Rev. 4522ES–DVD–01/04

Features

× 4 mm) or SSO16 Package

Applications

Description

The T0806 is a laser diode driver for the operation of two different grounded laser

diodes for DVD-RAM (650 nm) and CD-RW (780 nm) drives. It includes three chan-

nels for three different optical power levels which are controlled by a separate IC. The

read channel generates a continuous output level whereas channels 2 and 3 are pro-

vided as write channels with very fast switching speeds. Write 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 channel can contribute up to 250 mA to the total output current of up to

300 mA. A total gain of 100 is provided between each reference current input and the

selected output. Although the reference inputs are current inputs, voltage control is

possible by using external resistors.

An on-chip RF oscillator is provided to reduce laser mode hopping noise during read

mode. Swing can be set independently for the two selectable outputs with two different

resistors. Oscillation is enabled by a high signal at the ENOSC pin. Complete output

current and oscillator switch-off is achieved by a low signal at the ENABLE input.

Figure 1. Block Diagram

Channel 2

I3

NE3

I2

NE2

Read channel

RF oscillator

IR

ENOSC

ENABLE

RSA

IOUTA

IOUTB

RF

RSB

SELA

Channel 3

3-Channel Laser

Driver with

RF Oscillator

and 2 Outputs

T0806

Summary