The HXT4101A VCSEL driver is a key component for compact, high-performance, low-power optical modules. In conjunction with the VCSEL, the chip handles the complete digital-to-optical conversion, including CML input, laser driver, drive control, and supervision. The HXT4101A can be used in standalone mode (no microcontroller need), or in an I2C-controlled mode. The I2C interface and the embedded monitoring circuits enable fully programmable OSAs with co-packaged VCSEL and driver, for example low-power SFP+ modules using Smart TO-cans®. Both operational modes require a small number of additional components resulting in low cost, compact, high yield assemblies.