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Characteristics subject to change without notice

2053 2.2 11/07/00

SML2108

SUMMIT

MICROELECTRONICS, Inc.

©SUMMIT MICROELECTRONICS, Inc., 2000 • 300 Orchard City Dr., Suite 131 • Campbell, CA 95008 • Phone 408-378-6461 • FAX 408-378-6586 • www.summitmicro.com

PRELIMINARY

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! Integrated Bias Current Monitor

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" Monitors & Measures Laser Temperature

Directly

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" Eliminates Need for External Thermistor &

Thermal Coupling Issues

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" Alarm Output on Over-temperature Condition

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! Adaptive Modulation Control (AMC)

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" Adjusts Modulation Current as a Function of

the Laser Temperature

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" 8

××××× 8 Programmable Compensation Table

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" 256 Independent Compensation Values

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" Integrated 8-Bit Modulation Control DAC

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! Flexible Biasing Architecture

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" Bias Control and Modulation Control:

0 to 10mA / 0 to 100 mA Source,

0 to 100mA Sink

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! Automatic Power Control (APC) with Integrated

10-Bit Programmable Offset

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" Automatic Initial Bias Optimization

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! Electronic Calibration Through 2-wire Interface

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! 3V or 5V Operation

Laser Diode Adaptive Power Controller

SIMPLIFIED APPLICATION DIAGRAM

FEATURES

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.

DESCRIPTION

DETECT

SDA

SCL

BIASN

MODN

AUTOMON

VSS

LASER

MODULATION

DRIVER

VDD

2053 SAD 1.0

MODSET

IN+

IMOD

SML2108

LASER

DIODE

MONITOR

DIODE

Interface

VDD

VDD

IN–