MAX3643ETG+T [MAXIM]
Interface Circuit, BIPolar, 4 X 4 MM, ROHS COMPLIANT, TQFN-24;
| 型号： | MAX3643ETG+T |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Interface Circuit, BIPolar, 4 X 4 MM, ROHS COMPLIANT, TQFN-24 接口集成电路 |
| 文件： | 总15页 (文件大小：362K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
EVALUATION KIT AVAILABLE
MAX3643
155Mbps to 2.5Gbps Burst-Mode Laser Driver
General Description
Features
The MAX3643 burst-mode laser driver provides bias and
modulation current drive for PON burst-mode ONT appli-
cations. It is specifically designed for use with a low-cost
external controller for the APC (and if desired, AMC) loop.
A high-speed differential burst-enable input enables the
driver to switch the laser from a dark (output off) condition
to full on-condition in less than 2ns. When BEN is inac-
tive, typical modulation and bias currents are 5µA each.
♦ 10mA to 85mA Modulation Current
♦ 1mA to 70mA Bias Current
♦ Monitor Diode Sample and Hold
♦ 45ps Output Transition Time
♦ 2ns Turn-On/-Off Time
♦ Reference Voltage Generator
Laser modulation current can be set from 10mA to
85mA and bias current can be set from 1mA to 70mA
using the MODSET and BIASSET inputs. A sample-and-
hold circuit is provided to capture the monitor diode
output during short PON bursts, if needed, and the BEN
high-speed signal is mirrored on an LVCMOS output to
be used by the controller operating the APC/AMC loop.
♦ LVPECL High-Speed Inputs (Data, Burst Enable)
Ordering Information
PART
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
24 TQFN-EP*
24 TQFN-EP*
MAX3643ETG
MAX3643ETG+
The MAX3643 burst-mode laser driver is packaged in a
4mm x 4mm, 24-pin thin QFN package. It operates from
-40°C to +85°C.
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed paddle.
Applications
Pin Configuration appears at end of data sheet.
A/B/G/XGPON ONT Modules Up to 2.5Gbps
1.25Gbps IEEE EPON ONT Modules
Typical Application Circuit
3.3V
15Ω
10nH
3.3V
+3.3V
FILTER
130Ω
= 50Ω
130Ω
82Ω
V
CC
15Ω
5.6Ω
5.6Ω
SERIAL
DATA
SOURCE
IN+
IN-
Z
Z
OUT-
OUT+
BIAS+
0
= 50Ω
0
82Ω
10pF
75Ω
1kΩ
MAX3643
27pF
3.3V
+3.3V
10Ω
BIAS-
MDIN
130Ω
= 50Ω
130Ω
BEN+
BEN-
Z
Z
0
BURST
CONTROL
= 50Ω
MDOUT
0
82Ω
82Ω
BMD
MON1
3kΩ
1kΩ
1kΩ
DS1875
PON TRIPLEXER AND SFP
CONTROLLER
BEN
BIAS
MOD
For pricing, delivery, and ordering information, please contact Maxim Direct at
1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.
19-3848; Rev 4; 12/12
MAX3643
155Mbps to 2.5Gbps Burst-Mode Laser Driver
ABSOLUTE MAXIMUM RATINGS
Supply Voltage V
..............................................-0.5V to +4.0V
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range ............................-55°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Soldering Temperature (reflow)
CC
Current into BIAS-, BIAS+, OUT-, OUT+ .......-20mA to +150mA
Voltage at VMSET, VBSET, IN+, IN-, BEN+, BEN-, EN, MDIN,
MDOUT, BENOUT, BCMON ...................-0.5V to (V
+ 0.5V)
CC
Voltage at MODSET, BIASSET, VREF, IMAX ........-0.5V to +3.0V
Voltage at OUT-, OUT+, BIAS-, BIAS+ .....+0.3V to (V + 0.5V)
Lead(Pb)-free..............................................................+260°C
Containing lead(Pb)....................................................+240°C
CC
Continuous Power Dissipation (T = +85°C)
A
24-Pin TQFN, Multilayer Board
(derate 27.8mW/°C above +85°C)............................1807mW
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.
