APPLICATION NOTE 3887

MAX3643: Using the MAX3643 Laser Driver with a Low-Cost Microcontroller


Abstract: The MAX3643 compact burst mode laser driver is designed for PON (Passive Optical Network) applications. There are many different types of PON networks in deployment such as APON, BPON, GPON, GEPON and EPON. The specifics of each of these types of PONs is not important to this discussion other than noting that they all share a few common qualities with respect to the laser driver needed in the ONT. The MAX3643 offers some customers the potential of a lower cost system by allowing them to use already available microcontroller features (available in a physical layer controller or a MAC layer controller) to adjust the laser currents. The total driver and controller costs can be reduced by taking the laser controller circuits out of the laser driver, which is typically done on a high-speed BiPOLAR or BiCMOS process (for best high-speed performance), and placing the control into a low-cost CMOS microcontroller. This application note discusses some common techniques for digital laser control that can be incorporated into a low-cost microcontroller or an available system controller. Examples and test data are also provided showing the typical performance of such methods.