19-3118; Rev 3; 1/10
3.2Gbps SFP VCSEL Driver with Diagnostic
The MAX3740A is a high-speed VCSEL driver for small-
form-factor (SFF) and small-form-factor pluggable (SFP)
fiber optic LAN transmitters. It contains a bias genera-
tor, a laser modulator, and comprehensive safety fea-
tures. The automatic power control (APC) adjusts the
laser bias current to maintain average optical power
over changes in temperature and laser properties. The
driver accommodates common cathode and differential
The MAX3740A operates up to 3.2Gbps. It can switch
up to 15mA of laser modulation current and source up
to 15mA of bias current. Adjustable temperature com-
pensation is provided to keep the optical extinction
ratio within specifications over the operating tempera-
ture range. The MAX3740A interfaces with the Dallas
DS1858 to meet SFF-8472 timing and diagnostic
requirements. The MAX3740A accommodates various
VCSEL packages, including low-cost TO-46 headers.
The MAX3740A safety circuit detects faults that could
cause hazardous light levels and disables the VCSEL
output. The safety circuits are compliant with SFF and
SFP multisource agreements (MSA).
The MAX3740A is available in a compact 4mm ✕ 4mm,
24-pin thin QFN package and operates over the -40°C
to +85°C temperature range.
Multirate (1Gbps to 3.2Gbps) SFP/SFF Modules
Gigabit Ethernet Optical Transmitters
Fibre Channel Optical Transmitters
Infiniband Optical Transmitters
♦ Supports all SFF-8472 Digital Diagnostics
♦ 2mA to 15mA Modulation Current
♦ 1mA to 15mA Bias Current
♦ Optional Peaking Current to Improve VCSEL Edge
♦ Supports Common Cathode and Differential
♦ Automatic Power Control
♦ Safety Circuits Compliant with SFF and SFP
♦ 4mm ✕ 4mm, 24-Pin Thin QFN Package
TEMP RANGE PIN-PACKAGE
-40°C to +85°C 24 Thin QFN-EP*
MAX3740AETG+ -40°C to +85°C 24 Thin QFN-EP*
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
Typical Application Circuit
________________________________________________________________ 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.