Rev 0; 2/06 XFP Laser Control and Digital Diagnostic IC The DS1862 is a closed-loop laser-driver control IC with built-in digital diagnostics designed for XFP MSA. The laser control function incorporates average power control (APC) and allows extinction ratio control though a temperature indexed look-up table (LUT). The DS1862 monitors up to seven analog inputs, including temperature and monitor diode (MD) current, which are used to regulate the laser bias current and extinction ratio.
DS1862 XFP Laser Control and Digital Diagnostic IC ABSOLUTE MAXIMUM RATINGS Voltage on Any Open-Drain Pin Relative to Ground.............................................-0.5V to +6.0V Voltage on MOD-DSEL, SDA, SCL, FETG, THRSET, TX-D, AUX1MON, AUX2MON, IBIASMON, RSSI, BIASSET, MODSET, EN1, and EN2 ............-0.5V to (VCC3 + 0.5V), not to exceed +6.0V Voltage on SC-RX-LOS, SC-RX-LOL, RX-LOS, SC-TX-LOS, MOD-NR, EN1, and EN2 ............-0.5V to (VCC2 + 0.5V), not to exceed +6.
XFP Laser Control and Digital Diagnostic IC (VCC3 = +2.9V to +5.5V, VCC2 = +1.6V to +3.6V, TA = -40°C to +100°C, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 3 5 mA Supply Current ICC3 P-DOWN/RST = 1 High-Level Output Voltage (FETG) VOH IOH (max) = -2mA VCC3 0.
DS1862 XFP Laser Control and Digital Diagnostic IC I2C AC ELECTRICAL CHARACTERISTICS (VCC3 = +2.9V to +5.5V, TA = -40°C to +100°C, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 400 kHz SCL Clock Frequency fSCI 0 Clock Pulse-Width Low tLOW 1.3 µs Clock Pulse-Width High tHIGH 0.6 µs Bus Free Time between STOP and START Conditions tBUF 1.3 µs Start Hold Time tHD:SDA 0.6 µs Start Setup Time tSU:SDA 0.
XFP Laser Control and Digital Diagnostic IC (VCC3 = +2.9V to +5.5V, VCC2 = +1.6V to +3.6V, TA = -40°C to +100°C, unless otherwise noted.) PARAMETER SYMBOL IMODSET Accuracy IMODSET DNL IMODSET INL IMODSET Temp Drift IMODSET Voltage Drift IMODSET FS Accuracy APC Bandwidth CONDITIONS +25°C IMODSET = 0.04mA to 1.2mA 75µA range 150µA range 300µA range 600µA range 1200µA range 75µA range 150µA range 300µA range 600µA range 1200µA range IMD / IAPC = 1 (Note 4) MIN TYP MAX UNITS -1.5 +1.5 % -0.9 -0.
DS1862 XFP Laser Control and Digital Diagnostic IC AC ELECTRICAL CHARACTERISICS—SOFT* CONTROL AND STATUS (VCC3 = +2.9V to +5.5V, VCC2 = +1.6V to +3.6V, TA = -40°C to +100°C, unless otherwise noted.
XFP Laser Control and Digital Diagnostic IC (VCC3 = +2.9V to +5.5V, VCC2 = +1.6V to +3.6V, TA = -40°C to +100°C, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS HIGHBIAS and TX-P Threshold FS (Note 10) VCC2/3 Fault Asserted Falling Edge Delay ↓ VCC2/3 (Note 11) QT Temperature Coefficient MIN TYP MAX UNITS 2.48 2.5 2.52 mA 75 ms -3 QT Voltage Coefficient QT FS Trim Accuracy (4.2V, +25°C) QT Accuracy (Trip) (INL) 2.480 2.500 -2 0 % %/V 2.520 mA +2 LSB 0.5 %/V 1.
XFP Laser Control and Digital Diagnostic IC DS1862 Timing Diagrams RESET-DONE VCC > VPOA READ-FLAGS READ-FLAGS TX-D P-DOWN/RST RESET-DONE INTERRUPT tPDR-OFF IBIASSET tINIT tINIT OFF tINIT tINIT ON IMODSET Figure 1. Power-On Initialization with P-DOWN/RST Asserted and TX-D/SOFT-TX-D Not Asserted VCC > VPOA READ-FLAGS TX-D RESET-DONE P-DOWN/RST INTERRUPT IBIASSET tINIT ON tINIT OFF tINIT IMODSET Figure 2.
