EL6277C Datasheet, PDF (1/2 Pages) Elantec Semiconductor – 3-Channel Laser Diode Driver Oscillator

EL6277C - Product Brief
3-Channel Laser Diode Driver + Oscillator
Features
• Ultra-Small Package Outline
• High-performance laser diode
driver
• Current-controlled output current
source, 100 mA channel R and 2,
200mA channel 3, requiring one
external set resistor per channel
• Rise time = 3.0 ns
• Fall time = 3.5ns
• 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
• TTL/CMOS control signals
Application
• CD-RW applications
• Writable optical drives
• Laser diode current switching
Ordering Information
Part No
EL6277CU
Temp. Range
0°C to +70°C
Package
QSOP-16
Outline #
MDP0041
General Description
The EL6277C is a high-performance three channel laser diode current
driver that provides controlled current to a grounded laser diode.
Channel R and 2 can provide 100mA per channel of DC or pulsed cur-
rent, while channel 3 can provide 200mA per channel. Channels 2, and
3 must be used as the write channels, with switching speeds of approx-
imately three nanosecond rise/fall time. All three channels are
summed together at the I_OUT output, allowing the user to create multi-
level 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 I_IN pin
(near ground). The current seen at this pin is then amplified by 100X
to become a current source at pin I_OUT.
An on-chip 500 MHz oscillator is provided to allow current modula-
tion 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). The oscillator will also turn off whenever either of the
OUTEN pins for channels 2 or 3(the write channels) are low (see truth
table).
Output current pulses are enabled when a ‘Low’ signal is applied to
the OUTEN pin. No output current flows when OUTEN is ‘H’, and
additional laser diode protection is provided since the OUTEN input
will float high when open. Complete I_OUT shut-off is also achieved by
holding the ENABLE pin low, which will override the OUTEN con-
trol pins.
The external resistors allow the user to accurately and independently
set each amplifier trans conductance by applying a voltage to each
resistor, without restriction on the voltage range. Alternatively, the I_IN
pin can be biased from a current DAC or other current source.
Connection Diagram
IINR 1
IIN2 ²
GND 3
RFREQ 4
IIN3 5
OUTENR 6
OUTEN2 7
OUTEN3 8
16 V_CC
15 V_CC
14 I_OUT
13 GND
12 RAMP
11 ENABLE
10 OSCEN
9 V_CC
© 1997 Elantec, Inc.