EL6250C - Product Brief
EL6250C - Product Brief
Split Supply Laser Driver and Oscillator
Features
• Split Supply for Blue Laser diode
capability
• High-performance laser diode
driver
• Voltage-controlled output current
source to 150mA per channel,
requiring one external set resistor
per channel
• Current-controlled output current
source to 150mA per channel
• Rise time = 2.0ns
• Fall time = 2.0ns
• On chip oscillator with frequency
and amplitude control by use of
external resistors to ground
• Oscillator to 500MHz
• Oscillator to 100mA pk/pk
• Single +5V supply (±10%)
• Disable feature for power-up
protection and power savings
• CMOS control signals
General Description
The EL6250C is a split supply, four channel laser diode current ampli-
fier that provides controlled current to a grounded laser diode. Channels
2, 3, and 4 must be used as the write channels, with switching speeds of
approximately two nanoseconds rise/fall time. All four 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 pin I
IN
. The current
seen at this pin is then amplified to become a current source at pin I
OUT
.
An on-chip 500MHz oscillator is provided to allow current modulation
when in the read mode. This is turned on when the EOSC 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).
Output current pulses are enabled when an ‘L’ signal is applied to the
OE pin. No output current flows when OE is ‘H’, and additional laser
diode protection is provided since the OE input will float high when
open. Complete I
OUT
shut-off is also achieved by holding the CE pin
low, which will override the OE control pins. VCC2 should be set to
about 1.5V above the maximum laser voltage, while VCC1 should be set
to +5V to minimize chip dissipation.
The external resistors allow the user to accurately and independently 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 cur-
rent DAC or other current source.
Applications
• Writable optical drives
• Laser diode current switching
• General blue laser usage
Ordering Information
Part No
EL6250CU
Temp. Range
0°C to +70°C
Package
QSOP-24
Outline #
MDP0040
Connection Diagram
1 GND
2 IINR
3 GND
4 IIN2
5 RFREQ
6 IIN3
7 IIN4
8 VCC1
9 OE2
10 OE3
11 OE4
12 GND
GND 24
VCC2 23
VCC2 22
IOUT 21
IOUT 20
GND 19
RAMP 18
CE 17
EOSC 16
VCC2 15
VCC2 14
GND 13
October 25, 2001
Note:
All information contained in this data sheet has been carefully checked and is believed to be accurate as of the date of publication; however, this data sheet cannot be a “controlled document”. Current revisions, if any, to these
specifications are maintained at the factory and are available upon your request. We recommend checking the revision level before finalization of your design documentation.
© 2001 Elantec Semiconductor, Inc.
ELANTEC [ ELANTEC SEMICONDUCTOR ]
