The SL6025 is a high performance dual four-channel laser driver that provides controlled current to two grounded laser diodes. 

The SEL1 pin selects IOUT1 or IOUT2 pin active to drive either CD or DVD laser diode.

The currents flowing into IR, I2, I3 and I4 determine the level of the output current with gains 100 for read channel IR and 250 for the other channels.

The channel enable  pin at  ERB, or  the  pin pairs  of E2-E2B, E3-E3B, and E4-E4B determine current waveform timing.  The output write current pulses are enabled when a low is applied to ERB or high-low to these pin pairs with switching speed less than 1 ns rise/fall time.

Two on-chip oscillators can provide  up to 600MHz modulation to the output current. Pin OSEN is held high to turn on the oscillators. Each oscillator’s amplitude and frequency is set by an external resistor connected to ground from RA1 or RA2. And frequency is set from RF1 or RF2.

The total output current is the sum of current from the four charnels and the oscillator.

The write channel 2, 3, and 4 enables are LVDS interface. IOUT1or IOUT2 is enabled when SEL1 is high or low respectively. 

There is a whole chip enable pin ENA needed to be high. And complete LD shut-off is achieved by holding ENA low.