Analog Devices ADN2841 a Datasheet
Dual-Loop 50 Mbps–2.7 Gbps
a
FEATURES
50 Mbps to 2.7 Gbps Operation
Typical Rise/Fall Time 80 ps
Bias Current Range 2 to 100 mA
Modulation Current Range 5 to 80 mA
Monitor Photodiode Current 50 A to 1200 A
Closed-Loop Control of Power and Extinction Ratio
Laser Fail and Laser Degrade Alarms
Automatic Laser Shutdown, ALS
Dual MPD Functionality for DWDM
Optional Clocked Data
Full Current Parameter Monitoring
5 V Operation
48-Lead LFCSP Package
32-Lead LFCSP Package (Reduced Functionality)
APPLICATIONS
DWDM Dual MPD Wavelength Fixing
SONET OC-1/3/12/48
SDH STM-1/4/16
Fibre Channel
Gigabit Ethernet
Laser Diode Driver
ADN2841
GENERAL DESCRIPTION
The ADN2841 uses a unique control algorithm to control both
the average power and extinction ratio of the laser diode (LD)
after initial factory setup. External component count and PCB area
are low, since both power and extinction ratio control are fully
integrated. Programmable alarms are provided for laser fail (end
of life) and laser degrade (impending fail).
The ADN2841 has circuitry for a second monitor photodiode,
which enables DWDM wavelength control.
MPD
GND
GND
GND
V
CC
IMPD
IMPD2
PSET
ERSET
FUNCTIONAL BLOCK DIAGRAM
V
IBMON
IMMON
IMPDMON
IMPDMON2
ALS
FAIL
DEGRADE
I
MOD
CONTROL
I
BIAS
PAV CAPERCAP
GNDGND
CC
IMODN
CLKSEL
ADN2841
LBWSETIDTONE
CC
V
GND
IMODP
IBIAS
ASET
GND
DATAP
DATAN
CLKP
CLKN
V
CC
LD
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. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700 www.analog.com
Fax: 781/326-8703 © Analog Devices, Inc., 2002
ADN2841–SPECIFICATIONS
(VCC = 5 V 10%. All specifications T
values as specified at 25C.)
MIN
to T
, unless otherwise noted1. Typical
MAX
Parameter Min Typ Max Unit Conditions/Comments
LASER BIAS (BIAS)
Output Current I
BIAS
Compliance Voltage 1.2
I
during ALS 0.1 mA
BIAS
2 100 mA
V
CC
V
ALS Response Time 10 µs
CCBIAS Compliance Voltage 1.2 V
MODULATION CURRENT (IMODP, IMODN)
Output Current I
MOD
Compliance Voltage 1.8 V
during ALS 0.1 mA
I
MOD
580mA
CC
V
Rise Time 80 120 ps
Fall Time 80 120 ps
Jitter 20 ps p-p
Pulsewidth Distortion 18 ps
MONITOR PD (MPD, MPD2)
Current 50 1200 µAAverage Current
Input Voltage 1.6 V
POWER SET INPUT (PSET)
Capacitance 80 pF
Input Current 50 1200 µAAverage Current
Voltage 1.15 1.23 1.35 V
EXTINCTION RATIO SET INPUT (ERSET)
Allowable Resistance Range 1.2 25 kΩ
Voltage 1.15 1.23 1.35 V
ALARM SET (ASET)
Allowable Resistance Range 1.2 25 kΩ
Voltage 1.15 1.23 1.35 V
Hysteresis 5 %
CONTROL LOOP
Time Constant 0.22 sec (LBWSET = GND)
2.25 sec (LBWSET = VCC)
DATA INPUTS (DATAP, DATAN, CLKP, CLKN)
AC-Coupled
2
V p-p (Single-Ended Peak-to-Peak) 100 500 mV
Input Impedance 50 Ω
t
SETUP
t
HOLD
3
3
150 95 ps
0 –70 ps
LOGIC INPUTS (ALS, LBWSET, CLKSEL)
V
IH
V
IL
2.4 V
0.8 V
ALARM OUTPUTS (Internal 30 kΩ Pull-Up)
V
OH
V
OL
2.4 V
0.8 V
IDTONE
Compliance Voltage VCC– 1.5 V User to Supply Current
Sink in the Range 50 µA
I
OUT
RATIO
I
IN
4
f
IN
0.01 1 MHz
2
to 4 mA
–2–
REV. A
ADN2841
WARNING!
ESD SENSITIVE DEVICE
Parameter Min Typ Max Unit Conditions/Comments
IBMON, IMMON, IMPDMON, IMPDMON2
IBMON, IMMON Division Ratio 100 A/A
IMPDMON, IMPDMON2 1 A/A
IMPDMON to IMPDMON2 Matching 1 % IMPD = 1200 µA
Compliance Voltage 0 VCC– 1.2 V
SUPPLY
5
I
CC
6
V
CC
NOTES
1
Temperature range: –40°C to +85°C.
2
When the voltage on DATAP is greater than the voltage on DATAN, the modulation current flows in the IMODP pin.
3
Guaranteed by design and characterization. Not production tested.
4
IDTONE may cause eye distortion.
5
ICC for power calculation is the typical ICC given.
6
All V
should be shorted together.
CCS
Specifications subject to change without notice.
4.5 5.0 5.5 V
0.05 A I
BIAS
= I
MOD
= 0
DATAP /DATAN
CLKP
SETUP
t
S
HOLD
t
H
Figure 1. Setup and Hold Time
ABSOLUTE MAXIMUM RATINGS
(TA = 25°C, unless otherwise noted.)
