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.
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General Description
The EL6257C is a high-performance four channel laser diode current
amplifier that provides controlled current to a grounded laser diode.
The four amplifiers can provide up to 150 mA per channel of DC or
pulsed current. Channels 2, 3, and 4 must be used as the write chan-
nels, with switching speeds of approximately one nanosecond rise/fall
time. All four channels are summed together at the I
OUT
output, allow-
ing the user to create multilevel 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 (virtually 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 any of the
OUTEN pins for channels 2, 3, and 4 (the write channels) are low (see
truth table).
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
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 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
1
2
3
4
16
15
14
13
5
6
7
12
11
9
8
10
20
19
18
17
24
23
22
21
I
INR
GND
V
CC
V
CC
I
OUT
RAMP
ENABLE
OSCEN
I
IN2
RFREQ
I
IN3
I
IN4
OUTEN
OUTEN2
OUTEN3
OUTEN4
GND
I
OUT
GND
V
CC
V
CC
GND
GND
GND
Features
High-performance laser diode
driver
Voltage-controlled output current
source to 150 mA per channel,
requiring one external set resistor
per channel
Current-controlled output current
source to 150 mA per channel
Rise time = 1.0 ns
Fall time = 1.1 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
TTL/CMOS control signals
Applications
DVD drives
CD-RW applications
Writable optical drives
Laser diode current switching
Ordering Information
Part No
Temp. Range
Package
Outline #
EL6257CU
0C to +70C
QSOP-24
MDP0040
EL6257C - Product Brief
4-Channel Laser Diode Driver + Oscillator
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EL6257C - Product Brief
4-Channel Laser Diode Driver + Oscillator
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General Disclaimer
Specifications contained in this data sheet are in effect as of the publication date shown. Elantec, Inc. reserves the right to make changes in the cir-
cuitry or specifications contained herein at any time without notice. Elantec, Inc. assumes no responsibility for the use of any circuits described
herein and makes no representations that they are free from patent infringement.
WARNING - Life Support Policy
Elantec, Inc. products are not authorized for and should not be used
within Life Support Systems without the specific written consent of
Elantec, Inc. Life Support systems are equipment intended to sup-
port or sustain life and whose failure to perform when properly used
in accordance with instructions provided can be reasonably
expected to result in significant personal injury or death. Users con-
templating application of Elantec, Inc. Products in Life Support
Systems are requested to contact Elantec, Inc. factory headquarters
to establish suitable terms & conditions for these applications. Elan-
tec, Inc.'s warranty is limited to replacement of defective
components and does not cover injury to persons or property or
other consequential damages.
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Printed in U.S.A.
Elantec Semiconductor, Inc.
675 Trade Zone Blvd.
Milpitas, CA 95035
Telephone: (408) 945-1323
(888) ELANTEC
Fax:
(408) 945-9305
European Office: +44-118-977-6020
Japan Technical Center: +81-45-682-5820
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