55 ps. * Programmable temperature compensation. Modulation output and bias output can be controlled using a few discrete resistors. * Supports DDMI (SFF-8472) diagnostics when combined with the M02088. * DC or AC coupled modulation drive. Up to 100mA modulation current available when AC coupled. * Low overshoot allows high extinction ratio with low jitter. * Automatic Laser Power Control, with "Slow-Start". * Differential data inputs to minimize pattern dependent jitter, PECL and CML compatible. * Packaged in a QFN24 * 3.3V or 5V operation 3.3 General Description The M02061 is a highly integrated, programmable laser driver intended for SFP/SFF module with data rates up to 4.25 Gbps. Using differential PECL data inputs, the M02061 supplies the bias and modulation current required to drive an edge-emitting laser. Monitor outputs and internal safety logic support the DDMI requirements. The M02061 laser driver consists of the following circuitry: an internal regulator, bias current generator and automatic power control, data inputs, buffer with pulse width adjust, modulation current control, modulator output, laser fail indication, disable control, and monitor outputs for the bias current, modulation current, and transmitted power. 3.3.1 Internal Regulator The M02061 contains an internal 3.3V regulator so high bit rate performance can be achieved with 5V or 3.3V power supply. When operating from a 5V supply (VCC is connected to +5V), an internal regulator provides a voltage of approximately 3.3V to the majority of the on-chip circuitry. The on-chip regulator is internally compensated, requiring no external components. However, for 5V operation with high modulation currents, it may be necessary to add 12 ohms in series with 100nF to ground at VCC3 or the internal power supply may dip and cause a fault condition. When a 3.3V supply is used (VCC and VCC3 connected to 3.3V) the regulator is switched off and the internal circuitry is powered directly through the VCC3 supply pin. The decision as to whether or not the internal regulator is required is made via the VCC3SEL pin, which also determines whether the safety circuitry needs to monitor for proper +5V supply voltage. For 3.3V applications, SVCC is sourced from VCC3 through a switch (leave SVCC open for 5V applications). SVCC is to be used to power the anode of the laser diode and the cathode of the photo diode, any resistive or ferrite pullups on the OUT+ and OUT- outputs should be connected directly to VCC. When a fault condition is present, FAIL will assert and the switch sourcing SVCC will open so no current can pass through the laser. SVCC does not need any external capacitance, if capacitance to ground is added at SVCC it should be <100pF. For 5V operation, an analog switch controlled by SHTDWNOUT can be used to source 5V to the laser anode. In the case of a fault condition, SHTDWNOUT will go high and open the analog switch which will result in an open circuit at the laser. SHTDWNOUT is designed to drive a CMOS logic input. An FET transistor may have excessive Miller capacitance and a fault may be signalled if it turns on too slow. 02061-DSH-001-F Mindspeed Technologies(R) Mindspeed Proprietary and Confidential 23 Functional Description VCC and VCC3 status are internally monitored by the M02061 during power-up and normal operation. During power-up the "slow-start" circuitry requires that VCC and VCC3 each reach an acceptable level before enabling bias or modulation current. Table 3-1. Pin Connection for 3.3V and 5V VCC Pin Connection For: Pins Dependent on VCC Voltage VCC = 3.3V 3.3.2 VCC = 5V VCC3 Connect to VCC Reference for CAPC and PWA SVCC Laser Anode OPEN OPEN External safety control switch SHDWNOUT CAPC Capacitor between CAPC and VCC3 or VCC Capacitor between CAPC and VCC3 (not VCC) PWA Connect to VCC3 or VCC to disable Connect to VCC3 to disable (not VCC) Connect to VCC3 or VCC Connect to GND VCC3SEL Bias Current Generator and Automatic Power Control To maintain constant average optical power, the