19-5755; Rev 0; 2/11 MAX3946 Evaluation Kit The MAX3946 evaluation kit (EV kit) is an assembled demonstration board that provides optical evaluation of the MAX3946 1.0625Gbps to 11.3Gbps laser driver. The controlling software communicates with the EV kit through the USB port and provides simplified control of all the device functions. The EV kit can be fully powered by the USB port, or the user can choose to power the device by a single external 3.3V supply while the USB port supplies the on-board microcontroller. The flex-cable connection on the EV board allows attachment of lasers incorporating flex cables. Features S Drives Differential-Connected Lasers S Software Control of the MAX3946 S Power Supplied Through USB or External Connection Ordering Information PART TYPE MAX3946EVKIT EV Kit EV Kit Contents S MAX3946 EV Kit Board Component List DESIGNATION QTY DESCRIPTION DESIGNATION QTY L10, L14, L15, L16 4 10FH Q10% inductors (0603) 0.1FF Q20% ceramic capacitors (0204) R1, R2 2 1.00kI Q1% resistors (0402) R3 1 680I Q5% resistor (0402) 3 10FF Q10% ceramic capacitors (0805) R5, R6 2 20I Q5% resistors (0603) R7, R8 2 100I Q5% resistors (0603) 0 Not installed R15, R50 2 4.7kI Q5% resistors (0402) C21, C22 2 33pF Q10% ceramic capacitors (0402) R16, R17 2 1kI Q5% resistors (0402) C25, C26, C27, C49, C52 0.1FF Q10% ceramic capacitors (0402) 5 51I Q5% resistors (0402) 5 R18, R52, R55, R66, R73 R24 1 1.5kI Q5% resistor (0402) C34, C55 2 1FF Q10% ceramic capacitors (0603) R31, R51, R53 3 10kI Q5% resistors (0402) SW1 1 SPDT switch C35, C37, C38 3 4.7FF Q10% ceramic capacitors (0805) U1 1 D6 1 Green LED 1.0625Gbps to 11.3Gbps, SFP+ laser driver (24 TQFN-EP*) Maxim MAX3946ETG+ J1, J2 2 SMA edge-mount connectors U2 1 Low-noise LDO regulator (8 TDFN-EP*) Maxim MAX8902AATA+ U6 0 User-supplied TOSA U10 1 Microcontroller (28 SO) Microchip PIC16C745-I/SO Y2 1 6MHz crystal ECS Inc. ECS-60-32-5PXDN -- 1 PCB: MAX3946 EVALUATION BOARD, REV A C1-C6, C8, C9, C16, C41 10 0.01FF Q10% ceramic capacitors (0402) C7, C10, C12, C14 4 C11, C13, C15 C17-C20 J3, J4, TP3, TP7, TP10-TP13 8 Test points J8 1 USB connector JU2 1 2 x 6 header, 0.1in centers L1 1 22FH Q20% inductor Taiyo Yuden CBC3225T220M L2, L3 2 18nH Q2% inductors (0402) L4, L11, L12 3 Ferrite beads (0402) Murata BLM15GG471 DESCRIPTION *EP = Exposed pad. ________________________________________________________________ Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com. Evaluates: MAX3946 General Description Quick Start Note: In the following sections, software-related items are identified by bolding. Text in bold refers to items directly from the EV kit software. Text in bold and underlined refers to items from the WindowsM operating system. 1) Solder a laser to connection U6. See Figure 1 for more information about the laser connection. 2) Set SW1 to the desired power-supply option (USB or external supply). 3) If an external power supply is used, set the voltage to 3.3V, the current limit to 300mA, and connect the supply to the board. 4) To download the latest version of the EV kit software (MAX3946Rev1.ZIP), visit the Maxim website at www.maxim-ic.com/evkitsoftware. Unzip the file to a local folder and run the installation file (setup. EXE). Installation requires administrative rights and can also require Internet access to download necessary drivers. 5) After installation is complete, follow this path to start the program: StartAll Programs MAX3946EVGUIMAX3946EVGUI. 6) Connect the computer to the EV kit with a USB cable (A-male to Mini-B-male). LED D6 should illuminate, indicating that USB power is detected. Click the USB Connect button in the software to initiate communication to the EV kit. The Status indicator turns green when communication is established. 7) Connect a 50I source to TIN- and TIN+ (J1 and J2). Set the source differential amplitude to 500mVP-P. 8) Connect the output from the TOSA to an optical receiver (optical-to-electrical converter or optical input head on an oscilloscope). 9) All device controls are available in the software. Fault and warning indicators are displayed on the right side of the graphical user interface (GUI) window. When a hard fault has occurred the device goes into latched shutdown. The source of the fault should be removed and the DISABLE checkbox should be toggled to reset the part. 10) The registers contain a default setting and can be read using the Tx Read All button. For detailed register functions, refer to the MAX3946 IC data sheet. 11) To enable the part, the DISABLE checkbox should be toggled (checked and then unchecked) and the Tx Enable checkbox should be checked. After doing this, click the Tx Read All button twice and verify whether any faults are indicated. All fault indicators should be green if everything is set up properly. 