19-0323; Rev 5; 5/01
Single +5V, Fully Integrated,
1.25Gbps Laser Diode Driver
_______________General Description
The MAX3261 is a complete, easy-to-program, single
+5V-powered, 1.25Gbps laser diode driver with com-
plementary enable inputs and automatic power control
(APC). The MAX3261 accepts differential PECL inputs
and provides complementary output currents. A tem-
perature-stabilized reference voltage is provided to
simplify laser current programming. This allows modu-
lation current to be programmed up to 30mA and bias
current to be programmed up to 60mA with two exter-
nal resistors.
Complementary enable inputs allow the MAX3261 to
interface with open-fiber-control architecture—a feature
not found in other 1.25Gbps laser diode drivers.
An APC circuit is provided to maintain constant laser power
in transmitters that use a monitor photodiode. Only two
external components are required to implement the APC
function.
The MAX3261’s fully integrated feature set includes a
TTL-compatible laser failure indicator and a program-
mable slow-start circuit to prevent laser damage. The
slow-start is preset to 50ns and can be extended by
adding an external capacitor.
____________________________Features
o
Rise Times Less than 250ps
o
Differential PECL Inputs
o
Single +5V Supply
o
Automatic Power Control
o
Temperature-Compensated Reference Voltage
o
Complementary Enable Inputs
MAX3261
______________Ordering Information
PART
MAX3261CCJ
MAX3261ECJ
MAX3261E/D
TEMP. RANGE
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
32 TQFP
32 TQFP
Dice*
*Dice
are designed to operate over a -40°C to +140°C junction
temperature (Tj) range. Tested and guaranteed at Tj = +25°C.
________________________Applications
Laser Diode Transmitters
531Mbps and 1062Mbps Fibre Channel
622Mbps SDH/SONET
Gigabit Ethernet
__________Typical Operating Circuit
+5V
+5V
V
CC
A V
CC
B
VIN+
PECL
INPUTS
VIN-
GND A
GND B
ENB+
TO OPEN
FIBER
CONTROL
OUT+
+5V
__________________Pin Configuration
V
CC
A
V
CC
A
V
CC
A
GNDA
OUT+
GNDA
OUT-
GNDA
TOP VIEW
PHOTO-
DIODE
LASER
MAX3261
IPIN
32
31
30
29
28
27
26
25
IBIASOUT
ENB-
SLWSTRT
VREF1
VREF2
OUT-
FAILOUT
IBIASFB
Z
O
= 25Ω
MICROSTRIP
2.7k
+5V
GNDA
GNDA
IPIN
SLWSTRT
GNDB
VREF2
IPINSET
FAILOUT
1
2
3
4
5
6
7
8
MAX3261
24
23
22
21
20
19
18
17
IBIASOUT
IMODSET
IBIASSET
IBIASFB
OSADJ
VREF1
V
CC
B
ENB+
IBIASSET
IMODSET
OSADJ
IPINSET
________________________________________________________________
Maxim Integrated Products
GNDB
VIN+
GNDB
VIN-
GNDB
V
CC
B
V
CC
B
ENB-
9
10
11
12
13
14
15
16
TQFP
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
Single +5V, Fully Integrated,
1.25Gbps Laser Diode Driver
MAX3261
ABSOLUTE MAXIMUM RATINGS
Terminal Voltage (with respect to GND)
Supply Voltages (V
CC
A, V
CC
B) ...............................-0.3V to 6V
VIN+, VIN-, FAILOUT...............................................0V to V
CC_
OUT+, OUT-, IBIASOUT .......................................1.5V to V
CC_
ENB+, ENB- .......................V
CC_
or 5.5V, whichever is smaller
Differential Input Voltage (
|
VIN+ - VIN-
|
) ...........................3.8V
Input Current
IBIASOUT ............................................................0mA to 75mA
OUT+, OUT- ........................................................0mA to 40mA
IBIASSET ........................................................0mA to 1.875mA
IMODSET...............................................................0mA to 2mA
IPIN, IPINSET, OSADJ...........................................0mA to 2mA
FAILOUT..............................................................0mA to 10mA
IBIASFB................................................................-2mA to 2mA
Output Current
VREF1, VREF2.....................................................0mA to 20mA
SLWSTRT ..............................................................0mA to 5mA
Continuous Power Dissipation (T
A
= +70°C)
TQFP (derate 10.2mW/°C above +70°C)......................816mW
Operating Temperature Ranges
MAX3261CCJ ......................................................0°C to +70°C
MAX3261ECJ ...................................................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-55°C to +175°C
Processing Temperature (die) .........................................+400°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
DC ELECTRICAL CHARACTERISTICS
(V
CC
= V
CC
A = V
CC
B = +4.75V to +5.25V, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at V
CC
= +5V and
T
A
= +25°C.) (Note 1)
PARAMETER
Range of Programmable Laser
Bias Current
Reference Voltage
Available Reference Current
Supply Current
PECL Input High
PECL Input Low
TTL Input High
TTL Input Low
FAILOUT Output High
FAILOUT Output Low
SYMBOL
I
BIAS
V
REF
I
REF
I
VCC
V
IH
V
IL
V
IH
V
IL
V
OH
V
OL
Loaded with 2.7kΩ pull-up resistor to V
CC
Loaded with 2.7kΩ pull-up resistor to V
CC
4.5
0.5
2
0.8
(Note 2)
V
CC
- 1.165
V
CC
- 1.475
T
A
= +25°C
3.15
3.3
12
50
CONDITIONS
MIN
TYP
MAX
60
3.55
UNITS
mA
V
mA
mA
V
V
V
V
V
V
Note 1:
Dice are tested at T
A
= +25°C.
