参数资料
| 型号： | MAX3766EEP+T |
| 厂商： | Maxim Integrated |
| 文件页数： | 12/20页 |
| 文件大小： | 0K |
| 描述： | IC LASR DRVR 622MBPS 5.5V 20QSOP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 类型： | 激光二极管驱动器（光纤） |
| 数据速率： | 622Mbps |
| 通道数： | 1 |
| 电源电压： | 4.5 V ~ 5.5 V |
| 电流 - 电源： | 25mA |
| 电流 - 调制： | 60mA |
| 电流 - 偏置： | 80mA |
| 工作温度： | -40°C ~ 85°C |
| 封装/外壳： | 20-SSOP（0.154"，3.90mm 宽） |
| 供应商设备封装： | 20-QSOP |
| 包装： | 带卷 (TR) |
| 安装类型： | 表面贴装 |
622Mbps LAN/WAN Laser Driver with
Automatic Power Control and Safety Shutdown
Set Modulation-Current Tempco
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
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 .
( SE 85 ? SE 25 )
(
)
given by the following:
Laser tempco =
SE 25 ? 85 ? 25
= ? 2380ppm / ° C
? 10 6
Set APC Time 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.
C SAFETY =
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.
Set 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 ? .
Set 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 C SAFETY
When using the latched shutdown configuration, deter-
mine the minimum value of C SAFETY from the Typical
Operating Characteristics . Calculate C SAFETY as follows:
C MD
20k ? ? I MD
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.
12
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相关代理商/技术参数 |
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| MAX3766EVKIT | 功能描述:激光驱动器 Evaluation Kit for the MAX3766 RoHS:否 制造商:Micrel 数据速率:4.25 Gbps 工作电源电压:3 V to 3.6 V 电源电流:80 mA 最大工作温度:+ 85 C 封装 / 箱体:QFN-16 封装:Tube |
| MAX3768C/D | 功能描述:限幅放大器 RoHS:否 制造商:Micrel 输入电压范围（最大值）:3.6 V 工作电源电压:3.3 V 电源电流:40 mA 工作温度范围:- 40 C to + 85 C 封装 / 箱体:MSOP-10 封装:Tube |
| MAX3768CUB | 功能描述:限幅放大器 3-5.5V 1.25/2.5Gbps RoHS:否 制造商:Micrel 输入电压范围（最大值）:3.6 V 工作电源电压:3.3 V 电源电流:40 mA 工作温度范围:- 40 C to + 85 C 封装 / 箱体:MSOP-10 封装:Tube |
| MAX3768CUB+ | 功能描述:限幅放大器 3-5.5V 1.25/2.5Gbps RoHS:否 制造商:Micrel 输入电压范围（最大值）:3.6 V 工作电源电压:3.3 V 电源电流:40 mA 工作温度范围:- 40 C to + 85 C 封装 / 箱体:MSOP-10 封装:Tube |
| MAX3768CUB+T | 功能描述:限幅放大器 3-5.5V 1.25/2.5Gbps RoHS:否 制造商:Micrel 输入电压范围（最大值）:3.6 V 工作电源电压:3.3 V 电源电流:40 mA 工作温度范围:- 40 C to + 85 C 封装 / 箱体:MSOP-10 封装:Tube |
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