3-Channel Laser Diode Driver

with Oscillator

AD9662

Rev. C

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FEATURES

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

APPLICATIONS

CD-RW drives

DVD-RW, DVD+RW, MO drives

Laser diode current switching

GENERAL DESCRIPTION

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

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.

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.

FUNCTIONAL BLOCK DIAGRAM

CHANNEL 3

CHANNEL 2

READ CHANNEL

OSCILLATOR

OUTPUT

ENABLE

IN3

OUTEN3

IN2

OUTEN2

INR

OUTENR

OSCEN

Figure 1. AD9662 3-Channel Laser Diode Driver