M02061 incorporates a control loop to compensate for the changes in laser threshold current over temperature and lifetime. The bias current will be determined by the value of the external resistor RAPCSET and the transfer efficiency between the laser and monitor photo diode. The photo current from the monitor photo diode mounted in the laser package is sunk at IPIN. This photo current is mirrored and an equivalent current is sourced from pins TxPwrMON and APCSET. The APC loop adjusts the laser bias current (hence the monitor diode photo current) to maintain a voltage at APCSET of 1 band-gap voltage or ~1.3V. RAPCSET * IPIN = 1.3 V The APC loop has a time constant determined by CAPC, RAPCSET and the transfer efficiency between the laser and monitor photo diode. The larger the CAPC capacitor the lower the bandwidth of the loop and the larger RAPCSET the lower the loop BW. In general, it is recommended that at least 2.2 nF of external capacitance be added externally between CAPC and VCC3. With use of a 2.2 nF capacitor, the bias current can reach 90% of its final value within 1ms, i.e., bias current rise-time is less than 1ms and the APC loop bandwidth is less than 30 kHz, which should be adequate for bit rates of 155Mbps. (and all higher bit rates). The bias generator also includes a bias current monitor mirror (BIASMON), whose output current is typically 1/100th of the bias current. This pin can be connected directly through a resistor to ground. If this function is not needed this pin can be left open. 3.3.3 Data Inputs Both CML and PECL inputs signals can be AC coupled to the M02061. These inputs are internally biased to approximately VCC3 - 1.3V. In most applications the data inputs are AC coupled with controlled impedance pcb traces which will need to be terminated externally with a 100 or 150 resistor between the + and - inputs. PECL and CML signals may be DC coupled to the M02061 data inputs when both the M02061 and the source of the input signals are operating from 3.3V supplies. If the M02061 is operating from a 5V supply, PECL and CML 02061-DSH-001-F Mindspeed Technologies(R) Mindspeed Proprietary and Confidential 24 Functional Description signals may be DC coupled as long as the source of the input signals is operating at a 3.3V supply and the signals are referenced to VCC3 at the M02061. 3.3.4 Pulse Width Adjust The data output buffer incorporates pulse-width adjustment control to compensate for laser pulse width distortion. A potentiometer can be connected between the PWA input and GND for adjustment (programming resistance should be between 1k and 20k). By adjusting the potentiometer, the pulse-width can be adjusted over a range of approximately 40 ps. Pulse width control can be disabled by connecting PWA to VCC3, resulting in roughly a 50% crossing point at the output and reducing supply current by approximately 1.5mA. 3.3.5 Modulation Control There are programmable control lines for controlling the modulation current and its temperature compensation. These inputs can be programmed simply with a resistor to ground. The modulation current amplitude is controlled by the MODSET input pin. The modulation current is temperature compensated by the TCSLOPE inputs. The temperature compensation is independent of the setting. If the temperature compensation at TCSLOPE is disabled, the modulation output current is simply: IOUT = 100 x (1.3V / RMODSET) Where RMODSET is the resistance from pin MODSET to ground. Figure 3-5 is the most accurate method for selecting RTCslope. However, you can also select RTCSLOPE using the following relationship: RTCSLOPE = 19.5*(TC)-1.5, where TC is the desired slope of the modulation current from 25C to 85C in%/C and RTCSLOPE is in k. If no temperature compensation is desired, leave RTCSLOPE open. In any case, RTCSLOPE will have negligible effect at M02061 case temperatures below 10C. For example: Given a laser with a desired modulation current at low temperatures of 30mA and a temperature coefficient of 0.5%/C at high temperatures (which will require a laser driver temperature coefficient of +0.5%). Choose RMODSET = 100 x (1.3V / 30mA) = 4.3k Choose RTCSLOPE =19.5*(0.5)-1.5 k = 56k. 02061-DSH-001-F Mindspeed Technologies(R) Mindspeed Proprietary and Confidential 25 02061-DSH-001-F Mindspeed Technologies(R) Mindspeed Proprietary and Confidential -30.00 -20.00 -10.00 0.00 -40 10.00 20.00 30.00 40.00 50.00 60.00 -20 0 40 Ambient Temperature in degrees C 20 60 80 100 750k open 390k 220k 150k 120k 100k 75k 82k 62k 51k 47k 39k 33k 27k 22k RTCslope: Functional Description Figure 3-5. 