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19-2597; Rev 2; 8/06
3.2Gbps Compact SFP VCSEL Driver
General Description
The MAX3741 is a high-speed VCSEL driver for small-
form-factor (SFF) and small-form-factor pluggable (SFP)
fiber-optic LAN transmitters. It contains a bias generator,
laser modulator, and peaking current option to improve
VCSEL edge speed. The driver accommodates common
cathode and differential configurations.
The MAX3741 operates up to 3.2Gbps. It can switch up
to 15mA of laser modulation current and source up to
15mA of bias current. The MAX3741 is designed to inter-
face with a digital potentiometer and control circuitry.
The MAX3741 accommodates various VCSEL packages,
including low-cost TO-46 headers.
The MAX3741 is available in a compact 3mm x 3mm
16-pin thin QFN package and operates over a tempera-
ture range of -40°C to +85°C.
♦
2mA to 15mA Modulation Current
♦
1mA to 15mA Bias Current
♦
Optional Peaking Current to Improve VCSEL Edge
Speed
♦
Supports Common Cathode and Differential
Configuration
♦
3mm
×
3mm 16-Pin Thin QFN Package
Features
MAX3741
Applications
Multirate (1Gbps to 3.2Gbps) SFP/SFF Modules
Gigabit Ethernet Optical Transmitters
Fibre Channel Optical Transmitters
PART
Ordering Information
TEMP
RANGE
PIN-
PACKAGE
16 Thin QFN
16 Thin QFN
PKG.
CODE
T1633F-3
T1633F-3
-40°C to +85°C
MAX3741ETE
MAX3741HETE* -40°C to +85°C
*Hybrid
lead-free package. See the
Hybrid Lead-Free Package
section.
Typical Application Circuit
+3.3V
Pin Configuration
V
CC
BIAS
0.1µF
IN+
IN-
0.1µF
MAX3741
OUT+
0.01µF
OUT-
50Ω
TX_DISABLE
BIASSET
MODSET
BIASMON
GND PEAKSET
R
PEAKSET
0.01µF
L1*
16
15
14
13
TX_DISABLE
IN+
IN-
N.C.
BIAS
12
BIASMON
11
OUT+
10
OUT-
9
GND
1
2
3
4
5
V
CC
6
7
PEAKSET
8
MAX3741
3mm x 3mm
V
CC
TOP VIEW
BIASSET
0.01µF
V
CC
R
BIASSET
R
MODSET
R
MON
THIN QFN
EXPOSED PAD IS CONNECTED TO GND.
THIS SYMBOL REPRESENTS A TRANSMISSION LINE OF
CHARACTERISTIC IMPEDANCE Zo = 50Ω.
* FERRITE BEAD, MURATA BLM18HD102SN1B
________________________________________________________________
Maxim Integrated Products
MODSET
GND
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.
3.2Gbps Compact SFP VCSEL Driver
MAX3741
ABSOLUTE MAXIMUM RATINGS
Supply Voltage (V
CC
) ............................................-0.5V to +5.0V
Voltage at TX_DISABLE, IN+, IN-, MODSET,
PEAKSET, BIASSET, BIAS, BIASMON .......-0.5V to (V
CC
+ 0.5V)
Voltage at OUT+, OUT- .........................(V
CC
- 2V) to (V
CC
+ 2V)
Current into OUT+, OUT- ....................................................60mA
Continuous Power Dissipation (T
A
= +85°C)
16-Lead Thin QFN (derate 25mW/°C above +85°C) ..........2W
Operating Temperature Range .......................... -40°C to +85°C
Storage Temperature Range .............................-55°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°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.
ELECTRICAL CHARACTERISTICS
(V
CC
= +2.97V to +3.63V, T
A
= -40°C to +85°C. Typical values are at V
CC
= +3.3V, T
A
= +25°C, unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
TX_DISABLE set low,
peaking is not used
(Note 1)
I
MOD
= 2mA
P-P
I
MOD
= 15mA
P-P
MIN
TYP
41
51
14
0.15
80
V
IH
V
IL
t_off
TX_DISABLE Time
t_on
Input Leakage
BIAS GENERATOR
(Note 4)
Bias Current
Accuracy of Programmed Bias
Current
Bias Current During Disable
BIASMON Gain
LASER MODULATOR
(Note 5)
Data Input Voltage Swing
Output Resistance
Modulation Current
V
ID
R
OUT
I
MOD
Total differential signal
Single-ended resistance at OUT+, OUT-
Min
Max
15
250
63
2200
80
2
mV
P-P
Ω
mA
P-P
I
BIAS
∆I
BIAS
I
BIAS_OFF
TX_DISABLE high
0.095
0.115
Min
Max
15
-8
+8
10
0.135
1
mA
%
µA
mA/mA
Time from rising edge of TX_DISABLE to
I
BIAS
= I
BIAS_OFF
and I
MOD
= I
MOD_OFF
(Note 3)
Time from falling edge of TX_DISABLE to
I
BIAS
= 15mA and I
MOD
= 15mA
P-P
V
CC
= 0V and V
TX_DISABLE
= 3.3V
0.2
2
0.8
3
µs
111
25
40
µA
105
65
mA
20
1
kΩ
V
V
MAX
UNITS
Supply Current
I
CC
Additional current when peaking is used
(Note 2)
I
CC-SHDW
Total current when TX_DISABLE is high
TX_DISABLE INPUT
Input Impedance
Input High Voltage
Input Low Voltage
2
_______________________________________________________________________________________
3.2Gbps Compact SFP VCSEL Driver
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +2.97V to +3.63V, T
A
= -40°C to +85°C. Typical values are at V
CC
= +3.3V, T
A
= +25°C, unless otherwise noted.)