OPERATING CONDITIONS
PARAMETER
Supply Turn-On Time
Ambient Temperature
Data Rate
SYMBOL
CONDITIONS
MIN
0.001
-40
TYP
MAX
1000
+85
2500
1.4
UNITS
10% to 90%
ms
°C
Mbps
V
Voltage at VMSET, VBSET
Voltage at BCMON
Voltage at MDIN
0
0
0
1.4
V
2.56
V
ELECTRICAL CHARACTERISTICS
(V
= 3.0V to 3.6V, T = -40°C to +85°C. Typical values are at V
= 3.3V, T = +25°C, I
= 20mA, I
= 30mA, unless other-
CC
A
CC
A
BIAS
MOD
wise noted.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Excluding laser bias and mode currents,
max at I = 85mA, I = 70mA
Supply Current
I
32
51
mA
CC
MOD
BIAS
I/O SPECIFICATIONS
LVPECL Differential Input
V
V
= (V ) - (V
IN+
)
IN-
200
1600
mV
P-P
IN
IN
LVPECL Common-Mode Input
Voltage
V
1.49
-
V
1.32
-
V
-
CC
CC
CC
V
CM
V
V
/ 4
IN
V
0.2
-
CC
LVCMOS Output High Voltage
LVCMOS Output Low Voltage
BENOUT Propagation Delay
I
I
= -100μA
= 100μA
V
V
OH
OL
0.2
C = 20pF, from BEN zero crossing to 67%
L
CMOS level
T
30
ns
d
LVCMOS Input Pullup
75
kꢀ
μA
V
LVCMOS Input Current
V
= 0V or V = V
IN IN CC
50
LVCMOS Input High Voltage
LVCMOS Input Low Voltage
2.0
0.2
V
CC
0.8
V
BIAS GENERATOR SPECIFICATIONS
Bias Current Range
I
V
, V ꢁ 0.6V
BIAS+ BIAS-
1
70
50
mA
μA
BIAS
Bias Current, Burst Off
I
BEN = low or EN = high
5
BIAS, OFF
1mA ꢂ I
2mA ꢂ I
< 2mA, VBSET = VREF
< 10mA, VBSET = VREF
88
88
88
BIAS
BIAS
BIASSET Current Gain
G
BIAS
mA/mA
70
110
10mA ꢂ I
< 70mA, VBSET = VREF
82.5
94.5
BIAS
2
Maxim Integrated
MAX3643
155Mbps to 2.5Gbps Burst-Mode Laser Driver
ELECTRICAL CHARACTERISTICS (continued)
(V
= 3.0V to 3.6V, T = -40°C to +85°C. Typical values are at V
= 3.3V, T = +25°C, I
= 20mA, I
= 30mA, unless other-
CC
A
CC
A
BIAS
MOD
wise noted.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
ꢂ 70mA (Note 13)
ꢂ 70mA (Note 14)
MIN
-4.4
TYP
MAX
+4.4
+3.75
10
UNITS
%
BIASSET Current Gain Stability
BIASSET Current Gain Linearity
Bias Current Overshoot
5mA ꢂ I
5mA ꢂ I
BIAS
-3.75
%
BIAS
V
CC
turn-on/-off < 1s
%
Bias Current Monitor Gain
G
2mA ꢂ I
1mA ꢂ I
5mA ꢂ I
ꢂ 70mA, VBSET = VREF
< 5mA
11
14
4
17
mA/A
BSM
BIAS
BIAS
BIAS
Bias Current Monitor Gain
Stability
%
ꢂ 70mA
-5
+5
60
BIASSET Resistor
R
BIAS
40
50
5
ꢀ
MODULATOR SPECIFICATIONS
Modulation Current Range
Modulation Current Off
I
10
85
mA
μA
MOD
I
BEN = low or EN = high or V = low
120
MOD, OFF
IN
10mA ꢂ I
< 60mA
0.6
0.75
82.5
-4.4
-2.2
MOD
MOD
Instantaneous Voltage at OUT+
V
60mA ꢂ I
ꢂ 85mA
MODSET Current Gain
G
MOD
10mA < I
(Note 13)
(Note 14)
< 85mA, VMSET = VREF
88
0.5
94.5
+4.4
+2.2
mA/mA
MOD
MODSET Current Gain Stability
MODSET Current Gain Linearity
%
%
I
I
I
I
= 0.15mA, I
= 0.7mA
BIASSET
MODSET
MODSET
MODSET
MODSET
= I
= I
= I
= 0.15mA
= 0.4mA
= 0.55mA
1.7
1
MODSET, BIASSET Gain
Matching (Note 15)
BIASSET
BIASSET
BIASSET
%
1
Modulation Current Rise Time
Modulation Current Fall Time
Deterministic Jitter
t
20% to 80%
20% to 80%
(Note 3)
45
45
17
0.8
50
85
85
45
1.4
60
ps
ps
R
t
F
ps
P-P
RMS
ꢀ
Random Jitter
(Note 4)
ps
MODSET Resistor
R
40
MOD
MODSET, BIASSET OPERATIONAL AMPLIFIER SPECIFICATIONS
MODSET, BIASSET Voltage
Range
0.005
1.4
V
Voltage Error
(Note 5)
5
mV
μA
Input Leakage
VMSET and VBSET pins
0.1
1.5
TURN-OFF/-ON SPECIFICATIONS
Burst-Enable Time
(Notes 2, 6, 7)
(Notes 2, 6, 8)
2.3
2.0
ns
ns
Burst-Disable Time
SAMPLE/HOLD SPECIFICATIONS
MDIN Voltage Range
0.05