26 % change in modulation current Functional Description 3.3.6 Modulator Output The output stage is designed to drive a 25 output load over a wide range of currents and circuit architectures. The laser may be AC, DC, or Differentially coupled depending on the supply voltage. Table 3-2. Modulation Current Maximums VCC=5V, Laser DC coupled Max Modulation Current Max Bias Current 80 60 (1) VCC=5V, Laser AC coupled 80 (2) VCC=3.3V, Laser DC coupled 100 VCC=3.3V, Laser AC coupled 100 60 100 100 When differentially coupling, the maximum modulation and bias current is determined by either the AC or DC coupling of the OUT+ or OUT- output, whichever has the minimum rating. 1. When AC coupling the output should never be allowed to swing above the absolute voltage rating of the part, which is 6V. 2. When VCC=3.3V, the OUT+ and OUT- should not be driven below 1.6V. In most 3.3V applications, this will make DC coupling impractical. When DC coupled, OUT+ should be connected through a series resistor to the laser such that the total impedance seen at the output is 25 ohms. This will result in the optimum pulse response while allowing the maximum modulation current (see Figure 4-2). The output can also be AC coupled to the laser. This is the required operating mode when using a 3.3V supply (unless the laser has a small forward voltage and OUT+ will not go below 1.6V). When AC coupled the dynamic resistance seen by OUT+ should still be 25 ohms. In addition to a resistor in series with the laser, a capacitor is added in series and a ferrite is used to pull up the collector at OUT+ to VCC. When the laser is AC coupled, the OUT- pin is usually tied to the laser anode through an AC coupled series resistor which matches the impedance seen by the OUT+ pad (see Figure 4-1). The output stage also has a separate current path to GND labelled GND0. This isolates the output switching currents from the rest of the system. 02061-DSH-001-F Mindspeed Technologies(R) Mindspeed Proprietary and Confidential 27 Functional Description Figure 3-6. Modulator Output 0.4pF 0.75 nH * 0.75 nH * OUT- OUT+ For VCC =5V, OUT+ and OUTshould not be driven below 1.15V For VCC = 3.3V, OUT+ and OUTshould not be driven below 1.6V. GND A (optional external inductance) 3.3.7 * Denotes bond wire internal to MLF package Fail Output The M02061 has a FAIL alarm output which is compatible with the TX_FAULT signalling requirements of common pluggable module standards. The ESD protection on this pin provides a true open collector output that can withstand significant variation in VCC when signalling between circuit boards. Also, if the M02061 loses power the pull-up will signal a fail condition. In a simple static protection scheme used by other ICs the protection diodes would clamp the FAIL signal to ground when the chip loses power. 3.3.8 TX Disable and Disable Delay Control The DIS pin is used to disable the transmit signal (both the modulation and bias current are disabled when DIS = high). The DIS input is compatible with TTL levels regardless of whether VCC = 5V or VCC = 3.3V. The external 4.7k and 10k pull-up resistor required by most interface standards is not needed because this pin has an internal 7k resistor to VCC. The DISDLY pin is used in conjunction with the DIS pin to control bias current enable time. In normal operation the DISDLY pin should be connected to ground. In this case, each time DIS transitions from high to low the bias current will be enabled by the "slow-start" circuitry (enable time of less than 1 ms with a CAPC = 2.2 nF). 