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.

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

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

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

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

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

GND

RAMP

ENABLE

OSCEN

RFREQ

OUTEN

OUTEN2

OUTEN3

OUTEN4

GND

GND

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

0°C to +70°C

QSOP-24

MDP0040

EL6257C - Product Brief

4-Channel Laser Diode Driver + Oscillator