Rev. 4792BS–DVD–05/04

Features

Applications

Description

ATR0809 is a laser diode driver for the operation of two different grounded laser

diodes for DVD-RW/+RW (650 nm) and CD-RW (780 nm). It includes four channels for

four different optical power levels. All channels (channel 1 = read channel, channel 2,

3, 4 = write channels) can be controlled by fast switches. The current pulses are

enabled when a low signal is applied to the NE pins. All channels are summed

together and switched to one of the two outputs IOUTA or IOUTB by the select input

SELA. Each write channel (channel 2, 3 and 4) can contribute up to 350 mA to the

total output current of up to 500 mA. The read channel can contribute up to 150 mA.

Total gains of 100 (read channel), 250 (channel 2 and 3) and 100 (channel 4) are pro-

vided between each reference current input and the selected output. Although the

reference inputs are current inputs, voltage control is also possible by using external

resistors.

An on-chip RF oscillator can be used to reduce laser mode hopping noise in

read mode. The oscillator current amplitude and frequency can be set independently

for the two selectable outputs with four different resistors. Oscillation is enabled by a

high signal at the ENOSC pin. Complete shutdown of the output currents is achieved

by a low signal at the ENABLE input.

Four Channel

Laser Driver

with RF

Oscillator and

Two Outputs

ATR0809

Summary