Features

Applications

1.

Description

The T0800 is a laser diode driver for the operation of two different, grounded laser

diodes for DVD-RAM (650 nm) and CD-RW (780 nm). It includes five channels for five

different optical power levels which are controlled by a separate IC. The read channel

generates a continuous output level. The channels 2 to 5 are provided as write chan-

nels with very fast switching speeds. When a low signal is applied to the NE pins, write

current pulses are enabled. All channels are summed together and switched to one of

the two outputs IOUTA or IOUTB by the select input SELA. Each channel can contrib-

ute up to 200 mA to the total output current of up to 250 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 resis-

tors. An on-chip RF oscillator reduces laser mode hopping noise during read mode.

Frequency and swing can be set independently for the two selectable outputs with two

pairs of 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.

5-Channel Laser

Driver with RF

Oscillator and

2Outputs

T0800

Rev. 4503D–DVD–02/05