02061-DSH-001-F Mindspeed Technologies(R) Mindspeed Proprietary and Confidential 28 Functional Description For burst mode operation a capacitor C is added to the DISDLY pin, the slow-start circuitry is disabled for approximately T = 3 * 106 (sec/F) * C (F) following the DIS high transition (see figure 8). If the part is enabled (DIS transitions low) during this time the bias and modulation current will quickly return to within 90% of their final value (in less than 500ns). If DIS transitions low after the DISDLY time the slow-start circuitry will engage and the bias current will not return to its final value for approximately 1ms (depending on the CAPC capacitor value). Figure 3-7. DIS and DISDLY Timing EPON Burst Mode Operation DIS DISDLY IBIASOUT OUT+ t_off BM < 500ns t_on BM < 500ns for IMOD > 10mA Normal Operation, (slow-start whenever part enabled) DIS DISDLY t_on < 1ms, depending on CAPC IBIASOUT OUT+ t_off< 10s 02061-DSH-001-F Mindspeed Technologies(R) Mindspeed Proprietary and Confidential 29 Functional Description 3.3.9 TX Disable Control The DIS pin is used to disable the transmit signal (both the modulation and bias current are disabled when DIS = high). The DIS input is compatible with TTL levels regardless of whether VCC = 5V or VCC = 3.3V. The external 4.7k and 10k pull-up resistor required by most interface standards is not needed because this pin has an internal 7k resistor to VCC. 3.3.10 Monitor Outputs To facilitate complying with laser safety and DDMI1 requirements, output monitors are provided for transmit power (TxPwrMON) bias (BIASMON) and modulation current (MODMON). These outputs will source current proportional to the emitted optical power (TxPwrMON) the bias current (BIASMON) and modulation current (MODMON). These pins should be terminated with a resistor to ground that sets the desired full-scale voltage (not to exceed VCC3-1V). Using a monitor polarity selection (MONPOL) these monitors can be set to sink current instead of source current. They will then need to be terminated with a resistor to VCC3 and the induced voltage should not exceed 2.5V. If the outputs of these monitors are not needed, MONPOL, TxPwrMON, BIASMON, and MODMON can all be left floating and the chip current consumption will be reduced by the value of the monitor currents. 3.4 Laser Eye Safety Using this laser driver in the manner described herein does not ensure that the resulting laser transmitter complies with established standards such as IEC 825. Users must take the necessary precautions to ensure that eye safety and other applicable standards are met. Note that determining and implementing the level of fault tolerance required by the applications that this part is going into is the responsibility of the transmitter designer and manufacturer since the application of this device cannot be controlled by Mindspeed. 3.4.1 Safety Circuitry On the M02061-12 with DISDLY on pin 8, SCB is internally bonded to ground so SCB is always in a logic low state. When SCB is high the OUTP, BIASout and SVCC outputs will not be disabled when FAIL asserts (FAIL goes high). The outputs are only disabled by making DIS high. The FAIL output will also ignore much of the safety sensing circuitry when SCB is high. However, it will monitor the state of the window comparators at pin APCSET. The bias current is controlled to nominally maintain the voltage at APCSET to 1.3V. The threshold levels at the window comparators around APCSET are specified by the parameters VBH and VBL as shown in the table below. This provides the same level of eye safety protection as our previous generation of laser drivers. The current sourced out of pin APCSET is equal to the current into pin IPIN sourced from the laser monitor photo diode. If the laser is emitting excess power this will be reflected in the IPIN current and the voltage at APCSET will go high and the FAIL pin will assert. If IPIN is not connected to the laser monitor photo diode then the voltage at APCSET will fall and FAIL will assert. When SCB is low, safety circuitry in the M02061 will disable the modulation and bias current and assert the FAIL output immediately upon detecting a fault condition. In addition, the supply voltage that sources the laser (SVCC or an external switch controlled by SHDWNOUT) will immediately go open circuit and prevent any current from passing through the laser. Fault conditions checked by the M02061 include shorts to ground or VCC of all pins which can increase the laser modulation or bias current. 