3-Channel Laser Diode Driver
with Oscillator
AD9662
FEATURES
FUNCTIONAL BLOCK DIAGRAM
Current-controlled current source
with 3 input channels
Output current for Channel 3—315 mA
Output current for other channels—210 mA
Rise time/fall time of 0.8 ns
On-chip oscillator
Single 5 V power supply (±10%)
Low output overshoot
Low power consumption
IN3
OUTEN3
CHANNEL 3
IN2
OUTEN2
CHANNEL 2
APPLICATIONS
INR
OUTENR
OUTPUT
IOUT
ENABLE
READ CHANNEL
CD-RW drives
DVD-RW, DVD+RW, MO drives
Laser diode current switching
OSCILLATOR
GENERAL DESCRIPTION
RF
The AD9662 is a laser diode driver for high performance CD
and DVD recordable drives. It includes three channels for three
different optical power levels: the read channel generates a
continuous output power level, whereas Channel 2 and
Channel 3 are used as write channels having 0.8 ns rise/fall
times. All channel currents are summed at the IOUT pin. Each
channel’s output current is established by multiplying the
channel’s gain by the channel’s input current. The input current
for each of the input channels—INR, IN2, and IN3—can be set
either by using an external resistor that converts an input
voltage to a current or by directly using a current source.
RS
04389-0-001
OSCEN
Figure 1. AD9662 3-Channel Laser Diode Driver
An on-chip oscillator is provided to allow output current
modulation (to reduce laser mode hopping). Two external
resistors control the frequency and the amplitude swing of the
oscillator. The push-pull oscillator can swing up to 100 mA p-p
and has a frequency range of 200 MHz to 500 MHz.
Rev. C
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