I7032 Datasheet, PDF (7/14 Pages) List of Unclassifed Manufacturers – 200 Mbps Laser-Diode Driver

i7032
5. Product description
The i7032 consists of a laser bias generator
with automatic power control (APC), a
modulation current driver, and a reference
generator with temperature compensation.
5.1. Modulation circuitry
The modulator output stage is designed to
drive up to 80mA into 25Ω load in either AC-
couple or DC-coupled mode. The amplitude of
the modulation current is set with a resistor at
IMODSET pin or with resistors at IMODSET and
IMODTC pins. Please refer to 4.3. Typical
operating characteristics figure 5 and figure 7 for
more information.
The input swing is required to completely
switch the output stage depends on both R_OASDJ
and modulation current.
5.2. Automatic power control
The amplitude of DC current to the laser
diode is determined by setting the resistor at
IBIASSET pin (Please refer to 4.3. Typical
operating characteristics figure 4). To maintain
constant average optical power, i7032
incorporates a control loop to compensate for
change in laser threshold current over
temperature and lifetime.
A monitor photodiode mounted in the laser
package is used to convert the optical power into
a monitor current. This current flow into the IPIN
input. The IPINSET current mirror draws current
away from IPIN node. When the current into IPIN
node equals the current drawn away by IPINSET,
the node voltage is set by 4/7xVcc reference.
When the monitor current exceeds IPINSET, the
IPIN node voltage will be forced higher. If the
monitor current decreases, the IPIN node voltage
is decreased. In either case the voltage change
results in a feedback current at IBIASFB node.
5.3. APC failure Indicator
The i7032 provides an APC failure indicator
to indicate an APC loop tacking failure. FAILOUT
is set low when the APC loop can no longer
adjust the bias current to maintain the desired
monitor current. This output is pulled up to Vcc
through an external 2.7KΩ resistor.
5.4. Enable inputs
The i7032 provides complementary enable
inputs (ENB+, ENB-). The laser is disabled by
reducing the reference voltage outputs (VREF1,
VREF2). Both ENB+ and ENB- pins can not be
floating and only one logic state enables laser
operation (please refer to Table 1).
ENB-
ENB+
VREF
0
0
Off
0
1
On
1
0
Off
1
1
Off
Table 1. i7032 truth table
© 2003 iCreate Technologies Corporation
This document contains preliminary information on product but not yet fully characterized.
iCreate Technologies Corporation reserves the right to change the specification in any manner without notice.
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ICR-DS-i7032001