Rev. 4818AS–DVD–09/04
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
2 ATR0841
4818AS–DVD–09/04
Figure 1. Block Diagram
Channel 3
Channel 2
Channel 1
Read Channel
RF oscillator
Channel 4
I4
E4
NE4
I3
E3
NE3
I2
E2
NE2
IR
ENABLE
RFA RFB RSA RSB SELA
IOUTA
IOUTB
ENOSC
3
ATR0841
4818AS–DVD–09/04
Pin Configuration
Figure 2. Pinning QFN24
RFB
RFA
E2
NE2
E3
NE3
IOUTA
GND
RSA
RSB
IOUTB
SELA
I4
I3
I2
IR
VCC
VCC
E4
NE4
ENOSC
ENABLE
VCC
VCC
24 23 22 21 20 19
7 8 9 10 11 12
18
17
16
15
14
13
1
2
3
4
5
6
Pin Description
Pin Symbol Type Function
1 RFB Analog External resistor to ground sets frequency of oscillator B
2 RFA Analog External resistor to ground sets frequency of oscillator A
3 E2 Digital +LVDS control of channel 2
4 NE2 Digital -LVDS control of channel 2
5 E3 Digital +LVDS control of channel 3
6 NE3 Digital -LVDS control of channel 3
7 E4 Digital +LVDS control of channel 4
8 NE4 Digital -LVDS control of channel 4
9 ENOSC Digital Enables RF oscillator (high active)
10 ENABLE Digital Enables output current (high active)
11 VCC Supply +5 V power supply
12 VCC Supply +5 V power supply
13 SELA Digital High: selects IOUTA, RSA, RFA
Low: selects IOUTB, RSB, RFB
14 IOUTB Analog Output current source B for laser diode
15 RSB Analog External resistor to ground sets swing of oscillator B
16 RSA Analog External resistor to ground sets swing of oscillator A
17 GND Supply Ground
18 IOUTA Analog Output current source A for laser diode
19 VCC Supply +5 V power supply
20 VCC Supply +5 V power supply
21 IR Analog Reference current input read channel (input impedance 500 Ω to ground)
22 I2 Analog Reference current input channel 2 (input impedance 500 Ω to ground
23 I3 Analog Reference current input channel 3 (input impedance 500 Ω to ground)
24 I4 Analog Reference current input channel 4 (input impedance 500 Ω to ground)
Paddle GND Supply Ground
4 ATR0841
4818AS–DVD–09/04
Absolute Maximum Ratings
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating
only and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of this
specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
Parameters Symbol Value Unit
Supply voltage VCC -0.5 to +6.1 V
Input voltage at any input Vin -0.5 to VCC + 0.5 V
Power dissipation Pmax 0.7(1) to 1(2) W
Output voltage Vout -0.5 to VCC - 1 V
Junction temperature Tj150 °C
Storage temperature Tstg -65 to +125 °C
Notes: 1. RthJA ≤ 115 K/W at Tamb = 70°C
2. RthJA ≤ 115 K/W at Tamb = 25°C
Thermal Resistance
Parameters Symbol Value Unit
Junction ambient, QFN24 RthJA 50(1) K/W
Note: 1. Measured with multi-layer test board (JDEC standard)
Recommended Operating Range
Parameters Symbol Value Unit
Supply voltage VCC 4.5 to 5.9 V
Input current IIR, II2, II3, II4 < 1.5 mA
External resistor to GND to set oscillator frequency RFA, RFB > 3 kΩ
External resistor to GND to set oscillator swing RSA, RSB > 1 kΩ
Operating temperature range Tamb 0 to +70 °C
5
ATR0841
4818AS–DVD–09/04
Package Information
Ordering Information
Extended Type Number Package Remarks
ATR0841-PFQG Lead free QFN24, 4 mm × 4 mm Taped and reeled
Printed on recycled paper.
Disclaimer: Atmel Corporation makes no warranty for the use of its products, other than those expressly contained in the Company’s standard
warranty which is detailed in Atmel’s Terms and Conditions located on the Company’s web site. The Company assumes no responsibility for any
errors which may appear in this document, reserves the right to change devices or specifications detailed herein at any time without notice, and
does not make any commitment to update the information contained herein. No licenses to patents or other intellectual property of Atmel are
granted by the Company in connection with the sale of Atmel products, expressly or by implication. Atmel’s products are not authorized for use
as critical components in life support devices or systems.
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4818AS–DVD–09/04
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