XFP Laser Control and Digital Diagnostic IC TX-F TX-D IBIASSET tOFF tON IMODSET Figure 3. TX-D Timing During Normal Operation OCCURRENCE OF FAULT FETG TX-D IBIASSET tFAULT IMODSET Figure 4.
XFP Laser Control and Digital Diagnostic IC DS1862 Timing Diagrams (continued) OCCURRENCE OF FAULT P-DOWN/RST tRESET FETG tINIT IBIASSET RESET-DONE IMODSET Figure 5. Successful Recovery from Transient Safety Fault Condition Using P-DOWN/RST RESET-DONE OCCURRENCE OF FAULT tFAULT P-DOWN/RST tRESET tFAULT FETG (FETG_POL = 1) IBIASSET IMODSET Figure 6.
XFP Laser Control and Digital Diagnostic IC OCCURRENCE OF MONITOR CHANNEL FAULT tINIT_ON INTERRUPT tINIT_OFF READ FLAGS Figure 7.
Typical Operating Characteristics (TA = +25°C, unless otherwise noted.) 3.5 3.0 SRC_SINK_B = 0 IBMD = 499.479µA 2.8 3.3 3.8 4.3 4.8 4.5 4.0 -15 -40 SUPPLY VOLTAGE (V) IBMD DRIFT vs. SUPPLY VOLTAGE IMODSET DRIFT (%) SRC_SINK_B = 0 0.2 0 -0.2 SRC_SINK_B = 1 -0.4 -0.6 35 60 IBMD = 499.479µA -1.0 2.8 3.6 4.4 10 35 60 IMODSET DRIFT vs. TEMPERATURE INTEGRAL NONLINEARITY OF QUICK TRIPS 0.8 0.6 0 -0.5 -1.0 0.2 0 -0.2 -0.4 VCC3 = 5.5V, VCC2 = 1.6V -2.
XFP Laser Control and Digital Diagnostic IC NAME PIN DESCRIPTION P-DOWN/RST A1 Power-Down/Reset Input. This multifunction pin is pulled high internally. See the Power-Down/Reset Pin section for additional information. SC-RX-LOS A2 Signal Conditioner Receiver Loss-of-Signal Input. This pin is an active-high input with LVCMOS/LVTTL voltage levels. SC-RX-LOL A3 Signal Conditioner Receiver Loss-of-Lock Input. This pin is an active-high input with LVCMOS/LVTTL voltage levels.
XFP Laser Control and Digital Diagnostic IC DS1862 Block Diagram VCC2 VCC3 TEMPERATURE SENSOR INT ALARM AND WARNING THRESHOLDS COMPARATORS INTERRUPT BMD OFFSET RIGHT SHIFTING AUX1MON ADC 13 BIT MUX RSSI GAIN IBIASMON AUX2MON WARNING FLAGS ALARM FLAGS MASKING BITS I TO V ALARM FLAGS TX-P VCC3 VCC3 VCC2 VCC2 MEASURED DATA DS1862 ADDRESS R/W DATA BUS MISC CONTROL SIGNALS MASKING BITS ALARM AND WARNING THRESHOLDS WARNING FLAGS IBMD INTERRUPT TABLE 01h SERIAL ID DATA LOWER MEMORY
XFP Laser Control and Digital Diagnostic IC The DS1862’s block diagram is described in detail within the following sections and memory map/memory description. Automatic Power Control (APC) The DS1862’s APC is accomplished by closed-loop adjustment of the bias current (BIASSET) until the feedback current (BMD) from a photodiode matches the value determined by the APC registers. The relationship between the APC register and IBMD is given by: IBMD = 5.859µA x APCC<7:0> + (1.
DS1862 XFP Laser Control and Digital Diagnostic IC If the largest current range is selected, the maximum value of FFh (from LUT) corresponds to a 1200µA sink current. Regardless of current range, the MODSET value always consists of 256 steps, including zero. IMODSET can be controlled automatically with the temperature-based look-up table, or by three other manual methods. Automatic temperature addressed look-up is accomplished by an internal or external temperature sensor controlling an address pointer.
XFP Laser Control and Digital Diagnostic IC Measuring Temperature—Internal or External The DS1862 is capable of measuring temperature on three different monitor channels: internal temperature sensor, AUX1MON, and AUX2MON. Only the internal temperature and AUX2MON channels are capable of indexing the LUT to control the extinction ratio. To use an external temperature sensor on AUX2MON, the TEMP_INT/EXT bit in Table 04h, Byte 8Bh, must be set.
