ATR0839 Datasheet, PDF (1/6 Pages) ATMEL Corporation – 4-Channel LVDS Laser Driver for Dual-layer Application

Features
• Current-controlled Output Current Source with 4 Input Channels
• LVDS Compatible Inputs at Channels 2, 3 and 4 with On-chip 100Ω Termination
• Separate Read-channel Enable
• Two Selectable Outputs for Grounded Laser Diodes
• Output Current per Channel up to 350 mA
• Total Output Current up to 600 mA
• On-chip RF Oscillator with LVDS Enable
• 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 5V Power Supply
• Small Pb-free QFN24, 4 mm × 4 mm Package
Applications
• Double Layer DVD+/-RW with CD-RW Capability
• Recordable Optical Drives
4-Channel LVDS
Laser Driver for
Dual-layer
Application
ATR0839
1. Description
The ATR0839 is a laser diode driver designed to operate two different grounded laser
diodes for DVD-RW/DVD+RW (650 nm) and CD-RW (780 nm). The device includes
four channels for four different optical power levels. The write channels (channels 2
to 4) can be controlled by fast LVDS (Low Voltage Differential Signaling).
The read channel generates a continuous output current, whereas 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 (channel 2 to 4) can contribute up to 350 mA
to the total output current of up to 600 mA. The read channel can contribute up to
150 mA. Total gains of 100 (read channel) and 250 (channels 2, 3 and 4), are pro-
vided between each reference current input and the selected output. Although the
reference inputs are current inputs, voltage control is possible by using external resis-
tors. 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 can be enabled either by
LVDS signaling at ENOSC/NENOSC pins, or by a high at ENOSC pin in single-ended
mode. Complete shutdown of the output currents is achieved by a low signal at the
ENABLE input.
In read mode, the reference currents (I2, I3, I4) should be switched off to reduce
power consumption.
In case of uncertain (balanced) enable signals, a built-in fail-safe circuit will reduce the
laser diode output current to a safe value.
Summary
Rev. 4852BS–DVD–09/05
Note: This is a summary document. A complete dorcument
is available under NDA. For more information, please con-
tact your local Atmel sales office.