EL6258C - Product Brief
3-Channel Laser Driver + Oscillator + APC Amplifier
Features
General Description
• High-performance laser diode
driver
• Voltage-controlled output current
source requiring one external set
resistor per channel
• Current-controlled output current
source
• Rise time = 1.0ns
• Fall time = 1.1ns
The EL6258C is a high-performance three channel laser diode current
amplifier that provides controlled current to a grounded laser diode.
Channels 2 and 3 must be used as the write channels, with switching
speeds of approximately one nanosecond rise/fall time. All three chan-
nels are summed together at the IOUT output, allowing the user to
create multilevel waveforms. Each level of output current is set by an
analog voltage applied to an external resistor which converts the volt-
age into a current at the IIN pins (virtually ground). The current seen at
these pins is then amplified by 100X (150X on CH3) to become a cur-
rent source at pin IOUT
.
• On chip oscillator with frequency
and amplitude control by use of
external resistors to ground
An on-chip 500MHz 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 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).
• Oscillator to 500MHz
• Oscillator to 100mA pk/pk
• Single +5V supply (±10%)
• Current amplification = 100
• Disable feature for power-up
protection and power savings
Output current pulses are enabled when an ‘L’ signal is applied to the
OUTEN pins. 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 IOUT shut-off is also achieved by
holding the ENABLE pin low, which will override the OUTEN con-
trol pins.
• TTL/CMOS control signals
• Fast settling APC amplifier
Applications
• DVD drives
• CD-RW applications
• Writable optical drives
• Laser diode current switching
The EL6258C also includes a fast settling APC amplifier designed to
interface directly with the power monitor photodiode and the sample-
and-hold amplifier, for read and write power control.
Connection Diagram
GND 1
IINR 2
24 GND
23 VCC
Ordering Information
Part No
Temp. Range
Package
Outline #
EL6258CU
0°C to +70°C
QSOP-24
MDP0040
IIN2
3
22 VCC
GND 4
21 IOUT
20 IOUT
19 GND
18 RAMP
17 ENABLE
16 OSCEN
15 VCC
RFREQ 5
IIN3
6
OUTENR 7
OUTEN2
OUTEN3
8
9
GND 10
VREF 11
VOUT 12
14 GND
13 PDIN
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.