2.56
1
V
MDOUT Settling
Relative to final value at 3μs, C < 20pF
L
mV
Sample/Hold Droop
After 100μs (Note 9)
2.56
10
mV
%
V
CC
turn-on/-off < 1s, I
ꢁ 20mA
BIAS
Bias Current Overshoot
I
< 20mA
2
mA
BIAS
Maxim Integrated
3
MAX3643
155Mbps to 2.5Gbps Burst-Mode Laser Driver
ELECTRICAL CHARACTERISTICS (continued)
(V
= 3.0V to 3.6V, T = -40°C to +85°C. Typical values are at V
= 3.3V, T = +25°C, I
= 20mA, I
= 30mA, unless other-
CC
A
CC
A
BIAS
MOD
wise noted.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Final value measured after 10μs
(MDOUT - MDIN), burst width > 576ns
Sampling Error
3
14
mV
BANDGAP VOLTAGE REFERENCE SPECIFICATIONS
VREF Output
R > 10kꢀ, C < 50pF
1.175
1.235
1.295
V
L
L
MODULATION/BIAS CURRENT DISABLE
Enable Time
5mA < I
, 10mA < I
(Note 10)
5.5
375
15
μs
ns
kꢀ
BIAS
MOD
Disable Time
(Notes 2, 11)
R
Range
3
IMAX
R
R
R
= 3kꢀ
155
100
50
IMAX
IMAX
IMAX
Current Limit (Tested with I
BIAS
I
+I
mA
= 5kꢀ
150
75
BIAS MOD
= I
)
MOD
= 10kꢀ
OPTICAL EVALUATION
155.52Mbps
622.08Mbps
1.24416Gbps
2.48832Gbps
49
45
38
18
Eye Margin (Note 12)
%
Note 1: Electrical specifications are production tested at T = +25°C. Specifications over the entire operating temperature range
A
are guaranteed by design and characterization. Typical specifications are at T = +25°C, 3.3V.
A
Note 2: For 10mA ≤ I
≤ 85mA and 4mA ≤ I
≤ 70mA.
MOD
BIAS
7
7
Note 3: Deterministic jitter measured with a continuous pattern of 2 -1 PRBS, 80 ones, 2 -1 PRBS, 80 zeros at 1.25Gbps, and both
LVPECL inputs terminated by the network shown in Figure 3.
Note 4: Random jitter, rise time, fall time measured with 0000011111 pattern at 1.25Gbps.
Note 5: Voltage difference between VMSET and MODSET or VBSET and BIASSET excluding IR drops. The maximum operating
voltage at VMSET or VBSET must be less than 1.4V for proper operation.
Note 6: Turn-on/-off time is when the BEN+/BEN- LVPECL inputs are used to control modulation and bias currents.
Note 7: Burst-enable delay is measured between the time at which the rising edge of the differential burst-enable input reaches the
midpoint, and the time at which the combined output currents (bias plus modulation) reach 90% of their final level.
Note 8: Burst-disable delay is measured between the time at which the falling edge of the differential burst-enable input reaches the
midpoint, and the time at which the combined output currents (bias plus modulation) fall below 10% of the bias-on current.
Note 9: Droop measured with sample/hold output load of 10MΩ.
Note 10: Enable delay is measured between the time at which the falling edge of the EN input reaches ≤ 0.8V, and the time at which
the combined output currents (bias plus modulation) reach 90% of their final level.
Note 11: Disable delay is measured between the time at which the rising edge of the EN input reaches ≥ 2V, and the time at which
the combined output currents (bias plus modulation) fall below 10% of the bias-on current.
Note 12: Excelight SLT2886-LR laser.
Note 13: Current gain stability = [(Gain – nominal Gain) / nominal Gain], nominal Gain at V
Note 14: Gain linearity = (Gainmax – Gainmin), Gainavg = Gainmax + Gainmin
= 3.3V, T = +25°C.
A
CC
Gainavg
2
Gainmod / Gainbias − Gainmodnom / Gainbiasnom
Note 15: Gain matching =
, nominal at VCC = 3.3V, TA = +25°C.
