T0815

The T0815 is a laser diode driver for the operation of a grounded laser diode for CD-RW drives. T0815 includes three channels for three different optical power levels which arecontrolled by a separate IC. The read channel generates a continuous output levelwhereas the channels 2 and 3 are provided as write channels with very fast switchingspeeds. Write current pulses are enabled when a 'low' signal is applied to the NE pins.

All channels of T0815 are summed together at the IOUT pin. Each channel can contribute up to250 mA to the total output current of up to 300 mA. A total gain of 400 is providedbetween each reference current input and the output. Although the reference inputsare current inputs; voltage control is possible by using external resistors.

An on-chip RF oscillator of T0815 is provided to reduce laser mode hopping noise during readmode. Frequency and swing can be set by two external resistors. Oscillation isenabled by a 'high' at the ENOSC pin. Complete output current and oscillator switch-off is achieved by a 'low' at the ENABLE input.

The T0815 also includes a fast settling APC (Adaptive Power Control) transimpedanceamplifier. It is provided to interface between the front end monitor photo diode and theALPC (Adaptive Laser Diode Power Controller) circuit.