DS1862 XFP Laser Control and Digital Diagnostic IC fault functionality, current on the BIASSET pin is monitored by the DS1862 to control the HIGHBIAS quick trip. Similar to TX-P, the RSSI pin is used to measure the received power, RX-P. required to get the binary value to match the measured quantity. A table of acceptable units and/or their corresponding user-programmable 4-bit op-code is provided below.
XFP Laser Control and Digital Diagnostic IC MSB (BIN) LSB (BIN) TEMPERATURE (°C) 01000000 00000000 +64 01000000 00001000 +64.03215 01011111 00000000 +95 11110110 00000000 -10 11011000 00000000 -40 loaded into the appropriate channels’ Gain register. This requires forcing two known voltages on to the monitor input pin. For best results, one of the forced voltages should be the NULL input and the other should be 90% of FS.
DS1862 XFP Laser Control and Digital Diagnostic IC /* Assume that the Null input is 0.5V. */ /* In addition, the requirement for LSB is 50µV. */ FS = 65536 * 50e-6; /* 3.2768 */ CNT1 = 0.5 / 50e-6; /* 10000 */ CNT2 = 0.90*FS / 50e-6; /* 58982 */ /* Thus the NULL input of 0.5V and the 90% of FS input is 2.94912V. */ set the trim-offset-register to zero; set Right-Shift register to zero (Typically zero.
XFP Laser Control and Digital Diagnostic IC The DS1862 is capable of generating an alarm and/or warning whenever an analog monitored channel goes out of a user-defined tolerance. Temperature, bias current (based on IBIASMON), receive power (based on RSSI), AUX1MON, AUX2MON, and VCC2/3, are moni- tored channels that generate latched flags. See the figure below for more detail pertaining to AUX1MON and AUX2MON.
Warning and Alarm Logic Based on Signal Conditioners The DS1862 also has flags that are set by certain logical conditions on signal conditioner (SC) pins: SC-RX-LOL, SC-RX-LOS, SC-TX-LOS. Similarly, for each latched signal conditioner flag there are also mask bits that are capable of preventing the alarm or warning flag from causing an INTERRUPT pin to assert. Again, flags are cleared automatically whenever their memory address is read. See Figure 11 for more detail.
XFP Laser Control and Digital Diagnostic IC DS1862 LATCH SHUTDOWN LOGIC ADC QT LOW TX-P FLAG THRESHOLD BMD (PIN) (TX-P CURRENT) LOW TX-P MASK ADC QT HIGH TX-P FLAG THRESHOLD BIASSET (PIN) (BIASSET CURRENT) FETG (PIN) HIGH TX-P MASK ADC QT BIAS HIGH FLAG THRESHOLD SOFT TX-D P-DOWN/RST (PIN) TX-D (PIN) SAFETY FLAG SOFT P-DOWN/RST FETG_POL BIAS HIGH MASK SHUTDOWN FLAG QT LOW TX-P FLAG QT HIGH TX-P FLAG QT BIAS HIGH FLAG FETG_POL 0 DRIVE A P-CHANNEL SWITCH 1 DRIVE A N-CHANNEL SWITCH LATC
DS1862 XFP Laser Control and Digital Diagnostic IC During an asserted period of P-DOWN/RST (DS1862 in power-down), and VCC3 is cycled, the DS1862 remains in power-down mode upon power-up. While in powerdown mode the INTERRUPT pin does not assert. Once VCC3 has returned, the reset done flag asserts after the interrupt assert delay, tINIT ON. Reset Functionality Besides powering down the DS1862, the P-DOWN/RST pin also functions to reset the DS1862.
