EL6279C Datasheet, PDF (1/2 Pages) Elantec Semiconductor – 4-Ch Laser Diode Driver Oscillator

EL6279C - Product Brief
4-Ch Laser Diode Driver + Oscillator
Features
• Ultra-Small Package Outline
• Current-controlled output current
source to 100 mA per channel,
requiring one external set resistor
per channel
• Auto Oscillator On-Off with
OUTEN Signals
• Rise time = 3.0 ns
• Fall time = 3.5 ns
• On chip oscillator with frequency
and amplitude control by use of
external resistors to ground
• Oscillator to 500 MHz
• Oscillator to 100 mA pk/pk
• Single +5V supply (±10%)
• Current amplification = 100
• Disable feature for power-up
protection and power savings
• CMOS control signals
Applications
• CD-RW applications
• Writable optical drives
• Laser diode current switching
Ordering Information
Part No.
EL6279CU
Temp. Range
0°C to +70°C
Package
QSOP-16
Outline #
MDP0040
General Description
The EL6279C is a four channel laser diode current amplifier that pro-
vides controlled current to a grounded laser diode. The four amplifiers
can provide up to 100 mA per channel of DC or pulsed current. Chan-
nels 2, 3, and 4 should be used as the write channels, with switching
speeds of approximately three nanosecond rise/fall time. All four
channels are summed together at the I_OUT output, allowing the user to
create multilevel waveforms in order to optimize laser diode perfor-
mance. 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 I_IN pin (virtually ground). The current seen at this pin is then
amplified by 100X to become a current source at pin I_OUT.
Output current pulses are enabled when an ‘L’ signal is applied to the
OUTEN pin. No output current flows when OUTEN is ‘H’, and addi-
tional laser diode protection is provided since the OUTEN input will
float high when open. Complete I_OUT shutoff is also achieved by hold-
ing the ENABLE pin low, which will override the OUTEN control
pins.
An on-chip 500 MHz oscillator is provided to allow output current
modulation when in read mode. The oscillator is enabled when the
OSCEN pin is held high. If any of channels 2, 3, or 4 are active, the
oscillator is switched off. Complete control of amplitude and fre-
quency is set by two external resistors connected to ground at pins
RFREQ and RAMP (see graphs in this data sheet for further
explanation).
The external I_IN resistors allow the user to accurately and indepen-
dently set each amplifier transconductance by applying a voltage to
each resistor, without restriction on the voltage range, thus ensuring
broad voltage DAC compatibility. Alternatively, the I_IN pin can be
biased from a current DAC or other current source.
Connection Diagram
IINR 1
IIN2 ²
RFREQ 3
IIN3 4
IIN4 5
OUTEN2 6
OUTEN3 7
OUTEN4 8
16 VCC
15 _VCC
14 _IOUT
13 GND
12 RAMP
11 _ENABLE
10 OSCEN
9 VCC
© 1998 Élantec, Inc.