Dual current-controlled output current sources
Stable on-chip oscillators with independent frequency
TTL- or LVDS-selectable write channel enables
TTL- or LVDS-selectable oscillator enable
150 mA minimum output current for Read Channel
275 mA minimum output current for Write Channel 1
170 mA minimum output current for Write Channel 2
150 mA minimum output current for Write Channel 3
Rise time/fall time of ≤0.8 ns
Low output overshoot
Low power consumption
Single 5 V power supply (±10%)
DVD-R, DVD+R, DVD-RW, DVD+RW, DVD-RAM
Laser diode current switching
The AD9668 is a laser diode driver for high performance
CD-RW and DVD recordable drives. It includes four channels
for four different optical power levels; the Read Channel
generates a continuous output power level, whereas Channel 1,
Channel 2, and Channel 3 can be used as write channels that
can be controlled with either an LVDS or a TTL interface. The
OSCEN pin is also controlled by either an LVDS or a TTL
signal. All channels are summed at the selected LD output pin,
where Write Channel 1 can contribute at least 275 mA output
current, and Write Channel 2 and Write Channel 3 can contribute
at least 170 mA and 150 mA, respectively. The level of the output
current is set by an external resistor that converts an input voltage
into a current at the xSET pins.
An on-chip oscillator is provided to allow output current
modulation and to reduce laser mode hopping. Four external
resistors permit the setting of two different values for both
oscillator frequency and amplitude, one for each output. The
oscillator can output up to 100 mA p-p of current (push-pull
oscillator) with a frequency range of 200 MHz to 500 MHz.
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.
with 4 input channels
and amplitude control
Laser Diode Driver with Oscillator
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
For more information about the AD9668, contact
Analog Devices, Inc. at email@example.com.
4-Channel LVDS, Dual-Output,
Figure 2. 4-Channel, LVDS, Laser-Driver Pin Configuration
FADJ1 FADJ2 AADJ1 AADJ2
Figure 1. 4-Channel LVDS Laser Driver Block Diagram
FUNCTIONAL BLOCK DIAGRAM
© 2005 Analog Devices, Inc. All rights reserved.
(Not to Scale)