MAX3646 Datasheet, PDF (1/14 Pages) Maxim Integrated Products – 155Mbps to 622Mbps SFF/SFP Laser Driver with Extinction Ratio Control

19-3161; Rev 1; 7/04
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155Mbps to 622Mbps SFF/SFP
Laser Driver with Extinction Ratio Control
General Description
The MAX3646 is a +3.3V laser driver designed for mul-
tirate transceiver modules with data rates from
155Mbps to 622Mbps. Lasers can be DC-coupled to
the MAX3646 for reduced component count and ease
of multirate operation.
Laser extinction ratio control (ERC) combines the features
of automatic power control (APC), modulation compensa-
tion, and built-in thermal compensation. The APC loop
maintains constant average optical power. Modulation
compensation increases the modulation current in pro-
portion to the bias current. These control loops, com-
bined with thermal compensation, maintain a constant
optical extinction ratio over temperature and lifetime.
The MAX3646 accepts differential data input signals.
The wide 5mA to 60mA (up to 85mA AC-coupled) mod-
ulation current range and up to 100mA bias current
range, make the MAX3646 ideal for driving FP/DFB
lasers in fiber optic modules. External resistors set the
required laser current levels. The MAX3646 provides
transmit disable control (TX_DISABLE), single-point
fault tolerance, bias-current monitoring, and photocur-
rent monitoring. The device also offers a latched failure
output (TX_FAULT) to indicate faults, such as when the
APC loop is no longer able to maintain the average
optical power at the required level. The MAX3646 is
compliant with the SFF-8472 transmitter diagnostic and
SFP MSA timing requirements.
The MAX3646 is offered in a 4mm x 4mm, 24-pin thin
QFN package and operates over the extended -40°C to
+85°C temperature range.
Features
♦ Single +3.3V Power Supply
♦ 47mA Power-Supply Current
♦ 85mA Modulation Current
♦ 100mA Bias Current
♦ Automatic Power Control (APC)
♦ Modulation Compensation
♦ On-Chip Temperature Compensation
♦ Self-Biased Inputs for AC-Coupling
♦ Ground-Referenced Current Monitors
♦ Laser Shutdown and Alarm Outputs
♦ Enable Control and Laser Safety Feature
Ordering Information
PART
TEMP
RANGE
MAX3646ETG -40°C to +85°C
MAX3646ETG+ -40°C to +85°C
+Denotes lead-free package.
PIN-
PACKAGE
24 Thin QFN
24 Thin QFN
PKG
CODE
T2444-1
T2444-1
Pin Configuration
TOP VIEW
Applications
Multirate OC-3 to OC-12 FEC Transceivers
125Mbps Ethernet SFP, GBIC, and 1 x 9
Transceivers
24 23 22 21 20 19
MODTCOMP 1
18 MD
V_CC 2
17 VCC
IN+ 3
IN- 4
MAX3646
16 OUT+
15 OUT-
V_CC 5
14 VCC
TX_DISABLE 6
13 BIAS
7 8 9 10 11 12
Typical Application Circuit appears at end of data sheet.
THE EXPOSED PADDLE MUST BE SOLDERED TO SUPPLY
GROUND ON THE CIRCUIT BOARD.
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.