MAX3948 Просмотр технического описания (PDF) - Maxim Integrated
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MAX3948 Datasheet PDF : 37 Pages
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19-5943; Rev 0; 6/11
EVALUATION KIT AVAILABLE
MAX3948
11.3Gbps, Low-Power, DC-Coupled Laser Driver
General Description
The MAX3948 is a 3.3V, multirate, low-power laser diode
driver designed for Ethernet, Fibre Channel, and SONET
transmission systems at data rates up to 11.3Gbps. This
device is optimized to drive a differential transmitter
optical subassembly (TOSA) with a 25I flex circuit. The
unique design of the output stage enables DC-coupling
to unmatched TOSAs, thereby lowering transmitter power
consumption by more than 100mW.
The MAX3948 receives differential AC-coupled signals
with on-chip termination. It can deliver laser modula-
tion currents of up to 85mA at an edge speed of 26ps
(20% to 80%) into a 5I external differential load. The
device is designed to have a high-bandwidth differen-
tial signal path with on-chip back termination resistors
integrated into its outputs. An input equalization block
can be activated to compensate for SFP+/QSFP+ host
connector losses. The integrated DC circuit provides
programmable laser DC currents up to 61mA. Both the
laser DC current generator and the laser modulator can
be disabled from a single pin.
The device offers one dedicated pin (VSEL) to program up
to four channel addresses for multichannel applications.
The use of a 3-wire digital interface reduces the pin count
while permitting adjustment of input equalization, polar-
ity, output deemphasis, and modulation and DC currents
without the need for external components. The MAX3948
is available in a 3mm x 3mm, 16-pin TQFN package, and
is specified for the -40NC to +95NC extended temperature
range.
Applications
40GBASE-LR4 QSFP+ Optical Transceivers
10GBASE-LR SFP+ Optical Transceivers
10GBASE-LRM SFP+ Optical Transceivers
OC192-SR SFP+ SDH/SONET Transceivers
Benefits and Features
S Lowest Power Consumption
168mW Typical IC Power Dissipation at 3.3V
(LDMOD = 40mA, LDDC = 20mA)
383mW Total Transmitter Power Dissipation at
3.3V Including LDMOD = 40mA, LDDC = 20mA
Enables < 1W Maximum Total SFP+ Module
Power Dissipation
Enables < 2.5W Maximum Total QSFP+ Module
Power Dissipation
S Saves Board Space
Small 3mm x 3mm Package
DC-Coupling to the Laser Reduces External
Component Count
S Flexibility
Operate Up to Four MAX3948 ICs Over Single
3-Wire Digital Interface
Programmable Modulation Current Up to
85mA (5ω Load)
Programmable DC Current Up to 61mA
(Translates to Up to 100mA Laser Bias Current)
Programmable Input Equalization and Output
Deemphasis
S Safety
Supports SFF-8431 SFP+ MSA and SFF-8472
Digital Diagnostic
Integrated Eye Safety Features with Maskable
Faults
DC Current Monitor
Ordering Information appears at end of data sheet.
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