Gainmodnom / Gainbiasnom
4
Maxim Integrated
MAX3643
155Mbps to 2.5Gbps Burst-Mode Laser Driver
Typical Operating Characteristics
(Typical values are at V
= 3.3V, T = +25°C, data pattern = 27-1 PRBS + 80 ones + 27-1 PRBS + 80 zeros, unless otherwise
A
CC
noted.)
OPTICAL EYE DIAGRAM
OPTICAL EYE DIAGRAM
OPTICAL EYE DIAGRAM
(155.52Mbps, 117MHz FILTER,
(622.08Mbps, 467MHz FILTER,
(1.24416Gbps, 933MHz FILTER,
23
23
23
PATTERN = 2 - 1 PRBS)
PATTERN = 2 - 1 PRBS)
PATTERN = 2 - 1 PRBS)
MAX3643 toc01
MAX3643 toc02
MAX3643 toc03
EXCELIGHT SLT2886-LR LASER
AVERAGE OPTICAL POWER = -6dBm
EXTINCTION RATIO = 15dB
MASK MARGIN = 49%
EXCELIGHT SLT2886-LR LASER
AVERAGE OPTICAL POWER = -6dBm
EXTINCTION RATIO = 15dB
MASK MARGIN = 45%
EXCELIGHT SLT2886-LR LASER
AVERAGE OPTICAL POWER = -6dBm
EXTINCTION RATIO = 14dB
MASK MARGIN = 38%
OPTICAL EYE DIAGRAM
ELECTRICAL EYE DIAGRAM
(2.48832Gbps, 2.3GHz FILTER,
(2.5Gbps, I
PATTERN = PRBS 2 - 1 + 80 CID)
= 30mA,
SUPPLY CURRENT vs. TEMPERATURE
MOD
23
7
PATTERN = 2 - 1 PRBS)
(I
BIAS
= 20mA, I
= 30mA)
MOD
MAX3643 toc04
MAX3643 toc05
60
55
50
45
40
35
30
25
20
15
10
EXCLUDES BIAS AND
MODULATION CURRENT
EXCELIGHT SLT2886-LR LASER
AVERAGE OPTICAL POWER = -6dBm
EXTINCTION RATIO = 10dB
MASK MARGIN = 18%
-40 -20
0
20
40
80
60
100ps/div
TEMPERATURE (°C)
Maxim Integrated
5
MAX3643
155Mbps to 2.5Gbps Burst-Mode Laser Driver
Typical Operating Characteristics (continued)
(Typical values are at V
noted.)
= 3.3V, T = +25°C, data pattern = 27-1 PRBS + 80 ones + 27-1 PRBS + 80 zeros, unless otherwise
A
CC
DETERMINISTIC JITTER
vs. MODULATION AMPLITUDE
RANDOM JITTER
vs. MODULATION AMPLITUDE
30
27
24
21
18
15
12
9
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
6
3
0
60
40 50
(mA)
10
30
50
70 80
10
20
60
70
80
20
40
30
I
(mA)
I
MOD
MOD
I
vs. I
I vs. I
BIAS BIASSET
MOD
MODSET
90
80
70
60
50
40
30
20
10
90
80
70
60
50
40
30
20
10
0
0
0
200
400
600
800
1000
0
200
400
600
800
1000
I
(μA)
I
(μA)
MODSET
BIASSET
BIAS CURRENT MONITOR GAIN
/I ) vs. TEMPERATURE
I
(R
vs. VMSET
MOD
(I
BCMON BIAS
= 1kΩ)
MODSET
90
80
70
60
50
40
30
20
10
0
17
16
15
14
13
12
0
0.2
0.4
0.6
VMSET (V)
0.8
1.0
1.2
-40
-20
0
20
40
60
80
TEMPERATURE (°C)
6
Maxim Integrated
MAX3643
155Mbps to 2.5Gbps Burst-Mode Laser Driver
Typical Operating Characteristics (continued)
(Typical values are at V
= 3.3V, T = +25°C, data pattern = 27-1 PRBS + 80 ones + 27-1 PRBS + 80 zeros, unless otherwise
A
CC
noted.)
