ADN2848 Analog Devices, ADN2848 Datasheet

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ADN2848

Manufacturer Part Number
ADN2848
Description
Manufacturer
Analog Devices
Datasheet

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Part Number
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Quantity
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Part Number:
ADN2848ACPZ
Manufacturer:
ADI
Quantity:
316
Part Number:
ADN2848ACPZ
Manufacturer:
ADI/亚德诺
Quantity:
20 000
FEATURES
50 Mbps to 1.25 Gbps operation
Single 3.3 V operation
Bias current range: 2 to 100 mA
Modulation current range: 5 to 80 mA
Monitor photo diode current: 50 μA to 1200 μA
50 mA supply current at 3.3 V
Closed-loop control of power and extinction ratio
Full current parameter monitoring
Laser fail and laser degrade alarms
Automatic laser shutdown (ALS)
Optional clocked data
Supports FEC rates
32-lead, 5 mm × 5 mm LFCSP_VQ package
APPLICATIONS
SONET OC-1/3/12/24
SDH STM-0/1/4
Fibre Channel
Gigabit Ethernet
Rev. A
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.
Trademarks and registered trademarks are the property of their respective owners.
MPD
GND
GND
V
CC
ERSET
PSET
IMPD
FUNCTIONAL BLOCK DIAGRAM
GND
3.3 V Dual-Loop 50 Mbps to 1.25 Gbps
CONTROL
ERCAP
Figure 1.
I
I
MOD
BIAS
GND
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
Fax: 781.461.3113
GENERAL DESCRIPTION
The ADN2848 uses a unique control algorithm to control both
the average power and the extinction ratio of the laser diode
(LD) after initial factory setup. External component count and
PCB area are low because both power and extinction ratio
control are fully integrated. Programmable alarms are provided
for laser fail (end of life) and laser degrade (impending fail).
V
CC
PAVCAP
IMODN
ADN2848
LBWSET
IMODP
I
ASET
©2006 Analog Devices, Inc. All rights reserved.
BIAS
GND
Laser Diode Driver
DATAP
DATAN
CLKP
CLKN
LD
V
CC
V
CC
R
Z
ADN2848
www.analog.com

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ADN2848 Summary of contents

Page 1

... Trademarks and registered trademarks are the property of their respective owners. 3.3 V Dual-Loop 50 Mbps to 1.25 Gbps GENERAL DESCRIPTION The ADN2848 uses a unique control algorithm to control both the average power and the extinction ratio of the laser diode (LD) after initial factory setup. External component count and PCB area are low because both power and extinction ratio control are fully integrated ...

Page 2

... ADN2848 TABLE OF CONTENTS Features .............................................................................................. 1 Applications....................................................................................... 1 General Description ......................................................................... 1 Functional Block Diagram .............................................................. 1 Revision History ............................................................................... 2 Specifications..................................................................................... 3 Absolute Maximum Ratings............................................................ 5 ESD Caution.................................................................................. 5 Pin Configuration and Function Descriptions............................. 6 Theory of Operation ........................................................................ 7 Control........................................................................................... 7 Loop Bandwidth Selection .......................................................... 7 REVISION HISTORY 8/06—Rev Rev. A Updated Format..................................................................Universal Changes to Figure 1.......................................................................... 1 Changes to Specifications ................................................................ 3 Changes to Figure 8 ...

Page 3

... Average current V pF μA Average current V kΩ V kΩ Low loop bandwidth selection sec LBWSET = GND sec LBWSET = Data and clock inputs are Ω ac-coupled ps See Figure 2 ps See Figure Internal 30 kΩ pull- A/A A/A − 1.2 V ADN2848 ...

Page 4

... ADN2848 Parameter SUPPLY Temperature range is −40°C to +85°C. 2 Measured into a 25 Ω load using a 0-1 pattern at 622 Mbps. 3 When the voltage on DATAP is greater than the voltage on DATAN, the modulation current flows in the IMODP pin. 4 Guaranteed by design and characterization. Not production tested. ...

Page 5

... 0.3 V section of this specification is not implied. Exposure to absolute 1.2 V maximum rating conditions for extended periods may affect CC device reliability. −40°C to +85°C −65°C to +150°C 150°C (T Max – T )/θ 32°C/W 300°C Rev Page ADN2848 ...

Page 6

... BIAS 32 CCBIAS Connected to Vcc When DC-Coupled to Laser Diode; Connected to I Diode—Current Sink. LBWSET 1 24 IBMON PIN 1 INDICATOR ASET 2 23 IMMON ERSET 3 22 GND3 ADN2848 PSET 4 CC TOP VIEW IMPD 5 20 ALS (Not to Scale) IMPDMON 6 19 FAIL GND4 7 18 DEGRADE ...

Page 7

... Figure 4. Laser Transfer Function CONTROL A monitor photodiode, MPD, is required to control the LD. The MPD current is fed into the ADN2848 to control the power and extinction ratio, continuously adjusting the bias current and modulation current in response to the laser’s changing threshold current and light-to-current slope efficiency. ...

Page 8

... Z AUTOMATIC LASER SHUTDOWN The ADN2848 ALS allows compliance to ITU-T-G958 (11/94), section 9.7. When ALS is logic high, both the bias and the modulation currents are turned off. Correct operation of ALS is confirmed by the FAIL alarm being raised when ALS is asserted ...

Page 9

... POWER CONSUMPTION The ADN2848 die temperature must be kept below 125°C. The LFCSP_VQ package has an exposed paddle. The exposed paddle should be connected in such a manner that the same potential as the ADN2848 ground pins. The θ package is shown under the Absolute Maximum Ratings. Power ...

Page 10

... DATAN 1µF PAVCAP ERCAP 9 1µF EACH V AS POSSIBLE TO THE ACTUAL SUPPLY PINS ON THE 8 ADN2848 AND THE LASER DIODE USED. CONSERVATIVE DECOUPLING WOULD INCLUDE 100pF ** ** CAPACITORS IN PARALLEL WITH 10nF CAPACITORS. 1.5kΩ 10nF 10nF 10nF GND Rev Page FAIL ...

Page 11

... CC 1µF PAVCAP ERCAP 9 1µF EACH V AS POSSIBLE TO THE ACTUAL SUPPLY PINS ON THE 8 ADN2848 AND THE LASER DIODE USED. CONSERVATIVE DECOUPLING WOULD INCLUDE 100pF ** ** CAPACITORS IN PARALLEL WITH 10nF CAPACITORS. 1.5kΩ 10nF 10nF 10nF GND Figure 11. A 1.244 Mbps Optical Eye. Temperature at 85°C. ...

Page 12

... INDICATOR 12° MAX 1.00 0.85 0.80 SEATING PLANE ORDERING GUIDE Model ADN2848ACP-32 ADN2848ACP-32-RL ADN2848ACP-32-RL7 1 ADN2848ACPZ-32 1 ADN2848ACPZ-32-RL 1 ADN2848ACPZ-32-RL7 Pb-free part. ©2006 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. C02746-0-10/06(A) 5.00 BSC SQ 0.60 MAX 24 0.50 BSC TOP 4 ...

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