PARAMETER
Programmable Peaking Current
Peaking Current Duration
Tolerance of Programmed
Modulation Current
Modulation Transition Time
Deterministic Jitter
Random Jitter
Laser Modulation During Disable
Differential Input Resistance
Input Bias Voltage
V
IN
t
R
, t
F
DJ
RJ
I
MOD_OFF
5mA
P-P
≤
I
MOD
≤
15mA
P-P
(Note 3)
5mA
P-P
≤
I
MOD
≤
15mA
P-P
(Notes 3, 6)
(Note 3)
Differential input voltage at 2200mV
P-P
85
-10
65
13
1
15
100
V
CC
-
0.3
SYMBOL
I
PEAK
Min
Max
CONDITIONS
MIN
TYP
0.2
2
80
+10
95
25
4
50
115
MAX
UNITS
mA
ps
%
ps
ps
P-P
ps
RMS
µA
P-P
Ω
V
MAX3741
Note 1:
Note 2:
Note 3:
Note 4:
Note 5:
Note 6:
Measured with R
BIASSET
= 1.87kΩ (I
BIAS
≈
15mA). Supply current excludes I
BIAS
.
Tested with R
PEAK
= 1.18kΩ.
Guaranteed by design and characterization.
V
BIAS
is less than V
CC
- 0.7V.
Measured electrically with a 50Ω load AC-coupled to OUT+.
Deterministic jitter is the peak-to-peak deviation from the ideal time crossings measured with a K28.5 bit pattern at 3.2Gbps
(00111110101100000101).
Typical Operating Characteristics
(V
CC
= +3.3V, T
A
= 25°C, measured electrically with a 50Ω load AC-coupled to OUT+, unless otherwise noted.)
ELECTRICAL EYE
MAX3741 toc01
ELECTRICAL EYE WITH PEAKING
MAX3741 toc02
ELECTRICAL EYE WITH PEAKING
MAX3741 toc03
3.2Gbps, K28.5, 10mA
MODULATION, NO PEAKING
3.2Gbps, K28.5, 10mA
MODULATION, R
PEAKSET
= 2.4kΩ
3.2Gbps, K28.5, 10mA
MODULATION, R
PEAKSET
= 500Ω
87mV/div
87mV/div
87mV/div
50ps/div
50ps/div
50ps/div
_______________________________________________________________________________________
3
3.2Gbps Compact SFP VCSEL Driver
MAX3741
Typical Operating Characteristics (continued)
(V
CC
= +3.3V, T
A
= 25°C, measured electrically with a 50Ω load AC-coupled to OUT+, unless otherwise noted.)
OPTICAL EYE
AT 2.125Gbps
MAX3741 toc04
OPTICAL EYE
MAX3741 toc05
DETERMINISTIC JITTER vs. I
MOD
24
20
16
12
8
4
0
MAX3741 toc06
(E
R
= 8.8dB, K28.5, 850nm VCSEL, WITH
2.3GHz O-TO-E CONVERTER)
(E
R
= 8.8dB, 1.063Gbps, K28.5, 850nm VCSEL, WITH
2.3GHz O-TO-E CONVERTER)
28
68ps/div
135ps/div
DETERMINISTIC JITTER (ps
P-P
)
0
5
10
15
MODULATION CURRENT (mA
P-P
)
RANDOM JITTER vs. I
MOD
MAX3741 toc07
BIAS CURRENT vs. R
BIASSET
MAX3741 toc08
I
MOD
vs. R
MODSET
14
12
10
8
6
4
2
0
MAX3741 toc09
4.0
3.5
RANDOM JITTER (ps
RMS
)
3.0
2.5
2.0
1.5
1.0
0.5
0
0
5
10
16
14
BIAS CURRENT (mA)
12
10
8
6
4
2
0
0
5
10
15
R
BIASSET
(kΩ)
20
25
16
MODULATION CURRENT (mA
P-P
)
15
30
0
2
4
6
R
MODSET
(kΩ)
8
10
12
MODULATION CURRENT (mA
P-P
)
I
BIASMON
vs. BIAS CURRENT
MAX3741 toc10
INPUT RETURN LOSS
MAX3741 toc11
OUTPUT RETURN LOSS
-2
-4
-6
S
22
(dB)
-8
-10
-12
-14
-16
MAX3741 toc12
1.8
1.6
1.4
I
BIASMON
(mA)
1.2
0
-5
-10
S
11
(dB)
-15
-20
-25
-30
-35
100M
DIFFERENTIAL
MEASUREMENT
0
1.0
0.8
0.6
0.4
0.2
0
0
4
8
BIAS CURRENT (mA)
12
16
-18
1G
FREQUENCY (Hz)
10G
-20
100M
1G
FREQUENCY (Hz)
10G
4
_______________________________________________________________________________________
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