I
+ I
CURRENT
BIAS MOD
TIMING DIAGRAM, BURST-ON
(933MHz FILTER ON OUT+)
I
(R
vs. VBSET
BIAS
THRESHOLD vs. R
IMAX
= 1kΩ)
BIASSET
MAX3643 toc15
160
140
120
100
80
90
80
70
60
50
40
30
20
10
0
V
OUT+
V
BIAS+
60
V
BEN+
40
20
0
0
5
10
15
(kΩ)
20
25
30
0
0.2
0.4
0.6
0.8
1.0
500ps/div
R
VBSET (V)
IMAX
SAMPLE/HOLD
(10MΩ LOAD, 2.8μs SAMPLE
AND 100μs HOLD, MDIN = 1.56V)
TIMING DIAGRAM, BURST-OFF
(933MHz FILTER ON OUT+)
MAX3643 toc16
MAX3643 toc17
V
OUT+
1.56V
MDOUT
BEN+
1.22V
V
V
BIAS+
BEN+
500ps/div
20μs/div
Maxim Integrated
7
MAX3643
155Mbps to 2.5Gbps Burst-Mode Laser Driver
Pin Description
PIN
1
NAME
FUNCTION
V
CCA
Analog Supply Voltage
2
IN+
IN-
Noninverted Data Input, LVPECL Compatible
Inverted Data Input, LVPECL Compatible
Signal Supply Voltage
3
4
V
CCS
5
BEN+
Noninverted Burst-Enable Input, LVPECL Compatible
Inverted Burst-Enable Input, LVPECL Compatible
6
BEN-
BENOUT
EN
7
Burst-Enable Output, LVCMOS. Signal replicates BEN input.
Enable Input LVCMOS. Active low enables BIAS and OUT outputs.
8
Bias Current Monitor. Current out of this pin develops a ground-referenced voltage across an
external resistor proportional to the bias current.
9
BCMON
10
11
IMAX
MDOUT
MDIN
Current-Limit Reference. Connect a resistor from IMAX to GND to set maximum I
Monitor Diode Out. Analog Output for sample/hold.
plus I
.
BIAS
MOD
12
Monitor Diode In. Analog Input for sample/hold.
13
BIAS-
Connect BIAS- to V Through a 10ꢀ Resistor and Switching Diode
CC
14
BIAS+
Laser Bias Current Output. Modulation current flows into this pin when BEN input is high.
Output Supply Voltage
15, 18
V
CCO
Laser Modulation Current Output. Modulation current flows into this pin when both BEN and IN
inputs are high.
16
OUT+
17
19
20
21
OUT-
GND
Connect OUT- to Laser Diode Anode Through a 15ꢀ Resistor and Switching Diode
Supply Ground. This pin must be connected to ground.
MODSET
VMSET
Modulation Current Set. Current from this pin to ground sets the laser modulation current.
MODSET Reference. A ground-referenced voltage at this point establishes the MODSET reference.
22
23
24
VREF
VBSET
Reference Voltage Output. May be used for VMSET, VBSET.
BIASSET Reference. A ground-referenced voltage at this point establishes the BIASSET reference.
Bias Current Set. Current from this pin to ground sets the laser bias current.
BIASSET
Exposed Paddle (Ground). The exposed pad must be soldered to the circuit board ground for proper
thermal and electrical operation.
—
EP
8
Maxim Integrated
MAX3643
155Mbps to 2.5Gbps Burst-Mode Laser Driver
V
CC
R
P
L
P
15Ω
OUT+
R
D
MAX3643
OUT-
R
R
D
COMP
IN+
BIAS+
C
COMP
LVPECL
V
CC
10Ω
IN-
BIAS-
BEN+
LVPECL
BEN-
IMAX
CMOS
BENOUT
MDIN
LIMIT
LIMIT
V
CC
V
CC
CMOS
EN
I
M
= 88 x I
I
I
= 88 x I
2
I
I
2
1
B
1
MDOUT
V
CC
= I x
B 0.014
BCMON
1.2V
R
MOD
R
BIAS
VREF
VMSET
VBSET
BIASSET BCMON
MODSET
Figure 1. Functional Diagram
Maxim Integrated
9
MAX3643
155Mbps to 2.5Gbps Burst-Mode Laser Driver
should be close to 15Ω. An RC shunt compensation
Detailed Description
network, R
/C
, connected between the laser
COMP COMP
The MAX3643 laser driver includes a bias current gen-
erator, bias current monitor, modulation current genera-
tor, laser drive outputs, and monitor diode sample and
hold. LVPECL-compatible inputs are provided for both
high-speed data and burst enable. The high-speed
burst-enable input signal is replicated on an LVCMOS
output for use by the controller.
diode cathode and ground should also be provided to
reduce optical output aberrations and duty-cycle dis-
tortion caused by laser diode parasitic inductance. The
values of R
and C
can be adjusted to match
COMP
COMP
the laser diode and PCB layout characteristics for opti-
mal optical eye performance (refer to Application
Note 274: HFAN-02.0: Interfacing Maxim Laser Drivers
with Laser Diodes). The OUT- pin is connected through
a 15Ω resistor and switching diode to the laser diode
anode. The switching diode at OUT- improves the opti-
cal output eye and burst-enable delay by better match-
ing the laser diode characteristics.
