SUMMIT
MICROELECTRONICS, Inc.
Laser Diode Adaptive Power Controller
SML2108
PRELIMINARY
FEATURES
!
Integrated Bias Current Monitor
"
Monitors & Measures Laser Temperature
Directly
"
Eliminates Need for External Thermistor &
Thermal Coupling Issues
"
Alarm Output on Over-temperature Condition
!
Adaptive Modulation Control (AMC)
"
Adjusts Modulation Current as a Function of
the Laser Temperature
"
8
×
8 Programmable Compensation Table
"
256 Independent Compensation Values
"
Integrated 8-Bit Modulation Control DAC
!
Flexible Biasing Architecture
"
Bias Control and Modulation Control:
0 to 10mA / 0 to 100 mA Source,
0 to 100mA Sink
!
Automatic Power Control (APC) with Integrated
10-Bit Programmable Offset
"
Automatic Initial Bias Optimization
!
Electronic Calibration Through 2-wire Interface
!
3V or 5V Operation
DESCRIPTION
The SML2108 is an adaptive power controller for laser
diodes. It is the industry's first integrated device that can
directly monitor and measure a laser diode's temperature,
and provide a variable modulation current. The
SML2108's integrated active feedback loop is used to
calibrate and control the mean and modulation power of
high speed, high power laser diodes.
Inherent manufacturing tolerances introduce variations of
performance in laser diodes. These variations, combined
with parametric changes over the laser’s extreme tem-
perature range and laser ageing, call for an efficient
temperature compensation scheme. Using an internal
digital control loop and a programmable nonvolatile com-
pensation lookup table, the SML2108 provides the most
optimum adaptive power control with a minimum number
of external components.
The SML2108 removes the need for any manual calibra-
tion of the laser control circuit, which is currently the
industry standard practice. All calibration values are
programmed through the 2-wire communication interface,
which can be controlled by most production ATE equip-
ment.
Programming of configuration, control and calibration
values by the user can be simplified with the interface
adapter and Windows GUI software obtainable from Sum-
mit Microelectronics.
The SML2108 is available in 48 lead TQFP.
SIMPLIFIED APPLICATION DIAGRAM
VDD
LASER
DIODE
IN+
IN–
LASER
MODULATION
DRIVER
MODSET
VDD
VDD
AUTOMON
SDA
Interface
SCL
MODN
IMOD
MONITOR
DIODE
BIASN
DETECT
SML2108
VSS
2053 SAD 1.0
©SUMMIT MICROELECTRONICS, Inc., 2000 • 300 Orchard City Dr., Suite 131 • Campbell, CA 95008 • Phone 408-378-6461 • FAX 408-378-6586 • www.summitmicro.com
Characteristics subject to change without notice
2053 2.2 11/07/00
1
SUMMIT [ SUMMIT MICROELECTRONICS, INC. ]
