3-Channel Laser Driver + Oscillator + APC Amplifier
Features
General Description
• 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
• Fast Settling APC Amplifier
The EL6258C is a high-performance three channel laser diode current
amplifier that provides controlled current to a grounded laser diode.
The three amplifiers can provide up to 150 mA per channel of DC or
pulsed current. Channels 2 and 3 must be used as the write channels,
with switching speeds of approximately one nanosecond rise/fall time.
All three channels 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 voltage 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 current source at pin IOUT.
Applications
•
•
•
•
DVD drives
CD-RW applications
Writable optical drives
Laser diode current switching
Ordering Information
An on-chip 500 MHz oscillator is provided to allow current modulation 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 an ‘L’ signal is applied to the
OUTEN pins. 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 IOUT shut-off is also achieved by
holding the ENABLE pin low, which will override the OUTEN control pins.
The EL6258C also includes a fast settling APC amplifier designed to
interface directly with the power monitor photodiode and the sampleand-hold amplifier, for read and write power control.
Connection Diagram
Part No
Temp. Range
Package
Outline #
EL6258CU
0°C to +70°C
QSOP-24
MDP0040
1
24
2
23
3
22
4
21
5
20
6
19
7
18
8
17
9
16
10
15
11
14
12
13
GND
VCC
VCC
IOUT
IOUT
GND
RAMP
ENABLE
OSCEN
VCC
GND
PDIN
February 22, 2000
GND
IINR
IIN2
GND
RFREQ
IIN3
OUTENR
OUTEN2
OUTEN3
GND
VREF
VOUT
© 1997 Elantec, Inc.
EL6258C - Product Brief
EL6258C - Product Brief
