3UHOLPLQDU\
3UHOLPLQDU\
CS6709
200Mbps Fiber-Optic Laser Diode Driver
USA:
4020 Moorpark Avenue Suite 115
San Jose, CA, 95117
Tel: 408-243-8388 Fax: 408-243-3188
Sales@myson.com.tw
www.myson.com.tw
Rev.0.91 November 2002
page 1 of 17
Myson Century, Inc.
Taiwan:
No. 2, Industry East Rd. III,
Science-Based Industrial Park, Hsin-Chu, Taiwan
Tel: 886-3-5784866 Fax: 886-3-5784349
BLOCK DIAGRAM
GENERAL DESCRIPTION
FEATURES
APPLICATIONS
Rise/fall time < 1ns.
Maximum programmable 80mA modulation
current.
Maximum programmable 100mA bias current.
Maximum 2V laser diode forward voltage.
Differential PECL inputs.
Modulation current compensation to track the
temperature dependence of the laser diode output
power level.
Automatic Power Control circuitry.
Operation Temperature Range: -40
C~+85
C
Supports both 3.3V and 5V operation.
24-pin SSOP, 32-pin QFN packages and die
available.
The CS6709 is a high-speed fiber optic laser diode
driver suited for applications up to 200Mbps. The
CS6709 accepts differential PECL inputs,
additionally a TTL/CMOS enable pin is provided for
the bias and the modulation current control. If the
enable pin is logic low, both the bias and the
modulation current is set to zero. The bias and the
modulation current of the CS6709 can be set
independently via two external resistors, and the rise/
fall time can be adjusted in a similar way.
An automatic power control (APC) circuit is
provided to ensure constant average power in the
laser diode using a monitor photodiode. A
temperature compensation resistor can be adjusted
to compensate the modulation current with the
temperature variation. A slow-start circuit is provided
to prevent the laser diode from damage. The slow-
start time constant can be programed by adding an
external capacitor.
Normally, the CS6709 is direct coupled to PECL
inputs. However if AC coupled inputs are desired, a
2/3V
DD
input bias point is recommended for 3.3V/5V
supply applications. The output load can be DC
coupled or AC coupled in 5V supply applications, but
AC coupled is only recommended in 3.3V
applications.
155 Mbps ATM
155 Mbps SDH/SONET
Laser Diode Driver Transmitters
DINN
DINP
PREDRIVER
MODP
DCB
MODN
ROFS
RMOD
RDCB
CURRENT
MODULATION SET
BIAS SET
OUTPUT DRIVER
ENBP
FAIL
RISE/FALL TIME SET
AUTO POWER SET
DELAY
START
BANDGAP
AMPLIFIER
CONTROL LOGIC
DC BIAS
DRIVER
BASFB
RPIN
START
PIN
CS6709
TEMPERATURE
COMPENSATION SET
MODCM
BIAS SET
FAIL
0.42xVDD
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