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參數(shù)資料
| 型號： | MAX3766 |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | Quad LVDS Transmitter with Flow-Through Pinout 16-TSSOP -40 to 85 |
| 中文描述： | 622Mbps、LAN/WAN激光驅(qū)動器，帶有自動功率控制及安全關(guān)斷 |
| 文件頁數(shù)： | 12/20頁 |
| 文件大?。?/td> | 250K |
| 代理商： | MAX3766 |
M
S et Modulation-Current T empc o
Compute the required modulation tempco from the
slope efficiency of the laser at T
A
= +25°C and at a hot
temperature. Then select the value of R
TC
from the
Typical Operating Characteristics.
For example, suppose a laser has a slope efficiency
(SE) of 0.021mW/mA at +25°C, which reduces to
0.018mW/mA at +85°C. The temperature coefficient is
given by the following:
(
From the Typical Operating Characteristics, the value
for R
TC
, which offsets the tempco of the laser, is 3k
. If
modulation temperature compensation is not desired,
connect TC directly to REF1.
S et Modulation Current
The modulation-current amplitude can be programmed
with a fixed resistor or adjusted with a potentiometer. A
small internal resistance is provided to prevent damage
if the potentiometer is adjusted to the end of its range.
The value of R
MOD
can be selected from the Typical
Operating Characteristics.
Example: A transmitter requires average power of
-8dBm (160μW), with an extinction ratio of 15. The opti-
cal signal output is 280μW (see Optical Power
Relations). If the slope efficiency is 0.021mW/mA at
+25°C , then the required modulation current is
0.280mW / 0.021mW/mA = 13.3mA. From the Typical
Operating Characteristics, the value of R
MOD
is select-
ed to be 3k
.
S et Average Laser Power
and Maximum Bias Current
When APC is used, the average power control is pro-
grammed by R
POWERSET
, which is typically a poten-
tiometer. The value of R
POWERSET
can be estimated
from the Typical Operating Characteristics.
Example: Suppose a transmitter’s output power will be
adjusted to -8dBm (160μW) average power during
manufacturing. The coupling efficiency from laser to
monitor photodiode varies from 0.4A/W to 0.8A/W for
the selected laser, causing monitor current to vary
between 64μA and 128μA. From the Typical Operating
Characteristics, R
POWERSET
should be adjustable
between 12k
and 24k
.
Select R
BIASMAX
to provide sufficient current for a hot
laser at its end of life. For example, if the expected
laser threshold at +85°C and end of life is 40mA, then
from the Typical Operating Characteristics, R
BIASMAX
should be 1k
or less.
If APC is not used, the laser bias current is pro-
grammed by R
BIASMAX
. Select R
BIASMAX
from the
Typical Operating Characteristics.
S et APC T ime Constant
Capacitor C
MD
determines the APC time constant, and
must be large enough not to cause data-dependent jit-
ter. For 622Mbps SONET/ATM applications, Maxim rec-
ommends selecting C
MD
≥
0.1μF.
S elec t C
S AFET Y
When using the latched shutdown configuration, deter-
mine the minimum value of C
SAFETY
from the Typical
Operating Characteristics. Calculate C
SAFETY
as follows:
For example: If C
MD
is 0.1μF and typical monitor cur-
rent (I
MD
) is 100μA, then the value of C
SAFETY
should
be 50nF or larger. This ensures that t
SAFETY
is at least
10 times the t
APC
.
Design Bias Filter
To reduce data-dependent jitter, add a filter at BIAS
(see Typical Operating Circuit. Maxim recommends a
1μH inductor or ferrite bead with a self-resonance fre-
quency of 200MHz or more.
Design Laser-Compensation
Filter Network
Laser package lead inductance causes the laser
impedance to increase at high frequencies, which
leads to ringing, overshoot, and degradation of the out-
put eye. A laser-compensation filter network can be
used to reduce the output load seen by the MAX3766
at high frequencies, thereby reducing output ringing
and overshoot.
The compensation components (R
COMP
and C
COMP
)
are most easily determined by experimentation. Begin
with a no-compensation network, and observe the ring
frequency (f
n
) of the laser and laser driver (Figure 7).
Begin with R
COMP
= 25
and C
COMP
= 1/(2
π
f
n
R
COMP
).
Increase C
COMP
until the desired transmitter eye is
obtained.
C
SAFETY
=
C
20k I
MD
MD
Laser tempco
SE
SE
SE
85
25
10
85
25
25
=
)
)
=
2380ppm C
/
622Mbps LAN/WAN Laser Driver with
Automatic Power Control and S afety S hutdown
12
______________________________________________________________________________________
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| MAX3766E/D | 功能描述:激光驅(qū)動器 RoHS:否 制造商:Micrel 數(shù)據(jù)速率:4.25 Gbps 工作電源電壓:3 V to 3.6 V 電源電流:80 mA 最大工作溫度:+ 85 C 封裝 / 箱體:QFN-16 封裝:Tube |
| MAX3766E/D DIE | 制造商:Maxim Integrated Products 功能描述: |
| MAX3766EEP | 功能描述:激光驅(qū)動器 622Mbps LAN/WAN RoHS:否 制造商:Micrel 數(shù)據(jù)速率:4.25 Gbps 工作電源電壓:3 V to 3.6 V 電源電流:80 mA 最大工作溫度:+ 85 C 封裝 / 箱體:QFN-16 封裝:Tube |
| MAX3766EEP+ | 功能描述:激光驅(qū)動器 622Mbps LAN/WAN RoHS:否 制造商:Micrel 數(shù)據(jù)速率:4.25 Gbps 工作電源電壓:3 V to 3.6 V 電源電流:80 mA 最大工作溫度:+ 85 C 封裝 / 箱體:QFN-16 封裝:Tube |
| MAX3766EEP+T | 功能描述:激光驅(qū)動器 622Mbps LAN/WAN RoHS:否 制造商:Micrel 數(shù)據(jù)速率:4.25 Gbps 工作電源電壓:3 V to 3.6 V 電源電流:80 mA 最大工作溫度:+ 85 C 封裝 / 箱體:QFN-16 封裝:Tube |
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