Note 2:
I
VCC
= I
VCC
A + I
VCC
B, I
BIAS
= 60mA, I
MOD
= 30mA, and I
PIN
= 140µA.
AC ELECTRICAL CHARACTERISTICS
(V
CC
= V
CC
A = V
CC
B = +4.75V to +5.25V, R
LOAD
(at OUT+ and OUT-) = 25Ω connected to V
CC
, T
A
= -40°C to +85°C, unless other-
wise noted. Typical values are at V
CC
= +5V and T
A
= +25°C.) (Note 3)
PARAMETER
Range of Programmable
Modulation Current
Modulation-Current Rise and
Fall Time
Aberrations, Rising and Falling
Edge
Modulation-Current Pulse-
Width Distortion
PWD
SYMBOL
I
MOD
t
R
, t
F
CONDITIONS
Minimum differential input
swing is 1100mVp-p (Note 4)
I
BIAS
= 25mA, I
MOD
= 12mA, 4ns unit
interval; measured from 10% to 90%.
I
MOD
= 12mA,
T
A
= +25°C
MAX3261E/D
MAX3261ECJ
MIN
TYP
MAX
30
250
±10
±15
80
UNITS
mA
ps
%
ps
I
BIAS
= 25mA, I
MOD
= 12mA, 4ns unit interval
Note 3:
AC characteristics are guaranteed by design and characterization.
Note 4:
An 1100mVp-p differential is equivalent to complementary 550mVp-p signals on VIN+ and VIN-.
2
_______________________________________________________________________________________
Single +5V, Fully Integrated,
1.25Gbps Laser Diode Driver
__________________________________________Typical Operating Characteristics
(MAX3261E/D, load at OUT+ and OUT- = 25Ω, V
CC
= V
CC
A = V
CC
B = +5V, T
A
= +25°C, unless otherwise noted.)
EYE DIAGRAM
(622Mbps, LOAD = 25Ω, NOT FILTERED)
MAX3261-1
MAX3261
EYE DIAGRAM
(622Mbps, LOAD AT OUT- = 1300nm
LASER WITH 467MHz BESSEL FILTER)*
MAX3261-2
EYE DIAGRAM
(1062Mbps, LOAD = 25Ω, NOT FILTERED)
MAX3261-3
250.3mV
265mV
250.3mV
50mV/div
30mV/div
-250mV
38.23ns
200ps/div
40.23ns
-35mV
38.14ns
200ps/div
40.14ns
50mV/div
-250mV
38.13ns
117ps/div
39.3ns
EYE DIAGRAM
(1062Mbps, LOAD AT OUT- = 1300nm
LASER WITH 800MHz BESSEL FILTER)*
MAX3261-4
MAX3261CCJ EYE DIAGRAM
(622Mbps, LOAD AT OUT- = 1300nm
LASER WITH 467MHz BESSEL FILTER)*
MAX3261-5
MAX3261CCJ EYE DIAGRAM
(1062Mbps, LOAD AT OUT- = 1300nm
LASER WITH 800MHz BESSEL FILTER)*
MAX3261-6
450mV
265mV
513.7mV
50mV/div
30mV/div
-50mV
38.74ns
117ps/div
39.91ns
-35mV
38.15ns
200ps/div
40.15ns
58mV/div
-66.2mV
37.78ns
117ps/div
38.95ns
R
BIASSET
vs. BIAS CURRENT
MAX3261-07
R
MODSET
vs. MODULATION CURRENT
MAX3261-08
R
PINSET
vs. MONITOR CURRENT
MAX3261-09
8
7
6
R
BIASSET
(kΩ)
5
4
3
2
1
0
0
20
I
BIAS
(mA)
* LASER = EPITAXX EDL 1300RFC TO-STYLE HEADER
40
12
10
R
MODSET
(kΩ)
8
6
4
DIFFERENTIAL INPUT
SWING = 1100 mVp-p
1,000,000
100,000
R
PINSET
(Ω)
0
5
10
15
20
25
30
10,000
1000
2
0
60
MODULATION CURRENT (mAp-p)
100
0
500
MONITOR CURRENT (µA)
1000
_______________________________________________________________________________________
3
Single +5V, Fully Integrated,
1.25Gbps Laser Diode Driver
MAX3261
____________________________Typical Operating Characteristics (continued)
(MAX3261E/D, LOAD at OUT+ = OUT- = 25Ω, V
CC
= V
CC
A = V
CC
B = +5V, T
A
= +25°C, unless otherwise noted.)
