SP8107

The SP8107 is a three channel laser diode driver specifically designed for high speed DVD-RW or DVDRAM applications. SP8107 operates two grounded laser diodes (650nm for DVD and 780nm for CD) and features three input channels that allow setting of three different optical power levels. The first channel (IR) has lower gain (100mA/mA) and output current (up to 200mA) and is used as a read channel. The second (I2) and third (I3) channels have higher gain (250mA/mA) and output current (up to 250mA) and are used as write channels. Each write channel may be switched on/off at very fast switching speeds with TTL/CMOS logic level signals applied to EN2 and EN3 inputs - channels are enabled at low logic level and disabled at high logic level. Outputs of all channels are summed together and connected to one of the outputs IOUT A or IOUT B depending on logic signal at the input SELA. High logic level at SELA selects output I_OUT A, while low logic level selects output I_OUT B. Inputs IR, I2, and I3 are current-controlled with 200 ohm DC impedance but allow voltage control by using external limiting resistors.

An on-chip oscillator SP8107 is used to reduce laser mode hopping in read mode. The frequency of this oscillator may be changed by an external resistor connected to the RF pin. Oscillator swing can be set separately for I_OUT A and I_OUT B outputs by two resistors connected to RSA and RSB pins respectively. The oscillator is enabled by high logic level at the OSCEN pin.

Low logic level at the ENABLE pin disables the entire device. Supply current in disabled mode is below 100uA. Pins EN2 and EN3 have internal pull-up resistors. Pins ENABLE, OSCEN, and SELA have internal pull-down resistors.