02061-DSH-001-F Mindspeed Technologies(R) Mindspeed Proprietary and Confidential 30 Functional Description For an initialization sequence to be successful, all the fault detection monitors must signal that the chip is "healthy". When DIS goes low, pins are checked for shorts to ground or VCC and a FAIL condition is latched if there is a fault. If the state of the pins is OK, a one-shot at the reset pin begins a countdown which will latch a FAIL condition if the bias current has not stabilized to an acceptable level during the one-shot time. The one-shot can be extended with an external capacitor connected from the RESET pin to ground. The one-shot1 width is approximately: TONE-SHOT = 3 ms + (0.3 ms/pF) x (external capacitance). Figure 3-8. Safety Circuit Block Diagram, for SCB Pin Low DIS If chip is `healthy', then Enable the outputs and Start 3msec Reset Pulse(one-shot) AND AND OUTPUT_ENABLE AND Latch for CrudeFaults VccOK Detection: SRlatch AND 5v Mode: Reset : Q Vcc Pin Set _ 5v Hi/Lo Limits FAILout (open-collector) AND Vcc3 Pin Latch for Bias_OK Delay 3.3v Hi/Lo Limits 3.3v Mode: VCC_OK Vcc Pin ONE-SHOT: t=0 RESET 5v Hi/Lo Limits Start 3ms + Tcap SRlatch Reset : Q PULSE NOTE: Pulse stays high if Reset pin is GNDed. Set _ `1' AND OR optional cap for longer T_init Vcc3 Pin 3.3v Hi/Lo Limits CrudeFaults Detection: OutP Capc MODset > 300mV > 300mV > 300mV IBout > 300mV BiasOK Detection: Window Compare: CrudeFaults_OK HI Limit MPCset OR BIAS_OK LOW Limit 1.The one-shot is actually comprised of an oscillator and 10-bit counter. 02061-DSH-001-F Mindspeed Technologies(R) Mindspeed Proprietary and Confidential 31 Functional Description 3.5 Fault Conditions when SCB is Low This section describes the M02061 operating modes during fault conditions. Over voltage, under voltage, pins shorted to VCC and pins shorted to ground are included in the fault table. Table 3-3. Circuit Response to Single-point Fault Conditions, when SCB is Low 1 2 (1 of 2) Pin Name VCC DIN+, DIN- VCC3SEL DIS Circuit Response to Over-voltage Condition or Short to VCC Circuit Response to Under-Voltage Condition or Short to Ground Bias and modulation outputs are disabled once VCC rises above the supply detection (high voltage) threshold Bias and modulation outputs are disabled once VCC drops below the supply detection (low voltage) threshold The APC loop will attempt to compensate for the change in output power. If the APC loop can not maintain the set average power, a fault state occurs.(1, 2) The APC loop will attempt to compensate for the change in output power. If the APC loop can not maintain the set average power, a fault state occurs.(1, 2) Does not affect laser power. Does not affect laser power. Bias and modulation outputs are disabled. Does not affect laser power (normal condition for circuit operation). 3.3V operation - SVCC is opened. 5V operation - SHDWNOUT goes high. FAIL Does not affect laser power. Does not affect laser power. RESET Does not affect laser power. Does not affect laser power. MODMON Does not affect laser power. Does not affect laser power. BIASMON Does not affect laser power. Does not affect laser power. TxPWRMON Does not affect laser power. Does not affect laser power. APCSET A fault state occurs.(1) A fault state occurs.(1) IPIN A fault state occurs.(1) A fault state occurs.(1) The laser will be turned off, then a fault state occurs.(1) A fault state occurs.