XFP Laser Control and Digital Diagnostic IC DS1862 DEC hex 0 0 I2C SLAVE ADDRESS A0h 00h LOWER MEMORY DIGITAL DIAGNOSTIC FUNCTIONS PASSWORD ENTRY (PWE) (4 BYTES) 127 7F 128 80 TABLE SELECT BYTE 7Fh 80h 80h 80h USER EEPROM DATA TABLE 05h TABLE 04h TABLE 01h TABLE 00h XFP MSA SERIAL ID DATA 80h 80h TABLE 03h TABLE 02h MODULATION DAC LUT OPTIONAL SCALE VALUES AND THRSET CONTROL CONTROL AND CONFIGURATION TABLE (72 BYTES) 87h BBh C7h 220 DC 255 FF MISC CONTROL BITS FFh FFh Figure 1
DS1862 XFP Laser Control and Digital Diagnostic IC LOWER MEMORY (00H–7FH) ADDRESS (hex) 00<0,2> 08<2> WORD 0 BYTE 0/8 EE WORD 1 BYTE 1/9 BYTE 2/A Signal Cond Temp Warn Lo WORD 2 BYTE 4/C BYTE 3/B Temp Alarm Hi VCC3 Alarm Hi* WORD 3 BYTE 5/D BYTE 6/E Temp Alarm Lo VCC3 Alarm Lo* BYTE 7/F Temp Warn Hi VCC3 Warn Hi* 10<2> VCC3 Warn Lo* Bias Alarm Hi Bias Alarm Lo Bias Warn Hi 18<2> Bias Warn Lo TX-P Alarm Hi TX-P Alarm Lo TX-P Warn Hi 20<2> TX-P Warn Lo RX-P Alarm Hi RX-P Alarm Lo
XFP Laser Control and Digital Diagnostic IC Bit6* Bit5 Bit4 Bit3 Bit2 Bit1 Bit0** BYTE (hex) BYTE/WORD NAME 57 <1> L-HI-VCC5-W L-LO-VCC5-W L-HI-VCC3-W L-LO-VCC3-W L-HI-VCC2-W L-LO-VCC2-W L-HI-VEE5-W L-LO-VEE5-W 58 <1> HI-TEMP-AL LO-TEMP-AL MASK MASK 59 <1> HI-RX-P-AL MASK 5A <1> 5B <1> 5C <1> 5D <1> APD-SUP-F TEC-F MASK MASK 5E <1> 5F 6E bit15 bit14 bit13 bit12 bit11 bit10 bit9 bit8 bit7 bit6 bit4 bit2 bit1 bit0 LO-TX-P-AL MASK LO-RX-P-AL HI-AUX1-AL LO-AUX1-AL HI
DS1862 XFP Laser Control and Digital Diagnostic IC TABLE 01H (SERIAL ID MEMORY) WORD 0 WORD 1 WORD 2 WORD 3 ADDRESS (hex) Byte 0/8 Byte 1/9 Byte 2/A Byte 3/B Byte 4/C Byte 5/D Byte 6/E Byte 7/F 80<2> EE EE EE EE EE EE EE EE 88<2> EE EE EE EE EE EE EE EE 90<2> EE EE EE EE EE EE EE EE 98<2> EE EE EE EE EE EE EE EE A0<2> EE EE EE EE EE EE EE EE A8<2> EE EE EE EE EE EE EE EE B0<2> EE EE EE EE EE EE EE EE B8<2> EE EE EE EE EE EE
XFP Laser Control and Digital Diagnostic IC WORD 1 WORD 2 WORD 3 Byte 0/8 Byte 1/9 Byte 2/A Byte 3/B Byte 4/C Byte 5/D Byte 6/E Byte 7/F 80<4> Reserved Bias shift, TX-P shift RX-P shift AUX1 shift AUX2 shift Reserved APC course setting APC fine setting LUT current range Control Register 1 88<4> Quick trip TX-P high Quick trip TX-P low QT high bias setting Control Register 2 Reserved Reserved Reserved Reserved 90<4> Reserved Reserved Scale MSB VCC3 Scale LSB VCC3 Scale MSB B
DS1862 XFP Laser Control and Digital Diagnostic IC TABLE 05H (OPTIONAL OFFSETS AND THRSET) ADDRESS (hex) WORD 0 Byte 0/8 80–87 WORD 1 Byte 1/9 Byte 2/A DS60 SCALE WORD 2 Byte 3/B LM50 SCALE WORD 3 Byte 4/C Byte 5/D Byte 6/E Byte 7/F Reserved Reserved Reserved VTH DAC Value <1> EXPANDED BYTES Bit7 Bit6 Bit5 BYTE (hex) BYTE/WORD NAME bit15 80 DS60 SCALE <5> 215 214 213 212 211 82 LM50 SCALE <5> 215 214 213 212 211 87 VTHRSET_Value 27 bit14 bit13 bit12 26 bit11 bit1
XFP Laser Control and Digital Diagnostic IC DS1862 Bit 0: DATA_NOT_READY. Bit is high until DS1862 has achieved power-up. Bit goes low, signaling that monitor channel data is ready to be read. Bit 1: RX-LOS. Indicates optical loss of the signal and is updated within tLOS-ON. Bit 2: Interrupt. Indicates the state of the INTERRUPT pin and is updated within tINIT ON. Bit 3: Soft P-DOWN/RST. R/W bit that places the DS1862 in power-down mode. Toggle to reset. Bit 4: P-DOWN/RST.
