11.3 Gbps laser diode driver for SFP+ optical modules
The Maxim Integrated MAX3949ETE+ is a single-channel laser diode driver rated for 11.3 Gbps operation, designed to drive a differential-modulated laser in 10G SFP+ optical transceivers. It delivers a bias current up to 105 mA and a modulation current up to 85 mA, with a supply range of 2.95 V to 3.63 V. The part is specified over -40°C to 95°C, suiting it for industrial-temperature telecom and datacom equipment where the optics cage sees ambient heat from adjacent line cards.
Package and rework — 16-TQFN with exposed pad
Housed in a 16-lead WFQFN with an exposed pad (3 mm x 3 mm TQFN footprint), this package is a standard for high-speed laser drivers where the thermal pad must be soldered to a ground-plane via array to pull heat out of the die. The exposed pad is the primary thermal path — without a proper via stitch under the pad, junction temperature climbs fast at 85 mA modulation continuous. It is an MSL 1 part out of the bag, so no bake is needed before reflow if the sealed pouch is intact.
Lifecycle and sourcing reality
The MAX3949ETE+ carries an Active product status per the manufacturer, with ROHS3 compliance. No immediate obsolescence risk, but as with any high-speed analog IC, it is worth checking the manufacturer's PCN page annually for die shrinks or assembly site changes that could affect RF performance.
What the modulation and bias ratings mean for the BOM
The 105 mA bias current ceiling and 85 mA modulation current define the laser diode types this driver can handle. For a typical 10Gbps DFB laser, the MAX3949ETE+ has headroom.