The EL6119 is a dual four-channel laser diode current amplifier that provides controlled current to both a CD and DVD laser diode. Channels 2, 3, and 4 should be used as the write channels, with switching speeds of approximately one nanosecond rise/fall time. All four channels are summed together at the IOUT output, allowing the user to create multilevel waveforms in order to optimize laser diode performance. The level of the output current is set by an analog voltage applied to an external resistor which converts the voltage into a current at the IIN pin (virtually ground). The current seen at this pin is then amplified to become a current source at pin IOUT.