Laser Diode Modulation and
Bias Current Generators
Laser diode modulation current amplitude is controlled
by the current out of the MODSET pin, and bias current
by the current out of the BIASSET pin, according to:
For data rates greater than 1Gbps, a parallel RL peak-
I
= I
= I
x 88
x 88
MOD
MODSET
BIASSET
ing network, R /L , connected between the laser diode
P
CC
P
I
BIAS
anode and V
is recommended. This network creates
A voltage source and two op amps are provided to
enable I and I to be set using either a
resistor to ground or a current digital-to-analog convert-
er (DAC). The high-impedance op amp reference input
can be externally controlled, so that the modulation and
bias currents can also be set using voltage DACs.
a differential drive for the laser diode to improve rise/fall
times and reduce jitter. The values of R and L are
MODSET
BIASSET
P
P
also adjusted to match the laser diode and PCB layout
characteristics for optimal optical eye performance.
The bias current ranges from 1mA to 70mA, as set by
the current through BIASSET. Current in the BIAS out-
put switches at high speed when bursting; therefore,
the BIAS+ pin should be connected directly through a
Laser Diode Modulation and
Bias Current Limiter
resistor, equal to R as determined above, to the laser
D
Typical laser diodes have an absolute maximum rating
of 150mA. To reduce the possibility of laser damage,
the modulation current and bias current are shut off if
cathode. The BIAS- pin is connected through a 10Ω
resistor and switching diode to V
.
CC
the sum I
+ I
attempts to exceed the limit set
BIAS
MOD
When the BEN input is high, the laser driver sinks bias
and modulation current according to the settings at
MODSET and BIASSET. When the BEN input is low, the
BIAS+ and OUT+ currents both shut off within 2ns.
Note that when BEN is low, the bias current is shunted
through the BIAS- output and the modulation current
through the OUT- output.
by R
; see the Typical Operating Characteristics.
IMAX
Bias Current Monitor
The laser diode bias current can be monitored by measur-
ing the voltage across an external load resistor connected
from BCMON to ground. For example, a 1kΩ resistor from
BCMON to ground gives the following relationship:
Monitor Diode Sample and Hold
Laser monitor diode current is only generated when
there is an optical output (BEN is active). When BEN is
inactive, the monitor current is zero, reflecting the fact
that the laser is off. A sample-and-hold circuit, trig-
gered by the state of the BEN input, is provided in the
MAX3643. During the burst-enable active period, the
voltage present at MDIN is stored on an internal sam-
ple-and-hold capacitor; and during the burst-enable
inactive period, that voltage is output on MDOUT; see
the timing diagram in Figure 2.
V
= I
× G
×1kΩ
BCMON BIAS
BSM
The voltage at BCMON must be below 1.4V for proper
operation.
Output Drivers
The modulation current ranges from 10mA to 85mA, as
set by the current through MODSET. The laser modula-
tion current output OUT+ is optimized to drive a 15Ω
load, and must be DC-coupled. A series damping resis-
tor, R , provides impedance matching to the laser
D
diode. The combined value of the series damping resis-
tor and the laser diode equivalent series resistance
While the internal sample-and-hold is sampling (BEN
active), MDOUT voltage takes a 1.2V reference level.
10
Maxim Integrated
MAX3643
155Mbps to 2.5Gbps Burst-Mode Laser Driver
BURST-ENABLE (BEN ) IN
≤ 125μs FOR BPON/GPON
INTERNAL MDIN VOLTAGE SAMPLER
BENOUT OUTPUT
3μs
MDOUT
< 2.56mV
1.2V
100μs
Figure 2. Sample-and-Hold Timing Diagram
I
= I
x 88
Enable Input
An LVCMOS input, EN, is provided to disable both bias
and modulation currents under external control. The
maximum time to disable laser current with the EN con-
trol is 375ns.
MOD
MODSET
To program the laser modulation current using a resis-
tor or digital potentiometer, connect VMSET to VREF,
attach a resistor from the MODSET pin to ground, and
set the current according to:
Setting the Current Limit
A current limiter is provided to protect the laser diode
by shutting down both bias and modulation currents
when total current exceeds a value set by the resistor
connected from IMAX to ground. Do not use less than
1.2V
I
=
× 88
MOD
R
+R
MOD
MODSET
To program the laser modulation current using a PWM
voltage DAC (requiring a high-impedance load), attach
a DAC output to the VMSET pin, connect a resistor from
the MODSET pin to ground as shown in the Typical
Applications Circuit, and set the current according to:
3kΩ R
. See the I
+ I
Current Threshold vs.