1
VCCto GND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 V
Operating Temperature Range
Industrial . . . . . . . . . . . . . . . . . . . . . . . . . . –40°Cto+85°C
Storage Temperature Range . . . . . . . . . . –65°Cto+150°C
Junction Temperature (T
) . . . . . . . . . . . . . . . . . . 150°C
J MAX
48-Lead LFCSP Package
Power Dissipation . . . . . . . . . . . . . . .(T
θ
Thermal Impedance2 . . . . . . . . . . . . . . . . . . . . 25°C/W
JA
– TA)/θJA mW
J MAX
Lead Temperature (Soldering for 10 sec) . . . . . . . . 300°C
ORDERING GUIDE
Model Temperature Range Package Description
ADN2841ACP-32 –40°C to +85°C 32-Lead LFCSP
ADN2841ACP-48 –40°C to +85°C 48-Lead LFCSP
ADN2841ACP-32-RL –40°C to +85°C 32-Lead LFCSP
ADN2841ACP-32-RL7 –40°C to +85°C 32-Lead LFCSP
ADN2841ACP-48-RL –40°C to +85°C 48-Lead LFCSP
32-Lead LFCSP Package
Power Dissipation . . . . . . . . . . . . . . . (T
θ
Thermal Impedance2 . . . . . . . . . . . . . . . . . . . . 32°C/W
JA
JMAX–TA
)/θJAmW
Lead Temperature (Soldering for 10 sec) . . . . . . . . . 300°C
NOTES
1
Stresses above those listed under Absolute Maximum Ratings may cause perma-
nent damage to the device. This is a stress rating only; functional operation of the
device at these or any other conditions above those listed in the operational
sections of this specification is not implied. Exposure to absolute maximum rating
conditions for extended periods may affect device reliability. Transient currents of
up to 100 mA will not cause SCR latch-up.
2
θJA is defined when the part is soldered onto a four-layer board.
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
the ADN2841 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. A
–3–
ADN2841
PIN CONFIGURATIONS
GND2 37
VCC2 38
IMODN 39
IMODN 40
GND2 41
IMODP 42
IMODP 43
GND2 44
GND2 45
IBIAS 46
IBIAS 47
CCBIAS 48
48-Lead LFCSP
36 GND2
35 IDTONE
34 GND2
33 IBMON
32 IMMON
31 GND3
30 VCC3
29 ALS
28 FAIL
27 DEGRADE
ADN2841
TOP VIEW
(Not to Scale)
PIN 1
INDICATOR
GND 1
PSET 5
ASET 3
ERSET 4
LBWSET 2
GND 6
IMPD 7
IMPDMON 8
IMPD2 10
IMPDMON2 9
26 CLKSEL
25 GND
24 GND
23 GND
22 CLKN
21 CLKP
20 GND1
19 DATAP
18 DATAN
17 GND1
16 VCC1
15 GND
14 PAVCAP
13 ERCAP
VCC4 12
GND4 11
LBWSET 1
ASET 2
ERSET 3
PSET 4
IMPD 5
IMPDMON 6
GND4 7
VCC4 8
32-Lead LFCSP
32 CCBIAS
31 IBIAS
30 GND2
29 GND2
28 IMODP
27 GND2
26 IMODN
25 VCC2
PIN 1
INDICATOR
ADN2841
TOP VIEW
(Not to Scale)
VCC1 11
CLKP 15
GND1 14
CLKN 16
DATAP 13
DATAN 12
ERCAP 9
PAV CAP 10
24 IBMON
23 IMMON
22 GND3
21 VCC3
20 ALS
19 FAIL
18 DEGRADE
17 CLKSEL
PIN FUNCTION DESCRIPTIONS
Pin No.
48-Lead 32-Lead Mnemonic Function
1 GND Supply Ground
21 LBWSET Select Low Loop Bandwidth (Active = VCC)
32 ASET Alarm Current Threshold Setting Pin
43 ERSET Extinction Ratio Set Pin
54 PSET Average Optical Power Set Pin
6 GND Ground
75 IMPD Monitor Photodiode Input
86 IMPDMON Mirrored Current from Monitor Photodiode
9 IMPDMON2 Mirrored Current from Monitor Photodiode 2 (for Use with Two MPDs)
10 IMPD2 Monitor Photodiode Input 2–(for Use with Two MPDs)
11 7 GND4 Supply Ground
12 8 VCC4 Supply Voltage
13 9 ERCAP Extinction Ratio Loop Capacitor
14 10 PAVCAP Average Power Loop Capacitor
15 GND Ground
16 11 VCC1 Supply Voltage
17 GND1 Supply Ground
18 12 DATAN Data, Negative Differential Terminal
19 13 DATAP Data, Positive Differential Terminal
20 14 GND1 Supply Ground
21 15 CLKP Data Clock Positive Differential Terminal, used if CLKSEL = V
22 16 CLKN Data Clock Negative Differential Terminal, used if CLKSEL = V
CC
CC
23 GND Ground
24 GND Ground
25 GND Ground
26 17 CLKSEL Clock Select (Active = V
), used if data is clocked into chip
CC
27 18 DEGRADE DEGRADE Alarm Output
28 19 FAIL FAIL Alarm Output
29 20 ALS Automatic Laser Shutdown
30 21 VCC3 Supply Voltage
31 22 GND3 Supply Ground
32 23 IMMON Modulation Current Mirror Output
33 24 IBMON Bias Current Mirror Output
34 GND2 Supply Ground
35 IDTONE IDTONE (Requires External Current Sink to Ground)
36 GND2 Supply Ground
–4–
REV. A
Loading...