PERCENT CHANGE IN MODULATION
CURRENT vs. TEMPERATURE
MAX3261-10
PERCENT CHANGE IN BIAS
CURRENT vs. TEMPERATURE
MAX3261-11
SUPPLY CURRENT
vs. TEMPERATURE
48
SUPPLY CURRENT (mA)
46
44
42
40
38
36
MAX3261-12
10
8
% CHANGE (w.r.t. +25°C)
6
4
2
0
-2
-4
-6
-8
-10
0
20
40
60
3
APC DISABLED
% CHANGE (w.r.t. +25°C)
2
50
1
0
-1
-2
80
0
10
20
30
40
50
60
70
80
TEMPERATURE (°C)
TEMPERATURE (°C)
34
0
20
40
60
80
TEMPERATURE (°C)
ALLOWABLE R
OSADJ
vs. MODULATION CURRENT
MAXIMUM MODULATION CURRENT (mAp-p)
MAX3261-13
MAXIMUM MODULATION CURRENT
vs. MINIMUM DIFFERENTIAL
INPUT SIGNAL AMPLITUDE
35
30
25
20
15
10
5
0
0
400
800
1200
1600
2000
MINIMUM DIFFERENTIAL
INPUT SIGNAL AMPLITUDE (mVp-p)
R
MODSET
= 1.2kΩ
R
OSADJ
= 2kΩ
MAX3261-14
12
10
8
6
4
2
0
0
5
10
15
20
25
ALLOWABLE
RANGE
40
ALLOWABLE R
OSADJ
(kΩ)
30
MODULATION CURRENT (mAp-p)
4
_______________________________________________________________________________________
Single +5V, Fully Integrated,
1.25Gbps Laser Diode Driver
______________________________________________________________Pin Description
PIN
1, 2, 25,
27, 29
3
4
5, 9,
11, 13
6
7
8
10
12
14, 15, 18
16
17
19
20
21
22
23
24
26
28
30, 31, 32
NAME
GNDA
IPIN
SLWSTRT
GNDB
VREF2
IPINSET
FAILOUT
VIN+
VIN-
V
CC
B
ENB-
ENB+
VREF1
OSADJ
IBIASFB
IBIASSET
IMODSET
IBIASOUT
OUT-
OUT+
V
CC
A
FUNCTION
Ground for Bias and Modulation Current Drivers
Monitor Photodiode Current Input. Connect IPIN to photodiode’s anode.
Slow-Start Capacitor Input. Connect capacitor to ground or leave unconnected to set start-up time,
t
STARTUP
= 25.4kΩ (C
SLWSTRT
+ 2pF).
Ground for Voltage Reference and Automatic Power-Control Circuitry
Temperature-Compensated Reference Output. VREF2 is internally connected to VREF1.
Monitor Photodiode Programming Input. Connect IPINSET to VREF1 or VREF2 through a resistor to
set the monitor current when using automatic power control (see
Typical Operating Characteristics).
Failout Output. Active-low, open-collector TTL output indicates if automatic power-control loop is out
of regulation due to insufficient monitor-diode current (when V
IPIN
is below the 2.6V threshold).
Connect FAILOUT to V
CC_
through a 2.7kΩ pull-up resistor.
Noninverting PECL Data Input
Inverting PECL Data Input
+5V Supply Voltage for Voltage Reference and Automatic Power-Control Circuitry. Connect V
CC
B to
the same potential as V
CC
A, but provide separate bypassing for V
CC
A and V
CC
B.
Inverting Enable TTL Input. Output currents are enabled only when ENB+ is high and ENB- is low.
Noninverting Enable TTL Input. Output currents are enabled only when ENB+ is high and ENB- is low.
Temperature-Compensated Reference Output. VREF1 is internally connected to VREF2.
Overshoot-Adjust Input. Connect to internal voltage reference through a resistor to adjust the over-
shoot of the modulation output signal (see
Typical Operating Characteristics).
Bias-Feedback Current Output. Output from automatic power-control circuit. Connect to I
BIASSET
when using APC.
Laser Bias Current-Programming Input. Connect to internal voltage reference through a resistor to set
bias current (see
Typical Operating Characteristics).
I
IBIASOUT
= 40 x (I
IBIASSET
+ I
IBIASFB
).
Laser Modulation Current-Programming Input. Connect to internal voltage reference through a resistor
to set modulation current (see
Typical Operating Characteristics).
I
MOD
= 20 x I
IMODSET
.
Laser Bias Current Output. Connect to laser cathode through an R-L compensation network (see the
Bias Network Compensation
section).
Modulation Output. When VIN+ is high and VIN- is low, OUT- sinks I
MOD
.
Modulation Output. When VIN+ is low and VIN- is high, OUT+ sinks I
MOD
.
+5V Supply Voltage for Bias and Modulation Current Drivers. Connect V
CC
A to the same potential as
V
CC
B, but provide separate bypassing for V
CC
A and V
CC
B.
MAX3261
_______________________________________________________________________________________
5
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