The EL6838 is a high performance,
dual output, laser driver for writeable
‘super-combo’ CD - DVD drives. The
ENA pin enables the chip, while the SEL1 pin selects the
IOUT pin. Various waveforms can be generated where the
amplitude is determined by the currents flowing into IINR,
IIN2, IIN3, and IIN4. The timing is determined by the signals
at OUTEN2, OUTEN3, and OUTEN4. The oscillator is
enabled when OSCEN is high. The amplified IINR current of
the selected channel is enabled when the ENA pin is high.
The total output current is the sum of the read current, the
enabled write currents, and the oscillator current when
enabled.
Usually a voltage DAC will drive a resistor that is in series
with the IINR, IIN2, IIN3, and IIN4 input. The resistor allows
the user to optimize the current gain for each channel.
Output write current pulses are enabled when a low is
applied to the OUTEN2, OUTEN3, or OUTEN4 pin. The
write current will flow to the selected output. When SEL1 is
high IOUT1 is selected. OUTENR enables read and oscillator
current.
The RF oscillators frequency is determined by RFREQ1 or
RFREQ2, and its amplitude by RAMP1 or RAMP2.