12) The Tx De-emphasis Control edit box can be used to adjust the eye diagram. After choosing a new setting, click the Tx De-emphasis Control edit box Load button followed by the IMod edit box Load button. Doing so loads the new preemphasis setting to the modulation current driver. Further improvements to the eye diagram can be accomplished by adjusting the component values of L2, L3, L11, L12, and R5-R8. 1 N.C. GND LD CATHODE LD ANODE GND U6 N.C. Evaluates: MAX3946 MAX3946 Evaluation Kit Figure 1. TOSA Connection Windows is a registered trademark of Microsoft Corp. 2 _______________________________________________________________________________________ MAX3946 Evaluation Kit Evaluates: MAX3946 Figure 2. MAX3946 EV Kit Software Detailed Description of Software Graphical User Interface (GUI) The GUI consists of three main blocks: bias and modulation control, data path adjustments, and fault indicators. Bias and Modulation Control For bias and modulation current there are three controls: set current, set maximum, and increment. The left-side data-entry boxes allow the user to write to the SET_IBIAS or SET_IMOD register directly, as long as that value is below the value loaded in the IBIASMAX and IMODMAX registers. The middle data-entry boxes allow the user to write to the IBIASMAX and IMODMAX registers. The right-side data-entry boxes allow the user to increment or decrement the bias and modulation current registers over a Q15 LSB range by writing to the BIASINC and MODINC registers. The appropriate Load button must be clicked to initiate a register write. The Read buttons read and display the values held in the SET_IBIAS/ SET_IMOD, IBIASMAX/IMODMAX, and BIASINC/MODINC registers. Calculated bias and modulation current values are displayed below the data-entry boxes. The modulation current is calculated based on the laser's effective series resistance provided by the user in the Laser Resistance (Rld) edit box. Data Path Adjustments This block allows control of preemphasis, the input equalization, data polarity, and pulse-width adjustment. The Tx De-emphasis Control edit box has a pull-down box with four options for setting the TXDE_MD bits in the TXCTRL register. When manual control is selected, the De-emphasis edit box becomes available to write values to the SET_TXDE register. When the Tx Polarity checkbox is checked the TOUT+ pin sinks current when TIN+ is high (typical setup). The output polarity is inverted if the box is unchecked. Check the Tx Equalizer Enable checkbox to enable the input equalizer. Once checked, the Tx EQ Control edit box becomes available to write to the SET_TXEQ register. Fault Indicators Along the right-hand side of the GUI are fault indicators that show the status of the TXSTAT1 and TXSTAT2 registers. Hard faults disable the device and require a toggling of the DISABLE checkbox to restart the device (once the source of the fault has been removed). Soft faults operate as warnings, but do not disable the part. Automatic updating of the fault monitors can be enabled by checking the Auto Read Monitors checkbox. _______________________________________________________________________________________ 3 Evaluates: MAX3946 MAX3946 Evaluation Kit Figure 3. MAX3946 EV Kit Schematic 4 _______________________________________________________________________________________ MAX3946 Evaluation Kit Evaluates: MAX3946 Figure 4. MAX3946 EV Kit Component Placement Guide--Component Side _______________________________________________________________________________________ 5 Evaluates: MAX3946 MAX3946 Evaluation Kit Figure 5. MAX3946 EV Kit PCB Layout--Top Side 6 _______________________________________________________________________________________ MAX3946 Evaluation Kit Evaluates: MAX3946 Figure 6. MAX3946 EV Kit PCB Layout--Ground Plane _______________________________________________________________________________________ 7 Evaluates: MAX3946 MAX3946 Evaluation Kit Figure 7. MAX3946 EV Kit PCB Layout--Power Plane 8 _______________________________________________________________________________________ MAX3946 Evaluation Kit Evaluates: MAX3946 Figure 8. MAX3946 EV Kit PCB Layout--Solder Side _______________________________________________________________________________________ 9 Evaluates: MAX3946 MAX3946 Evaluation Kit Figure 9. MAX3946 EV Kit Component Placement Guide--Solder Side 10 MAX3946 Evaluation Kit REVISION NUMBER REVISION DATE 0 2/11 DESCRIPTION Initial release PAGES CHANGED -- 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. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2011 Maxim Integrated Products 11 Maxim is a registered trademark of Maxim Integrated Products, Inc. Evaluates: MAX3946 Revision History Mouser Electronics Authorized Distributor Click to View Pricing, Inventory, Delivery & Lifecycle Information: Maxim Integrated: MAX3946EVKIT+