Data Sheet
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
3.3 V Dual-Loop 50 Mbps to 1.25 Gbps
Laser Diode Driver
ADN2848
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).
APPLICATIONS
SONET OC-1/3/12/24
SDH STM-0/1/4
Fibre Channel
Gigabit Ethernet
FUNCTIONAL BLOCK DIAGRAM
DEGRADE
IMPDMON
CLKSEL
IMMON
IBMON
V
CC
FAIL
GND
ALS
V
CC
IMODN
V
CC
LD
IMODP
V
CC
MPD
IMPD
DATAP
DATAN
I
MOD
CONTROL
PSET
I
BIAS
GND ERSET
ASET
I
BIAS
CLKP
CLKN
V
CC
R
Z
ADN2848
GND
GND
ERCAP
PAVCAP
LBWSET
02746-001
GND
GND
Figure 1.
Rev. B
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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
Data Sheet
Alarms .............................................................................................7
Monitor Currents ..........................................................................8
Data and Clock Inputs ..................................................................8
CCBIAS...........................................................................................8
I
BIAS
...................................................................................................8
Automatic Laser Shutdown ..........................................................8
Alarm Interfaces ............................................................................8
Power Consumption .....................................................................9
Laser Diode Interfacing ................................................................9
Optical Supervisor.........................................................................9
Outline Dimensions ....................................................................... 12
Ordering Guide .......................................................................... 12
REVISION HISTORY
2/13—Rev. A to Rev. B
Added EPAD Notation..................................................................... 6
Changes to Endnote ......................................................................... 8
Updated Outline Dimensions ....................................................... 12
Changes to Ordering Guide .......................................................... 12
8/06—Rev. 0 to Rev. A
Updated Format ..................................................................Universal
Changes to Figure 1 .......................................................................... 1
Changes to Specifications ................................................................ 3
Changes to Figure 8 ........................................................................ 10
Changes to Figure 9 to Figure11 ................................................... 11
Updated Outline Dimensions ....................................................... 12
Changes to Ordering Guide .......................................................... 12
1/03—Revision 0: Initial Version
Rev. B | Page 2 of 12
Data Sheet
SPECIFICATIONS
V
CC
= 3.0 V to 3.6 V. All specifications T
MIN
to T
MAX
, unless otherwise noted.
1
Typical values are specified at 25°C.
Table 1.
Parameter
LASER BIAS Current (I
BIAS
, ALS)
Output Current I
BIAS
Compliance Voltage
I
BIAS
ALS Response Time
CCBIAS Compliance Voltage
MODULATION CURRENT (IMODP, IMODN)
Output Current I
MOD
Compliance Voltage
I
MOD
Rise Time
2
Fall Time
2
Random Jitter
2
Pulse Width Distortion
2
MONITOR PD (MPD)
Current
Compliance Voltage
POWER SET INPUT (PSET)
Capacitance
Monitor Photodiode Current into RPSET Resistor
Voltage
EXTINCTION RATIO SET INPUT (ERSET)
Allowable Resistance Range
Voltage
ALARM SET (ASET)
Allowable Resistance Range
Voltage
Hysteresis
CONTROL LOOP
Time Constant
DATA INPUTS (DATAP, DATAN, CLKP, CLKN)
3
V p-p (Single-Ended, Peak-to-Peak)
Input Impedance (Single-Ended)
t
SETUP4
t
HOLD4
LOGIC INPUTS (ALS, LBWSET, CLKSEL)
V
IH
V
IL
ALARM OUTPUTS (FAIL, DEGRADE)
V
OH
V
OL
IBMON, IMMON, IMPDMON
IMMON Division Ratio
IMPDMON
Compliance Voltage
Min
2
1.2
Typ
Max
100
V
CC
0.1
5
V
CC
80
V
CC
0.1
170
170
1.5
Unit
mA
V
mA
μs
V
mA
V
mA
ps
ps
ps
ps
μA
V
pF
μA
V
kΩ
V
kΩ
V
%
sec
sec
500
50
50
100
2.4
0.8
2.4
0.8
100
1
0
V
CC
− 1.2
mV
Ω
ps
ps
V
V
Internal 30 kΩ pull-up
V
V
A/A
A/A
V
ADN2848
Conditions/Comments
I
BIAS
When ALS asserted
I
BIAS
< 10% of nominal
1.2
5
1.5
80
80
1
15
50
When ALS asserted
RMS
I
MOD
= 40 mA
Average current
1200
1.65
80
1200
1.3
25
1.3
25
1.3
50
1.1
1.2
1.1
1.2
1.1
Average current
1.2
1.2
1.2
5
0.22
2.25
Low loop bandwidth selection
LBWSET = GND
LBWSET = V
CC
Data and clock inputs are
ac-coupled
See Figure 2
See Figure 2
100
Rev. B | Page 3 of 12
ADN2848
Parameter
SUPPLY
I
CC 5
V
CC 6
1
2
Data Sheet
Min
Typ
50
3.3
Max
Unit
mA
V
Conditions/Comments
I
BIAS
= I
MOD
= 0
3.0
3.6
Temperature range is −40°C to +85°C.
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.
5
I
CCMIN
for power calculation on Page 9 is the typical I
CC
given.
6
All V
CC
pins should be shorted together.
SETUP
HOLD
t
S
t
H
DATAP/DATAN
CLKP
Figure 2. Setup and Hold Time
Rev. B | Page 4 of 12
02746-002
Data Sheet
ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter
V
CC
to GND
Digital Inputs
(ALS, LBWSET, CLKSEL)
IMODN, IMODP
Operating Temperature Range
Industrial
Storage Temperature Range
Junction Temperature (T
J
Max)
32-Lead LFCSP_VQ Package
Power Dissipation
1
θ
JA
Thermal Impedance
2
Lead Temperature (Soldering for 10 sec)
1
2
ADN2848
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.
Rating
4.2 V
−0.3 V to V
CC
+ 0.3 V
V
CC
+ 1.2 V
−40°C to +85°C
−65°C to +150°C
150°C
(T
J
Max – T
A
)/θ
JA
W
32°C/W
300°C
Power consumption formulas are provided on Page 9.
θ
JA
is defined when device is soldered in a 4-layer board.
ESD CAUTION
Rev. B | Page 5 of 12
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