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AD9665 Schematic ( PDF Datasheet ) - Analog Devices

Teilenummer AD9665
Beschreibung Laser Diode Driver
Hersteller Analog Devices
Logo Analog Devices Logo 




Gesamt 17 Seiten
AD9665 Datasheet, Funktion
Data Sheet
4-Channel, LVDS, Dual-Output,
Laser Diode Driver with Oscillator
AD9665
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.
W3SET
W3DIS
W3DISN
FUNCTIONAL BLOCK DIAGRAM
WRITE
CHANNEL 3
W2SET
W2DIS
W2DISN
WRITE
CHANNEL 2
OUTPUT A LD1
W1SET
W1DIS
W1DISN
RSET
RDIS
WRITE
CHANNEL 1
READ CHANNEL
OUTPUT B LD2
OSCEN
OSCILLATOR
ENABLE
INS OUTSEL
FADJ1 FADJ2 AADJ1 AADJ2
Figure 1. 4-Channel, LVDS, Laser Driver Block Diagram
W3DISN 1
W3DIS* 2
GND 3
GND 4
W2DISN 5
W2DIS* 6
W1DISN 7
W1DIS* 8
AD9665
LFCSP
5mm × 5mm
(Not to Scale)
24 INS
23 VDD
22 LD1
21 LD1
20 GND
19 LD2
18 LD2
17 VDD
*TTL ACTIVE LOW
NOTES
1. DNC = DO NOT CONNECT. LEAVE THIS PIN
FLOATING WITH NO EXTERNAL CONNECTION.
2. WHEN PULLING A HIGH CURRENT, ATTACH
HEAT SINK ON THE EXPOSED PAD.
Figure 2. 4-Channel, LVDS, Laser Driver Pin Configuration, See Table 3
Rev. F
Document Feedback
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibilityisassumedbyAnalogDevices for itsuse,nor foranyinfringementsofpatentsor other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarksandregisteredtrademarksarethepropertyoftheirrespectiveowners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700 ©2010–2015 Analog Devices, Inc. All rights reserved.
Technical Support
www.analog.com






AD9665 Datasheet, Funktion
Data Sheet
ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter
Supply Voltage (+VDD)
Pins 10, 11, 17, 23, 32
Input Pins
Pins 12, 13, 14, 15
Pins 1, 2, 5, 6, 7, 8, 9, 16, 24, 29, 30
Internal Power Dissipation1
5 mm × 5 mm, 32-Lead, Pad-Up LFCSP
Operating Temperature Range
Storage Temperature Range
Range
6V
2.2 mA
−0.8 V to +VDD
2W
−25°C to +85°C
−65°C to +150°C
1 Power dissipation is specified on semistandard 4-layer board.
AD9665
Stresses at or above those listed under Absolute Maximum
Ratings may cause permanent damage to the product. This is a
stress rating only; functional operation of the product at these
or any other conditions above those indicated in the operational
section of this specification is not implied. Operation beyond
the maximum operating conditions for extended periods may
affect product reliability.
ESD CAUTION
Rev. F | Page 5 of 16

6 Page









AD9665 pdf, datenblatt
Data Sheet
SHUTDOWN SUPPLY CURRENT VARIATION
The AD9665 defaults to TTL input mode when the ENABLE
pin is tied low (ENABLE = 0), regardless of the position of the
INS pin. Because of this, there can be additional supply current
due to the applied voltage on the read, write, or OSCEN enable
pins, the cause of which is an inverter located on the TTL input
ENABLE pins (see Figure 17).
+VDD
INPUT
OUTPUT
GND
Figure 17. Inverter Circuit
AD9665
Voltages close to GND or VDD are not sufficient to turn on
both transistors. However, as voltages vary from these extremes,
significant current can flow. Figure 18 shows how the power-
down current varies with voltage applied on the read, write, or
OSCEN enable pins.
Therefore, to ensure the lowest possible shutdown current,
the read, write, and OSCEN voltages should be tied to either
0 V or 5 V.
16
CHIP DISABLED
12
VALID
TTL LOW
8
VALID
TTL HIGH
4
NONVALID
TTL REGION
0
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
TTL VOLTAGE ON READ AND WRITE CHANNELS (V)
Figure 18. Read and Write TTL Enable Voltage vs. Supply Current
Rev. F | Page 11 of 16

12 Page





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