ATR0841 Datasheet, PDF (1/6 Pages) ATMEL Corporation – 4-channel Laser Driver with 2 Outputs, 3 LVDS Inputs and Internal Termination

Features
• Current-controlled Output Current Source with 4 Input Channels
• LVDS Compatible Inputs, Channel 2, 3, and 4, with On-chip 100 Ω Termination
• Two Selectable Outputs for Grounded Laser Diodes
• Output Current per Channel up to 350 mA
• Total Output Current up to 500 mA
• On-chip RF Oscillator
• Control of 2 Different Swings and Frequencies by Use of 4 External Resistors
• Oscillator Frequency Range from 200 MHz to 500 MHz
• Maximum Oscillator Current Amplitude 100 mApp
• Single 5 V Power Supply
• Small Pb-free QFN24 4 mm × 4 mm Package
Applications
• DVD Blue Laser
• DVD-RAM/DVD-RW/DVD+RW with CD-RW Capability
• Recordable Optical Drives
Description
The ATR0841 is a laser diode driver designed to operate two differently grounded
laser diodes for DVD-RW/+RW (650 nm) and CD-RW (780 nm). The device includes
four channels for four different optical power levels. The write channels (channel 2 to
4) can be controlled by fast LVDS (Low Voltage Differential Signaling). Due to the inte-
grated termination external resistors are not needed.
The function of the read channel is to generate a continuous output current, channels
2 to 4 are designed as write channels with very fast switching speed. All channels are
summed together and routed to one of the two outputs, IOUTA or IOUTB, controlled
by the select input SELA. Each write channel (channels 2 to 4) can contribute up to
350 mA to the total output current of up to 500 mA. The read channel can contribute
up to 150 mA. Total gain of 100 (read channel) and 250 (channel 2, 3 and 4), respec-
tively, are provided between each reference current input and the selected output.
Although the reference inputs are current inputs, voltage control is possible by using
external resistors. An on-chip RF oscillator is available to reduce laser-mode hopping
noise during read mode. The oscillator current amplitude can be set independently for
the two selectable outputs with two different resistors. Oscillation is enabled by a high
signal at the ENOSC pin. Complete shut down of the output currents is achieved by a
low signal at the ENABLE input.
In case of uncertain (balanced) enable signals, a built-in protection circuit keeps the
laser diode output current within the defined range.
4-channel Laser
Driver with
2 Outputs,
3 LVDS Inputs
and Internal
Termination
ATR0841
Summary
Rev. 4818AS–DVD–09/04