T0800

The T0800 is a laser diode driver for the operation of two different, grounded laserdiodes for DVD-RAM (650 nm) and CD-RW (780 nm). T0800 includes five channels for fivedifferent optical power levels which are controlled by a separate IC. The read channelgenerates 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 toone of the two outputs IOUTA or IOUTB by the select input SELA. Each channel cancontribute up to 200 mA to the total output current of up to 250 mA. A total gain of 100is provided between each reference current input and the selected output. Althoughthe reference inputs of T0800 are current inputs, voltage control is possible by using externalresistors. An on-chip RF oscillator reduces laser mode hopping noise during readmode. Frequency and swing can be set independently for the two selectable outputswith two pairs of resistors. Oscillation of T0800 is enabled by a 'high' signal at the ENOSC pin.Complete output current and oscillator switch-off is achieved by a 'low' signal at theENABLE input.