SML2120 Datasheet, PDF (1/32 Pages) Summit Microelectronics, Inc. – Programmable Adaptive Laser Power Controller with Dual Lookup Tables

SML2120
Programmable Adaptive Laser Power Controller with Dual Lookup Tables
Preliminary Information¹ (See Last Page)
–
FEATURES AND APPLICATIONS
–
INTRODUCTION
Features:
• Integrated Automatic Power Control (APC) circuit
• 100 mA bias current sink capability
• Dual low-current outputs (up to 2.5 mA) based on two
independent 256x8 Lookup Table values
• Bias current and/or temperature monitoring capability
• Dual high/low alert registers
• Advanced lookup algorithm eliminates unnecessary
output changes
• Flexible voltage operation;
0 to 5V, 0 to 3.3V, or -5.2V to +3.3V
• I²C 2-wire serial bus interface for programming
configuration, control values, monitoring, and
operational status - 100KHz and 400KHz
• Small 5X5 28-Pin QFN Package
Applications:
• Laser power management for Telecom/Datacom
motherboards
• Direct modulation and electro-absorptive modulation
applications
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SIMPLIFIED APPLICATION DRAWING
The SML2120 is an advanced, programmable laser diode
power controller ideal for optical networking applications.
The integrated automatic power control (APC) circuit adapts
to variations in the laser’s power output as detected by a
photo diode.
The SML2120 drives two low current outputs derived from
values stored in independent 256x8 Lookup Tables. The low
current outputs are suitable for controlling the MODSET
input of typical laser driver IC’s. The input stimulus for each
Lookup Table can be configured as the laser temperature,
the bias current, or an external signal. Characteristics of the
laser’s performance over time and temperature are stored
in the lookup tables, allowing the outputs to adapt to system
conditions and optimize overall performance.
Programming of configuration and control values by the
user are simplified with the I²C interface adapter
(SMX3200) and Windows Programming software available
from Summit Microelectronics.
+3.3V
25 VHI
24 _VDD
15 VDD
ILU0 13
VBRIDGE 12
2 _A1
3 ^A2
4 SDA
5 SCL
6 AM#
7 _ALERT#
THERMISTOR 11
SML2120
BIAS 20
EXT_TEMP 23
ILU1 14
MPD 18
C2 16
C1 17
DATA+
DATA–
Typical
Laser Driver
CAPC
APCSET
BIASMAX
MODSET
OUT+
OUT– ^VDD
C_INT
R_INT
NTC
LD
MPD
Typical Laser
Diode with
Photo Diode
and Thermistor
V_DD (+3.3V)
Figure 1. Typical SML2120 Connections to a Laser Driver and Laser Diode
Note: This is an applications example only. Some pins, components and values are not shown.
© SUMMIT Microelectronics, Inc. 2004 • 1717 Fox Drive • San Jose CA 95131-2312 • Phone [phone] • Fax [phone] • www.summitmicro.com
2066 6.3 1/22/04
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