MAX
BIAS
MOD
I
R
graph in the Typical Operating Characteristics.
IMAX
Programming the MODSET and
BIASSET Inputs
To program the laser modulation current using a cur-
rent DAC, connect VMSET to VREF, attach the DAC to
the MODSET pin and set the current according to:
V
DAC
I
=
× 88
MOD
R
+R
MODSET
MOD
Maxim Integrated
11
MAX3643
155Mbps to 2.5Gbps Burst-Mode Laser Driver
This approach can also be used for a conventional volt-
V
CC
age DAC output, if desired. In all cases, the voltage at
MODSET must be kept ≤ 1.4V, which limits the range of
acceptable values for R
depending on the maxi-
MODSET
mum modulation current.
MAX3643
130Ω
82Ω
130Ω
82Ω
Laser diode bias current is set in the same manner as
modulation current.
Z
Z
= 50Ω
= 50Ω
IN+/BEN+
IN-/BEN-
O
LVPECL
LVPECL Data/Burst-Enable Inputs
The MAX3643 data and BEN inputs are biased with an
on-chip, high-impedance network. When DC-coupled,
the MAX3643 operates properly with signals that meet
the EC table input-swing and common-mode require-
ments, including LVPECL and most CML.
O
See Figure 3 for a termination network that can be used
to connect the data and BEN inputs to LVPECL data out-
puts. Other termination networks may also be used, as
long as both the input swing and common limits are met.
Figure 3. LVPECL High-Speed Inputs
Sample-and-Hold Operation
When the MAX3643 internal sample-and-hold is not
required, the MDIN pin should be connected to ground
and the MDOUT pin unconnected. If the internal sample-
and-hold is required, then it is necessary to ensure that
the time constant resulting from the monitor diode load
resistance and the total load capacitance is compatible
with the desired minimum burst interval. It is also neces-
sary to make certain that the load at MDOUT does not
exceed the capability of the MDOUT pin.
IN+
IN-
V
V
+ (100mV to 800mV)
- (100mV to 800mV)
CMBEN
CMBEN
BEN+
V
CMBEN
3.3V
BEN-
R = 1.65kΩ
1
MAX3643
Because the voltage at MDIN is not reflected to MDOUT
until after the end of the laser burst, systems using the
internal sample-and-hold alone cannot support continu-
ous mode operation, often a required feature for module
calibration. In this case, the voltage at MDIN can also
be connected directly to a controller mux input. As long
as the total capacitance (including monitor diode intrin-
sic capacitance, MDIN capacitance, mux off-capaci-
tance, and wiring parasitics) is less than 50pF, and the
monitor diode load resistor is less than 2kΩ, then the
sample-and-hold captures a 576ns minimum burst. The
MAX3643 typical MDIN capacitance is 5pF, typical
monitor diode maximum capacitance is 25pF, and the
typical capacitance of a mux input in the off-state is
3pF to 5pF. When the mux is in the on-state, the capac-
itance at the input is typically 10pF to 20pF.
V
= +2.0V
CMBEN
R = 2.54kΩ
2
Figure 4. Single-Ended Biasing for Burst Enable
If the minimum burst duration is longer than 576ns, it
may be useful to connect an external capacitor in par-
allel with the monitor diode load to limit the effects of
the data pattern on the monitor diode output.
12
Maxim Integrated
MAX3643
155Mbps to 2.5Gbps Burst-Mode Laser Driver
Applications Information
IN+
Running Burst-Enable Single-Ended
See Figure 5 for setting up the single-ended LVTTL or
LVCMOS biasing for burst enable.
V
CC
IN-
R = 5kΩ
3
LVTTL OR LVCMOS HIGH
LVTTL OR LVCMOS LOW
Layout Considerations
To minimize inductance, keep the connections
between the MAX3643 output pins and laser diode as
close as possible. Place a bypass capacitor as close
BEN+
R = 3kΩ
4
V
CC
BEN-
as possible to each V
connection. Take extra care
CC
R = 5kΩ
5
to minimize stray parasitic capacitance on the BIAS
and MDIN pins. Use good high-frequency layout tech-
niques and multilayer boards with uninterrupted
ground planes to minimize EMI and crosstalk.
