MAX3735A: Laser Driver Output Configurations, Part 1: DC-Coupled Optimization Techniques


The MAX3735A is a DC-coupled SFP laser driver designed for data rates up to 2.7Gbps. The multi-rate capability, small package, APC loop, SFP safety/timing specifications and monitor outputs of the MAX3735A make it suitable for a large variety of optical module applications operating over a wide range of data rates. This design note (Part 1 of a series of notes) will discuss the DC-coupled interface in detail. The output of the MAX3735A is intended to drive DC-coupled, edge-emitting lasers, but it can also drive AC-coupled and differentially driven, edge-emitting lasers. The MAX3735A can also be configured to drive common-anode VCSELs. The output configurations will be detailed in future parts of this design note series on coupling interfaces. The purpose of these notes is to discuss the advantages and disadvantages of the various output configurations, and to provide schematics and examples that will help module designers choose the optimal output structure for their application. The MAX3735A will be used as an example to discuss these interfaces, but the techniques can be applied to other laser drivers such as the MAX3737, MAX3735, and MAX3656, due to their similar output structures. Read full article.