Features
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Current-controlled Output Current Source with 4 Input Channels
Low-power Consumption
Output Current up to 150 mA, Read Channel and Channel 2
Output Current up to 200 mA, Channel 3 and Channel 4
Total Output Current to 300 mA
Rise Time 1.0 ns, Fall Time 1.1 ns
On-chip RF Oscillator
Control Frequency and Swings by Use of 2 External Resistors
Oscillator Frequency Range from 200 MHz to 600 MHz
Oscillator Swing to 100 mA
Single 5 V Power Supply
Common Enable/Disable Input
TTL/CMOS Control Signals
Small SSO16 Package
4-channel Laser
Driver with RF
Oscillator
T0820
Application
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DVD-RAM
DVD-RW
DVD+RW
CD-RW
Writable Optical Drives
Description
The T0820 is a laser diode driver for the operation of a grounded laser diode for
writable optical drives. It includes four channels for four different optical power levels
which are controlled by a separate IC. The read channel generates a continuous
output level whereas channels 2 to 4 are provided as write channels with very fast
switching speeds. Write current pulses are enabled when a "low" signal is applied to
the NE pins. All channels are summed together at the IOUT pin. Read channel and
channel 2 can contribute up to 150 mA and channels 3 and 4 up to 200 mA to the total
output current of up to 300 mA. A total gain of 100 is 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. Frequency and swing can be set
by two external resistors. Oscillation is enabled by a "high" at the ENOSC pin. Com-
plete output current and oscillator switch-off is achieved by a `low' at the ENABLE
input.
Figure 1.
Block Diagram
I4
NE4
Channel 4
I3
NE3
I2
NE2
IR
ENABLE
Channel 3
Channel 2
IOUT
Read channel
ENOSC
RF oscillator
RF
RS
Rev. 4506F–DVD–09/04
ATMEL [ ATMEL CORPORATION ]