DS1862 XFP Laser Control and Digital Diagnostic IC DDh • 6Eh Enable ......................< R-all / W-Module ><00> If bit 5 is high, then bit 3 of 6Eh is not masked. If bit 6 is high, then bit 6 of 6Eh is not masked. Bit 0 is the Lock_Bit. If set, Lower Memory address 01h, bit 0 is writable. DEh • AUX1/2 Unit Sel ...............< R-all / W-Module ><00> These two 4-bit values define what is being meausred on AUX1MON and AUX2MON.
XFP Laser Control and Digital Diagnostic IC • APC REF FINE .................< R-Module / W-Module ><00> This 2-bit value in <1:0> sets the fine APC current on BMD. The MSB is bit 6. 86h • LUT Range.......................< R-Module / W-Module ><00> This 3-bit register in <2:0> sets the current range on MODSET. The MSB is bit 2. 87h • Control Reg1....................< R-Module / W-Module ><00> Bit 0: Reserved. Bit 1: SRC_SNK_B.
DS1862 XFP Laser Control and Digital Diagnostic IC 92h VCC2/3 SCALE ...........................< R-Module / W-Module > register controls the scale value for the VCC2/3 monitor channel. 94h • BIAS SCALE.....................< R-Module / W-Module > register controls the scale value for the BIAS monitor channel. 96h • TX-P SCALE .....................
XFP Laser Control and Digital Diagnostic IC Bit 0: AEN. A high on AEN enables data placed in the LUT Value register to drive MODSET. Bit 1: TEN. A high on TEN enables the LUT index pointer to fetch data from the LUT. Bit 2: SEEB. A high on SEEB disables EEPROM writes of Shadowed EEPROM locations. Bit 3: Reserved. Bit 4: Reserved. Bit 5: Reserved. Bit 6: Reserved. Bit 7: Reserved. B4h • DAC STATUS ...................< R-Module / W-Module > Bit 0: Reserved. Bit 1: Reserved.
DS1862 XFP Laser Control and Digital Diagnostic IC Security/Password Protection The DS1862 features two separate and independent 32-bit passwords for important memory locations. The host password and the module password allow their own allocated memory locations to be locked to prevent write and/or read access. To enhance the security of the DS1862, the Password Entry and Setting bytes can never be read.
XFP Laser Control and Digital Diagnostic IC ter are done according to the bit write definition and the acknowledgement is read using the bit read definition. Byte read: A byte read is an 8-bit information transfer from the slave to the master plus a 1-bit ACK or NACK from the master to the slave.
DS1862 XFP Laser Control and Digital Diagnostic IC The memory address is always the second byte transmitted during a write operation following the slave address byte. I2C Communication Writing a single byte to a slave: The master must generate a start condition, write the slave address byte (R/W = 0), write the memory address, write the byte of data, and generate a stop condition. Remember the master must read the slave’s acknowledgement during all byte write operations.
XFP Laser Control and Digital Diagnostic IC DS1862 COMMUNICATIONS KEY S START A ACK WHITE BOXES INDICATE THE MASTER IS CONTROLLING SDA P STOP N NOT ACK SHADED BOXES INDICATE THE SLAVE IS CONTROLLING SDA SR REPEATED START X X X 0 0 0 X X X X X NOTE: ALL BYTES ARE SENT MOST SIGNIFICANT BIT FIRST. THE FIRST BYTE SENT AFTER A START CONDITION IS ALWAYS THE SLAVE ADDRESS FOLLOWED BY THE READ/WRITE BIT.
DS1862 XFP Laser Control and Digital Diagnostic IC CRC-8 includes and requires the explicit starting memory address to be included as the second transferred byte. Next, the master transfers the data as the DS1862 acknowledges. Only 4 bytes can be sequentially written during one transmission while using PEC. After the master writes the intended number of bytes, the CRC-8 value should be transmitted. Following the CRC-8 byte the master should transmit the CAB byte (CRC Add-on Byte).
XFP Laser Control and Digital Diagnostic IC SDA and SCL Pullup Resistors SDA is an open-collector bidirectional data pin on the DS1862 that requires a pullup resistor to realize high logic levels. Either an open-collector output with a pullup resistor or a push-pull output driver can be utilized for the SCL input. Pullup resistor values should be chosen to ensure that the rise and fall times listed in the AC Electrical Characteristics are within specification. Typical Operating Circuit 1.8V 3.3V 0.
DS1862 XFP Laser Control and Digital Diagnostic IC Chip Topology TRANSISTOR COUNT: 75,457 SUBSTRATE CONNECTED TO GROUND Package Information For the latest package outline information, go to www.maxim-ic.com/DallasPackInfo. Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