MAX3643
R = 9kΩ
6
Laser Safety and IEC 825
Using the MAX3643 laser driver alone does not ensure
that a transmitter design is compliant with IEC 825. The
entire transmitter circuit and component selections must
be considered. Each user must determine the level of
fault tolerance required by the application, recognizing
that Maxim products are neither designed nor authorized
for use as components in systems intended for surgical
implant into the body, for applications intended to sup-
port or sustain life, or for any other application in which
the failure of a Maxim product could create a situation
where personal injury or death can occur.
Figure 5. Single-Ended LVCMOS or LVTTL Biasing for Burst
Enable
Interface Model
V
CC
V
CC
V
CC
16kΩ
Exposed-Paddle Package
The exposed paddle on the 24-pin TQFN provides a
very low thermal resistance path for heat removal from
the IC. The pad is also electrical ground on the
MAX3643 and must be soldered to the circuit board
ground for proper thermal and electrical performance.
Refer to Maxim Application Note 862: HFAN-08.1:
Thermal Considerations of QFN and Other Exposed-
Paddle Packages for additional information.
5kΩ
5kΩ
IN+/BEN+
V
CC
IN-/BEN-
24kΩ
MAX3643
Figure 6. Simplified Input Circuit Schematic
Maxim Integrated
13
MAX3643
155Mbps to 2.5Gbps Burst-Mode Laser Driver
Pin Configuration
Chip Information
TRANSISTOR COUNT: 2771
TOP VIEW
PROCESS: SiGe BiPOLAR
Package Information
18 17 16 15 14 13
For the latest package outline information and land patterns,
go to www.maximintegrated.com/packages. Note that a “+”,
“#”, or “-” in the package code indicates RoHS status only.
Package drawings may show a different suffix character, but
the drawing pertains to the package regardless of RoHS status.
19
12
GND
MDIN
MODSET 20
11 MDOUT
21
22
23
24
10
9
VMSET
VREF
IMAX
MAX3643
BCMON
PACKAGE
TYPE
PACKAGE
CODE
OUTLINE
NO.
LAND
PATTERN NO.
VBSET
EN
8
*EP
24 TQFN-EP
T2444-3
21-0139
90-0021
BIASSET
BENOUT
7
+
1
2
3
4
5
6
THIN QFN (4mm x 4mm)
*THE EXPOSED PAD MUST BE CONNECTED TO GROUND FOR PROPER
THERMAL AND ELECTRICAL PERFORMANCE.
14
Maxim Integrated
MAX3643
155Mbps to 2.5Gbps Burst-Mode Laser Driver
Revision History
REVISION REVISION
PAGES
CHANGED
DESCRIPTION
NUMBER
DATE
0
11/05
Initial release.
—
All
1
Added “155Mbps to 2.5Gbps” to the data sheet/part title.
Updated the Applications section.
1
2
10/08
7/10
In the Operating Conditions table, changed the data rate from 1250Mbps to 2500Mbps.
In the Typical Operating Characteristics, added the Electrical Eye Diagram graph.
2
6
Replaced the Typical Application Circuit; added the soldering temperature to the Absolute
Maximum Ratings section; updated the optical eye mask margins in the Electrical
Characteristics table; corrected equation in Note 14; added the optical eye diagrams to
the Typical Operating Characteristics section; updated the pin descriptions for the pins
with diodes (13, 17) in the Pin Description table; updated Figure 1; updated the Output
Drivers section; updated the Layout Considerations section; added the land pattern
number to the Package Information table.
1, 2, 4–10,
12, 13, 14
Updated Typical Application Circuit, Electrical Characteristics table, and Typical
Operating Characteristics global conditions, and added bias current overshoot parameter
3
4
5/12
1–7
4
12/12
Updated Note 1 in the Electrical Characteristics
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent
licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and
max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated 160 Rio Robles, San Jose, CA 95134 USA 1-408-601-1000
15
© 2012 Maxim Integrated Products, Inc.
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
相关型号：
MAX3645EEE
+2.97V to +5.5V, 125Mbps to 200Mbps Limiting Amplifier with Loss-of-Signal Detector
MAXIM
MAX3645EEE+T
Support Circuit, 1-Func, Bipolar, PDSO16, 0.150 INCH, 0.025 INCH PITCH, MO-137, QSOP-16
MAXIM
MAX3645EEE-T
Support Circuit, 1-Func, Bipolar, PDSO16, 0.150 INCH, 0.025 INCH PITCH, MO-137AB, QSOP-16
MAXIM
MAX3645ESE
+2.97V to +5.5V, 125Mbps to 200Mbps Limiting Amplifier with Loss-of-Signal Detector
MAXIM
©2020 ICPDF网 联系我们和版权申明