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參數(shù)資料
| 型號： | MAX3262 |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | 32-Bit Digital Signal Controller with Flash 100-LQFP -40 to 85 |
| 中文描述： | 1Gbps、高速限幅放大器，帶有無抖動的信號消失檢測 |
| 文件頁數(shù)： | 9/12頁 |
| 文件大?。?/td> | 145K |
| 代理商： | MAX3262 |
heat. Fortunately, a substantial portion of this power is
dissipated across the laser diode. A typical laser diode
drops approximately 1.6V when forward biased. This
leaves 3.4V at the MAX3263’s OUT- terminal. It is safe to
reduce the output terminal voltage even further with a
series damping resistor. Terminal voltage levels down to
2.2V can be used without degrading the laser driver’s
high-frequency performance. Power dissipation can be
further reduced by adding a series resistor on the laser
driver’s OUT+ side. Select the series resistor so the
OUT+ terminal voltage does not drop below 2.2V with the
maximum modulation current.
_____________Applications Information
Programming the MAX3263 Laser Driver
Programming the MAX3263 is best explained by an
example. Assume the following laser diode characteris-
tics:
Wavelength
λ
Threshold Current
I
TH
1300nm
20mA at +25°C(+0.35mA/
°C temperature variation)
0.1A/W (monitor current /
average optical power
into the fiber)
0.1mW/mA (worst case)
Monitor Responsivity
ρ
mon
Modulation Efficiency
η
Now assume the communications system has the fol-
lowing requirements:
Average Power
Extinction Ratio
Temperature Range
1) Determine the value of IPINSET:
The desired monitor-diode current is (P
AVE
)(
ρ
mon
) =
(1mW)(0.1A/W) = 100μA. The R
PINSET
vs. Monitor
Current graph in the Typical Operating Characteristics
show that R
PINSET
should be 18k
.
2) Determine R
MODSET
:
The average power is defined as (P1 + P0) / 2, where
P1 is the average amplitude of a transmitted “one” and
P0 is the average amplitude of a transmitted “zero.”
The extinction ratio is P1/P0. Combining these equa-
tions results in P1 = (2 x P
AVE
x Er) / (Er + 1) and P0 =
(2 x P
AVE
) / (Er + 1). In this example, P1 = 1.6mW and
P0 = 0.4mW. The optical modulation is 1.2mW. The
modulation current required to produce this output is
1.2mW /
η
= (1.2mW) / (0.1mA/mW) = 12mA. The
Typical Operating Characteristics show that R
MODSET
= 3.9k
yields the desired modulation current.
3) Determine the value of R
OSADJ
:
Using the Allowable R
OSADJ
Range vs. Modulation
Current graph in the Typical Operating Characteristics
a 5.6k
resistor is chosen for 12mA of modulation cur-
rent. The maximum R
OSADJ
values given in the graph
minimize aberrations in the waveform and ensure that
the driver stage operates fully limited.
4) Determine the value of R
BIASSET
:
The automatic power control circuit can adjust the bias
current 40mA from the initial setpoint. This feature
makes the laser driver circuit reasonably insensitive to
variations of laser threshold from lot to lot. The bias set-
ting can be determined using one of two methods:
A) Set the bias at the laser threshold.
B) Set the bias at the midpoint of the highest and low-
est expected threshold values.
Method A is straightforward. In the second method, it is
assumed that the laser threshold will increase with age.
The lowest threshold current occurs at 0°C when the
laser is new. The highest threshold current occurs at
+70°C at the end of the product’s life. Assume the laser
is near the end of life when its threshold reaches two-
times its original value.
Lowest Bias Current:
I
TH
+
I
TH
= 20mA + (0.35mA/°C)(-25°C) = 11.25mA
Highest Bias Current:
2 x I
TH
+
I
TH
= 40mA + (0.35mA/°C)(+45°C) = 55.8mA
P
AVE
Er
Tr
0dBm (1mW)
6dB (Er = 4)
0°C to +70°C
M
Single +5V, Fully Integrated,
155Mbps Laser Diode Driver
_______________________________________________________________________________________
9
MAX3263
+5V
OUT+
OUT-
IPIN
≥
0.1
μ
F
IBIASOUT
25
18
18
FERRITE
BEAD
LASER
SHUNT RC
PHOTO-
DIODE
0.01
μ
F
AS CLOSE TO THE
LASER ANODE AS
POSSIBLE
AS CLOSE TO THE
LASER CATHODE AS
POSSIBLE
C
10
μ
H
Figure 5. Typical Laser Interface with Bias Compensation
相關PDF資料 |
PDF描述 |
|---|---|
| MAX3263 | 32-Bit Digital Signal Controller with Flash 100-LQFP -40 to 125 |
| MAX3263CAG | Single +5V, Fully Integrated, 155Mbps Laser Diode Driver |
| MAX3270 | 32-Bit Digital Signal Controller with Flash 100-BGA MICROSTAR -40 to 85 |
| MAX3270EMH | 32-Bit Digital Signal Controller with Flash 100-BGA MICROSTAR -40 to 125 |
| MAX3272 | +3.3V, 2.5Gbps Low-Power Limiting Amplifier |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| MAX3262C/D DIE | 制造商:Maxim Integrated Products 功能描述: |
| MAX3262CAG | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
| MAX3263CAG | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
| MAX3263CAG+ | 制造商:Maxim Integrated Products 功能描述:SEMICONDUCTOR |
| MAX3263EVKIT | 功能描述:電源管理IC開發(fā)工具 RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
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