EL6252/6252C pdf datasheet (2-

The EL6252C is a high-performance two channel laser diode current
amplifier that provides controlled current to a grounded laser diode.
The write amplifier can provide over 200mA of DC or pulsed current.
The R and W channels have switching speeds of approximately one
nanosecond rise/fall time and are summed together at the IOUT output.
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 by
100X to become a current source at pin IOUT.
An on-chip 500 MHz oscillator is provided to allow current modulation
when in the read mode. This is turned on when the OSCEN pin is
held high (floating not recommended). Complete control of amplitude
and frequency is set by two external resistors connected to ground at
pins RFREQ and RAMP (see graphs in this data sheet for further
explanation).
Write current pulses appear when an ‘L’ signal is applied to the OUTENW pin.