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PDF MAX3273 Data sheet ( Hoja de datos )
| Número de pieza | MAX3273 | |
| Descripción | +3.3V / 2.5Gbps Low-Power Laser Driver | |
| Fabricantes | Maxim Integrated | |
| Logotipo |  |
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19-2081; Rev 3; 2/07
+3.3V, 2.5Gbps Low-Power Laser Driver
General Description
The MAX3273 is a compact, low-power laser driver for
applications up to 2.7Gbps. The device uses a single
+3.3V supply and typically consumes 30mA. The bias
and modulation current levels are programmed by
external resistors. An automatic power-control (APC)
loop is incorporated to maintain a constant average
optical power over temperature and lifetime. The laser
driver is fabricated using Maxim’s in-house, second-
generation SiGe process.
The MAX3273 accepts differential CML-compatible
clock and data input signals. Inputs are self-biased to
allow AC-coupling. An input data-retiming latch can be
enabled to reject input jitter if a clock signal is available.
The driver can provide bias current up to 100mA and
modulation current up to 60mAP-P with typical (20% to
80%) edge speeds of 59ps. A failure-monitor output is
provided to indicate when the APC loop is unable to
maintain average optical power. The MAX3273 is avail-
able in 4mm ✕ 4mm, 24-pin QFN and thin QFN pack-
ages, as well as in die form.
Applications
SONET OC-48 and SDH STM-16
Transmission Systems
Add/Drop Multiplexers
Digital Cross-Connects
2.5Gbps Optical Transmitters
Pin Configurations appear at end of data sheet.
Features
♦ 30mA Power-Supply Current
♦ Single +3.3V Power Supply
♦ Up to 2.7Gbps (NRZ) Operation
♦ Automatic Average Power Control with Failure
Monitor
♦ Programmable Modulation Current from 5mA to
60mA
♦ Programmable Bias Current from 1mA to 100mA
♦ Typical Fall Time of 59ps
♦ Selectable Data Retiming Latch
♦ Complies with ANSI, ITU, and Bellcore
SDH/SONET Specifications
Ordering Information
PART
TEMP RANGE PIN-
PACKAGE
PACKAGE
CODE
MAX3273EGG
-40°C to +85°C
24 QFN
(4mm 4mm)
G2444-1
MAX3273ETG+ -40°C to +85°C
24 Thin QFN
(4mm 4mm)
T2444-2
MAX3273E/D -40°C to +85°C Dice*
—
*Dice are designed to operate from TA = -40°C to +85°C, but
are tested and guaranteed at TA = +25°C only.
+Denotes lead-free package.
Typical Application Circuit
DATA +
DATA -
2.5Gbps
SERIALIZER
WITH CLOCK
GENERATION
CLK+
CLK-
50Ω
100Ω
50Ω
50Ω
100Ω
50Ω
VCC
DATA +
DATA -
CLK+
0.01μF
VCC
LP1
OUT-
25Ω
MAX3273
OUT+
BIAS
25Ω
LP1
LP2
20Ω
0.056μF
CLK- MD
500pF
REPRESENTS A CONTROLLED-IMPEDANCE TRANSMISSION LINE.
†.
________________________________________________________________ Maxim Integrated Products 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.
1 page  
+3.3V, 2.5Gbps Low-Power Laser Driver
(VCC = 3.3V, TA = +25°C, unless otherwise noted.)
ELECTRICAL EYE DIAGRAM
(IMOD = 20mA, 213 - 1 80CID)
Typical Operating Characteristics
ELECTRICAL EYE DIAGRAM
(IMOD = 60mA, 213 - 1 80CID)
125mV/div
400mV/div
60ps/div
60ps/div
OPTICAL EYE DIAGRAM
(2.488Gbps, 1300nm FP LASER,
1.87GHz FILTER)
57ps/div
MITSUBISHI ML725C8F
LASER DIODE
140
120
100
80
60
40
20
0
0.1
IBIASMAX vs. RBIASMAX
1 10 100
RBIASMAX (kΩ)
1000
90
80
70
60
50
40
30
20
10
0
0.1
IMOD vs. RMODSET
1 10
RMODSET (kΩ)
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
0.1
IMD vs. RAPCSET
1 10
RAPCSET (kΩ)
100
SUPPLY CURRENT vs. TEMPERATURE
100
90 EXCLUDE IBIAS, IMOD
25Ω LOAD
80
70
60
50
40
30
20
10
0
-40 -15 10 35 60
TEMPERATURE (°C)
85
100
_______________________________________________________________________________________ 5
5 Page 
+3.3V, 2.5Gbps Low-Power Laser Driver
Table 1. Optical Power Relations
PARAMETER
Average Power
SYMBOL
PAVG
RELATION
PAVG = (P0 + P1) / 2
Extinction Ratio
re
re = P1 / P0
Optical Power of a 1
P1
P1 = 2PAVGre / (re + 1)
Optical Power of a 0
P0
P0 = 2PAVG / (re + 1)
Optical Amplitude
PP-P
PP-P = P1 - P0 = 2PAVG(re - 1) / (re + 1)
Laser Slope Efficiency
η
η = PP-P / IMOD
Modulation Current
IMOD
IMOD = PP-P / η
Threshold Current
ITH
P0 at 1 ≥ ITH
Bias Current
IBIAS
IBIAS ≥ ITH + IMOD / 2
Laser-to-Monitor Transfer
ρMON
IMD / PAVG
Note: Assuming a 50% average input duty cycle and mark density.
Applications Information
An example of how to set up the MAX3273 follows.
Select Laser
A communication-grade laser should be selected for
2.5Gbps/2.7Gbps applications. Assume the laser out-
put average power is PAVG = 0, the minimum extinction
ratio is re = 6.6 (8.2dB), the operating temperature is
-40°C to +85°C, and the laser diode has the following
characteristics:
• Wavelength: λ = 1310nm
• Threshold Current: ITH = 22mA at +25°C
• Threshold Temperature Coefficient: βTH = 1.3%/°C
• Laser-to-Monitor Transfer: ρMON = 0.2A/W
• Laser Slope Efficiency: η = 0.05mW/mA at +25°C
Determine RAPCSET
The desired monitor diode current is estimated by IMD
= PAVG × ρMON = 200µA. The IMD vs. RAPCSET graph
in the Typical Operating Characteristics shows that
RAPCSET should be 7.5kΩ.
Determine RMODSET
To achieve a minimum extinction ratio (re) of 6.6 over
temperature and lifetime, calculate the required extinc-
tion ratio at +25°C. Assuming re = 20, the peak-to-peak
optical power PP-P = 1.81mW, according to Table 1.
The required modulation current is 1.81mW/
(0.05mW/mA) = 36.2mA. The IMOD vs. RMODSET graph
in the Typical Operating Characteristics shows that
RMODSET should be 5kΩ.
Determine RBIASMAX
Calculate the maximum threshold current (ITH(MAX)) at
TA = +85°C and end of life. Assuming ITH(MAX) =
50mA, the maximum bias current should be: IBIASMAX
= ITH(MAX) + (IMOD / 2). In this example, IBIASMAX =
68.1mA. The IBIASMAX vs. RBIASMAX graph in the
Typical Operating Characteristics shows that RBIASMAX
should be 3.5kΩ.
______________________________________________________________________________________ 11
11 Page | ||
| Páginas | Total 18 Páginas | |
| PDF Descargar | [ Datasheet MAX3273.PDF ] | |
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