4 CHANNEL LASER DRIVER - ATMEL Corporation
Description
Features
• 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 www.
DataSheet4U.
com • Small SSO16 Package
4-Channel Laser Driver with RF Oscillator T0820
Application
• • • • •
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.
Complete 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.
4506E–DVD–09/02
1
Pin Configuration
Figure 2.
Pinning SSO16
IR I2 RF
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1 2 3 4
16 15 14 13
VCC1 VCC...
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