(1) IBIASOUT OUTP Laser modulation is prevented; the APC loop will increase the A fault state occurs.(1) bias current to compensate for the drop in laser power if it is DC coupled. If the set output power can not be obtained, a fault state occurs.(1, 2) OUTN Does not affect laser power. Does not affect laser power. SVCC Does not affect laser power. Laser bias current will be shut off and a fault state occurs.(1) CAPC Laser bias current will be shut off, then a fault state occurs.(1) A fault state occurs.(1) VCC3 Bias and modulation outputs are disabled once VCC3 rises above the supply detection (high voltage) threshold Bias and modulation outputs are disabled once VCC3 drops below the supply detection (low voltage) threshold PWA Does not affect laser power. Does not affect laser power SHDWNOUT Does not affect laser power. if this pin is used to control an external switch, laser current is disabled and fault state occurs.(1) Does not affect laser power. MODSET The APC loop will attempt to compensate for the change in output power. If the APC loop can not maintain the set average power, a fault state occurs.(1, 2) A fault state occurs.(1) TCSLOPE Does not affect laser power. May affect laser power. If this is the case, the APC loop will attempt to compensate for the change in output power. If the APC loop can not maintain the set average power, a fault state occurs.(1, 2) 02061-DSH-001-F Mindspeed Technologies(R) Mindspeed Proprietary and Confidential 32 Functional Description Table 3-3. Circuit Response to Single-point Fault Conditions, when SCB is Low 1 2 (2 of 2) Pin Name Circuit Response to Over-voltage Condition or Short to VCC Circuit Response to Under-Voltage Condition or Short to Ground SCB Does not affect laser power. Does not affect laser power. DISDLY Does not affect laser power. Does not affect laser power. NOTES: 1. A fault state will assert the FAIL output, disable bias and modulation outputs and will either open the switch at SVCC (3.3V operation) or SHDWNOUT will go high (5V operation). 2. Does not affect laser power when the output is AC coupled to the laser. 02061-DSH-001-F Mindspeed Technologies(R) Mindspeed Proprietary and Confidential 33 4.0 Applications Information 4.1 General * SFP and SFF Modules * 1G/2G/4G Fibre Channel modules * Short reach and Metro SONET/SDH Figure 4-1 and Figure 4-2 illustrate typical applications for 3.3/AC coupled and 5V/DC coupled laser. VCC3 Internal 3.3V reg. VCC PWA VCC VCC SHDWNOUT Application Diagram, VCC = 3.3V Laser AC Coupled Example VCC3 Figure 4-1. VCC Internal Power Bus SVCC OUT- DIN + Input Buffer DIN- Laser Driver Output Buffer D - FF OUT+ GND0 VCC3 -1.3V IBIASOUT IPIN Input Buffer V CC (M02061-21 only) 02061-DSH-001-F CAPC DISDLY TxPwr MON BIASMON APCSET MODMON Automatic Power Control (laser bias current) MODSET TCSLOPE VCC3SEL Modulation Control SCB FAIL DIS RESET Safety Circuitry with Latched Fault TX Disable VCC3 (M02061-12 only) Mindspeed Technologies(R) Mindspeed Proprietary and Confidential 34 Applications Information Figure 4-2. Application Diagram, VCC = 5V Laser DC Coupled Example VCC Internal 3.3V reg. SHDWNOUT VCC3 V CC3 PWA VCC3 V CC VCC=5V SPST switch SVCC Internal Power Bus OUT- DIN + Input Buffer DIN- Output Buffer D - FF Laser Driver OUT+ GND0 VCC3 -1.3V IBIASOUT IPIN Input Buffer V CC (M02061-21 only) 4.2 CAPC DISDLY TxPwrMON BIASMON APCSET MODMON Automatic Power Control (laser bias current) MODSET TCSLOPE Modulation Control VCC3SEL SCB FAIL DIS RESET Safety Circuitry with Latched Fault TX Disable VCC3 (M02061-12 only) Video Operation The M02061 can be used to transmit digital video optical data even in the presence of the pathological signal. This is done by fully DC coupling the signal from the input to the laser output.In most data communications applications, AC coupling occurs at 3 points in a laser driver schematic: the data inputs, the APC control, and coupling the modulation current to the laser. In the M02061 DC coupling can be used at all 3 of these points.The data inputs can be DC coupled using PECL or CML levels (see Section 3.3.3, "Data Inputs"). LVDS signals can be DC coupled with level shifting.The APC of the bias current is controlled by feedback from the monitor photo diode in the laser package in most communications applications. In video applications this monitor photo diode should not be used if the pathological pattern may occur. Instead, the APC should be controlled in an "open loop" configuration. (Open loop simply means a monitor photo diode is not used). In the open loop configuration the APC is controlled by a resistor or a thermistor network or a look-up table. This removes AC time constants from the bias current. In Figure 4-3 the BIASmon pin is connected to the APCset pin. In this case the bias current is IBIAS = 100 x (1.3V / RAPCset). The modulation current output OUT+ can be DC coupled to the laser as shown in Figure 4-3. There are no AC time constants in the modulation current amplitude in this configuration. 02061-DSH-001-F Mindspeed Technologies(R) Mindspeed Proprietary and Confidential 35 Applications Information Figure 4-3. Video Application Block Diagram VCC Internal 3.3V reg. SHDWNOUT VCC3 V CC3 PWA VCC3 V CC VCC=5V SPST switch Internal Power Bus SVCC OUT- DIN + Input Buffer DIN- Output Buffer D - FF OUT+ Laser Driver GND0 VCC3 -1.3V IBIASOUT IPIN Input Buffer V CC (M02061-21 only) 02061-DSH-001-F CAPC DISDLY TxPwrMON BIASMON APCSET MODMON Automatic Power Control (laser bias current) MODSET TCSLOPE Modulation Control VCC3SEL SCB FAIL DIS RESET Safety Circuitry with Latched Fault TX Disable VCC3 (M02061-12 only) Mindspeed Technologies(R) Mindspeed Proprietary and Confidential 36 5.0 Package Specification Figure 5-1. QFN24 Package Information Note: View is for a 20 pin package. All dimensions in the tables apply for the 24 pin package 02061-DSH-001-F Mindspeed Technologies(R) Mindspeed Proprietary and Confidential 37 www.mindspeed.com General Information: Telephone: (949) 579-3000 Headquarters - Newport Beach 4000 MacArthur Blvd., East Tower Newport Beach, CA 92660 (c) 2010 Mindspeed Technologies(R), Inc. All rights reserved. Information in this document is provided in connection with Mindspeed Technologies(R) ("Mindspeed(R)") products. These materials are provided by Mindspeed as a service to its customers and may be used for informational purposes only. Except as provided in Mindspeed's Terms and Conditions of Sale for such products or in any separate agreement related to this document, Mindspeed assumes no liability whatsoever. Mindspeed assumes no responsibility for errors or omissions in these materials. Mindspeed may make changes to specifications and product descriptions at any time, without notice. Mindspeed makes no commitment to update the information and shall have no responsibility whatsoever for conflicts or incompatibilities arising from future changes to its specifications and product descriptions. No license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted by this document. THESE MATERIALS ARE PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESS OR IMPLIED, RELATING TO SALE AND/OR USE OF MINDSPEED PRODUCTS INCLUDING LIABILITY OR WARRANTIES RELATING TO FITNESS FOR A PARTICULAR PURPOSE, CONSEQUENTIAL OR INCIDENTAL DAMAGES, MERCHANTABILITY, OR INFRINGEMENT OF ANY PATENT, COPYRIGHT OR OTHER INTELLECTUAL PROPERTY RIGHT. MINDSPEED FURTHER DOES NOT WARRANT THE ACCURACY OR COMPLETENESS OF THE INFORMATION, TEXT, GRAPHICS OR OTHER ITEMS CONTAINED WITHIN THESE MATERIALS. MINDSPEED SHALL NOT BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING WITHOUT LIMITATION, LOST REVENUES OR LOST PROFITS, WHICH MAY RESULT FROM THE USE OF THESE MATERIALS. Mindspeed products are not intended for use in medical, lifesaving or life sustaining applications. Mindspeed customers using or selling Mindspeed products for use in such applications do so at their own risk and agree to fully indemnify Mindspeed for any damages resulting from such improper use or sale. 02061-DSH-001-F Mindspeed Technologies(R) Mindspeed Proprietary and Confidential 38