4-Channel, LVDS, Dual-Output, Laser Diode Driver with Oscillator

The AD9665 is a laser diode driver for high performance CD-RW and DVD recordable drives. It includes four channels for four different optical power levels: the read channel generates a continuous output power level, whereas Channel 1, Channel 2, and Channel 3 can be used as write channels that can be controlled with an LVDS or TTL interface. The WxDIS and RDIS pins are active low logic. The OSCEN pin is controlled by an active high TTL signal. All active channels are summed at the output where Write Channel 1 can contribute at least 325 mA output current, and Write Channel 2 and Write Channel 3 can contribute at least 250 mA and 150 mA, respectively. The level of the output current is set by an external resistor, which converts this voltage into a current at the WxSET pin.

An on-chip oscillator is provided to allow output current modulation and to reduce laser-mode hopping. Four external resistors permit the setting of two distinct values for the frequency and swing of the oscillator. The oscillator can output up to 100 mA p-p of current (push-pull oscillator) with a frequency range of 200 MHz to 500 MHz.

Applications

* DVD-R, DVD+R, DVD-RW, DVD+RW, DVD-RAM supercombo drives

* Magneto-optical (MO) drives

* Laser diode current switching

* OTDR laser drivers

* Dual, current-controlled output current sources with 4 input channels

* TTL-selectable output

* Stable on-chip oscillators with independent frequency and amplitude control

* TTL- or LVDS-selectable write channel enables negative logic

* Independent TTL oscillator enables positive logic

* 170 mA minimum output current for the read channel