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PDF AD9662 Data sheet ( Hoja de datos )
| Número de pieza | AD9662 | |
| Descripción | 3-Channel Laser Diode Driver | |
| Fabricantes | Analog Devices | |
| Logotipo |  |
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FEATURES
Current-controlled current source
with 3 input channels
Output current for Channel 3—315 mA
Output current for other channels—210 mA
Rise time/fall time of 0.8 ns
On-chip oscillator
Single 5 V power supply (±10%)
Low output overshoot
Low power consumption
APPLICATIONS
CD-RW drives
DVD-RW, DVD+RW, MO drives
Laser diode current switching
GENERAL DESCRIPTION
The AD9662 is a laser diode driver for high performance CD
and DVD recordable drives. It includes three channels for three
different optical power levels: the read channel generates a
continuous output power level, whereas Channel 2 and
Channel 3 are used as write channels having 0.8 ns rise/fall
times. All channel currents are summed at the IOUT pin. Each
channel’s output current is established by multiplying the
channel’s gain by the channel’s input current. The input current
for each of the input channels—INR, IN2, and IN3—can be set
either by using an external resistor that converts an input
voltage to a current or by directly using a current source.
An on-chip oscillator is provided to allow output current
modulation (to reduce laser mode hopping). Two external
resistors control the frequency and the amplitude swing of the
oscillator. The push-pull oscillator can swing up to 100 mA p-p
and has a frequency range of 200 MHz to 500 MHz.
3-Channel Laser Diode Driver
with Oscillator
AD9662
FUNCTIONAL BLOCK DIAGRAM
IN3
OUTEN3
CHANNEL 3
IN2
OUTEN2
CHANNEL 2
INR
OUTENR
READ CHANNEL
OUTPUT
IOUT
ENABLE
OSCEN
OSCILLATOR
RF RS
Figure 1. AD9662 3-Channel Laser Diode Driver
Rev. C
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or 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
www.analog.com
Fax: 781.461.3113
© 2005 Analog Devices, Inc. All rights reserved.
1 page  
ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter
Supply Voltage +VS
Pin 9, Pin 15, and Pin 16
Input Pins
Pin 1 and Pin 2
Pin 5
Pin 6, Pin 7, Pin 8, Pin 10, and Pin 11
Internal Power Dissipation1
16-Lead QSOP
Operating Temperature Range
Storage Temperature Range
Lead Temperature, Soldering 60 sec
Range
5.5 V
2.2 mA
1.6 mA
−0.8 V to +5.5 V
620 mW
0°C to +85°C
−65°C to +150°C
300°C
1 Power dissipation is specified on SEMI standard 4-layer board.
AD9662
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
ESD CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the
human body and test equipment and can discharge without detection. Although this product features
proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy
electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance
degradation or loss of functionality.
Rev. C | Page 5 of 16
5 Page 
The change in junction temperature can then be determined.
TJ = T1 + ΔVBE/(1.9 mV/°C)
AD9662
ICC
VCC
RS
5V –
V1, V2
+
1MΩ
ENR
IBE
10V
Figure 15. Junction Temperature Measurement Circuit
This 2-point measurement allows the rise in die temperature to
be calculated for any given power dissipation. The θJA of the
system can be calculated using the power dissipation of the LDD.
PD = VCC × ICC – VDIODE × IDIODE
θJA = (TJ – T1)/PD
Figure 16 shows a graph of the measured voltage between ENR
and VCC (VENR − VCC) vs. the die temperature. This graph was
constructed using a 2-layer evaluation board for the AD9662
(see Figure 17).
AD9662
Using the preceding method, actual data was taken to
determine the θJA of the AD9662 in the evaluation board.
Immediately after power-up, V1 was measured to be 593 mV.
The supply current was 27 mA. The AD9662 was adjusted to
deliver 200 mA into a 10 Ω load. This resulted in a total supply
current of 244 mA. After allowing the part to reach thermal
equilibrium, V2 measured 412 mV. The voltage drop across the
120 mΩ internal resistor due to the change in supply current
was then calculated.
(244 mA – 27 mA) × 120 mΩ = 26 mV
This 26 mV internal voltage drop was then added to the
measured voltage reduction to determine the actual ΔVBE.
ΔVBE = (593 mV – 412 mV + 26 mV) = 207 mV
The die temperature change measured 82.4°C. The output of
the AD9662 was at a voltage of 2 V. The part dissipated an
additional 600 mW of power (3 V × 200 mA). The θJA for the
AD9962 mounted on its 2-layer board was calculated to be:
600 mW/82.4°C = 137°C/W.
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
20 40 60 80 100 120 140
TEMPERATURE (°C)
Figure 16. VENR − VCC vs. Internal Temperature
160
Rev. C | Page 11 of 16
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet AD9662.PDF ] | |
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