4-Channel, LVDS, Dual-Output,
Laser Diode Driver with Oscillator
Data Sheet
Rev. F Document Feedback
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FEATURES
Dual, current-controlled output current sources with 4 input
channels
TTL-selectable output
Stable on-chip oscillators with independent frequency and
amplitude control
TTL- or LVDS-selectable write channel enables negative logic
Independent TTL oscillator enables positive logic
170 mA minimum output current for the read channel
510 mA minimum output current for Write Channel 1
330 mA minimum output current for Write Channel 2
165 mA minimum output current for Write Channel 3
950 mA typical total output current
Typical rise time/fall time of 0.8 ns
Low power consumption
Single 5 V power supply (±10%)
APPLICATIONS
DVD-R, DVD+R, DVD-RW, DVD+RW, DVD-RAM
supercombo drives
Magneto-optical (MO) drives
Laser diode current switching
OTDR laser drivers
GENERAL DESCRIPTION
The AD9665 is a laser diode driver for high performance CD-RW
and DVD recordable drives. It includes four channels for four
different optical power levels: the read channel generates a
continuous output power level, whereas Channel 1, Channel 2,
and Channel 3 can be used as write channels that can be
controlled with an LVDS or TTL interface. The WxDIS and
RDIS
pins are active low logic. The OSCEN pin is controlled by
an active high TTL signal. All active channels are summed at
the output where Write Channel 1 can contribute at least
325 mA output current, and Write Channel 2 and Write
Channel 3 can contribute at least 250 mA and 150 mA,
respectively. The level of the output current is set by an
external resistor, which converts this voltage into a current
at the WxSET pin.
An on-chip oscillator is provided to allow output current
modulation and to reduce laser-mode hopping. Four external
resistors permit the setting of two distinct values for the
frequency and swing of the oscillator. The oscillator can output
up to 100 mA p-p of current (push-pull oscillator) with a
frequency range of 200 MHz to 500 MHz.
FUNCTIONAL BLOCK DIAGRAM
WRITE
CHANNEL 3
WRITE
CHANNEL 2
WRITE
CHANNEL 1
READ CHANNEL
OSCILLATOR
OUTPUT A
OSCEN
RDIS
W1DISN
W1DIS
W1SET
W2DISN
W2DIS
W2SET
W3DISN
W3DIS
W3SET
RSET
OUTPUT B
LD1
LD2
F
ADJ1
F
ADJ2
A
ADJ1
A
ADJ2
INS OUTSEL
ENABLE
05269-001
Figure 1. 4-Channel, LVDS, Laser Driver Block Diagram
05269-050
*TTL ACTIVE LOW
NOTES
1. DNC = DO NOT CONNECT
. LEAVE THIS PIN
FLOA
TING WITH NO EXTERNAL CONNECTION.
2. WHEN PULLING A HIGH CURRENT,
ATTACH
HEAT SINK ON THE EXPOSED PAD.
V
DD
DNC
OSCEN
OUTSEL
F
ADJ1
F
ADJ2
A
ADJ1
A
ADJ2
INS
V
DD
LD1
LD1
GND
LD2
LD2
V
DD
AD9665
LFCSP
5mm × 5mm
(Not to Scale)
W3DIS*
GND
W2DIS*
W1DIS*
GND
W3DISN
W2DISN
W1DISN
V
DD
V
DD
W3SET
W2SET
W1SET
RSET
ENABLE
RDIS
24
23
22
21
1
2
3
32
20
19
18
17
9
10
1
1
12
13
14
15
16
4
5
6
7
8
31
30
29
28
27
26
25
Figure 2. 4-Channel, LVDS, Laser Driver Pin Configuration, See Table 3
