T0806

The T0806 is a laser diode driver for the operation of two different grounded laserdiodes for DVD-RAM (650 nm) and CD-RW (780 nm) drives. T0806 includes three chan-nels for three different optical power levels which are controlled by a separate IC. Theread 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 areenabled when a low signal is applied to the NE pins. All channels of T0806 are summedtogether and switched to one of the two outputs IOUTA or IOUTB by the select inputSELA. Each channel can contribute up to 250 mA to the total output current of up to300 mA. A total gain of 100 is provided between each reference current input and theselected output. Although the reference inputs are current inputs, voltage control ispossible by using external resistors.

An on-chip RF oscillator T0806 is provided to reduce laser mode hopping noise during readmode. Swing can be set independently for the two selectable outputs with two differentresistors. Oscillation is enabled by a high signal at the ENOSC pin. Complete outputcurrent and oscillator switch-off is achieved by a 'low' signal at the ENABLE input.