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参数资料
| 型号： | MAX3738ETG+ |
| 厂商： | Maxim Integrated |
| 文件页数： | 12/16页 |
| 文件大小： | 0K |
| 描述： | IC LASER DRIVER 4.25GBPS 24TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 75 |
| 类型： | 激光二极管驱动器（光纤） |
| 数据速率： | 4.25Gbps |
| 通道数： | 1 |
| 电源电压： | 2.97 V ~ 3.63 V |
| 电流 - 电源： | 47mA |
| 电流 - 调制： | 85mA |
| 电流 - 偏置： | 100mA |
| 工作温度： | -40°C ~ 85°C |
| 封装/外壳： | 24-WFQFN 裸露焊盘 |
| 供应商设备封装： | 24-TQFN-EP（4x4） |
| 包装： | 管件 |
| 安装类型： | 表面贴装 |
| 产品目录页面： | 1423 (CN2011-ZH PDF) |
155Mbps to 4.25Gbps SFF/SFP Laser Driver
with Extinction Ratio Control
Table 3. Optical Power Relations
The laser driver automatically adjusts the bias to main-
tain the constant average power. For DC-coupled
PARAMETER
Average Power
Extinction Ratio
Optical Power of a One
Optical Power of a Zero
Optical Amplitude
Laser Slope Efficiency
Modulation Current
Threshold Current
Bias Current
(AC-Coupled)
Laser to Monitor
Transfer
SYMBOL
P AVG
r e
P 1
P 0
P P-P
I MOD
I TH
I BIAS
MON
RELATION
P AVG = (P 0 + P 1 ) / 2
r e = P 1 / P 0
P 1 = 2P AVG x r e / (r e + 1)
P 0 = 2P AVG / (r e + 1)
P P-P = P 1 - P 0
= P P-P / I MOD
I MOD = P P-P /
P 0 at I I TH
I BIAS I TH + I MOD / 2
I MD / P AVG
laser diodes:
I AVG = I BIAS + I MOD / 2
Programming the Modulation Current with
Compensation
Determine the modulation current from the laser slope
efficiency:
I MOD = 2 x P AVG / η x (r e - 1) / (r e + 1)
The modulation current of the MAX3738 consists of a
static modulation current (I MODS ), a current proportion-
al to I BIAS , and a current proportional to temperature.
The portion of I MOD set by MODSET is established by
an internal current regulator, which maintains the refer-
ence voltage of V REF across the external programming
resistor. See the Modulation Current vs. R MODSET
Note: Assuming a 50% average input duty cycle and mark
density.
Design Procedure
When designing a laser transmitter, the optical output is
usually expressed in terms of average power and
extinction ratio. Table 3 shows relationships that are
helpful in converting between the optical average
power and the modulation current. These relationships
are valid if the mark density and duty cycle of the opti-
cal waveform are 50%.
For a desired laser average optical power (P AVG ) and
optical extinction ratio (r e ), the required bias and modu-
lation currents can be calculated using the equations in
Table 3. Proper setting of these currents requires
knowledge of the laser to monitor transfer ( ρ MON ) and
slope efficiency ( η ).
Programming the Monitor-Diode Current
Set Point
The MAX3738 operates in APC mode at all times. The
bias current is automatically set so average laser power
is determined by the APCSET resistor:
P AVG = I MD / ρ MON
The APCSET pin controls the set point for the monitor
diode current. An internal current regulator establishes
the APCSET current in the same manner as the
MODSET pin. See the Photodiode Current vs. R APCSET
graph in the Typical Operating Characteristics and
select the value of R APCSET that corresponds to the
required current at +25 ° C.
I MD = 1/2 x V REF / R APCSET
graph in the Typical Operating Characteristics and
select the value of R MODSET that corresponds to the
required current at +25 ° C:
I MOD = I MODS + K x I BIAS + I MODT
I MODS = 268 x V REF / R MODSET
I MODT = TC x (T - T TH ) | T > T TH
I MODT = 0 | T < T TH
An external resistor at the MODBCOMP pin sets current
proportional to I BIAS . Open circuiting the MODBCOMP
pin can turn off the interaction between I BIAS and I MOD :
K = 1700 / (1000 + R MODBCOMP ) ±10%
If I MOD must be increased from I MOD1 to I MOD2 to
maintain the extinction ratio at elevated temperatures,
the required compensation factor is:
K = (I MOD2 - I MOD1 ) / (I BIAS2 - I BIAS1 )
A threshold for additional temperature compensation
can be set with a programming resistor at the
TH_TEMP pin:
T TH = -70 ° C + 1.45M Ω / (9.2k Ω + R TH_TEMP ) ° C ±10%
The temperature coefficient of thermal compensation
above T TH is set by R MODTCOMP . Leaving the
MODTCOMP pin open disables additional thermal
compensation:
TC = 1 / (0.5 + R MODTCOMP (k Ω )) mA/ ° C ±10%
12
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX3738ETG+ | 功能描述:激光驱动器 155-4.25Gbps SFF/SFP w/Extinction RC 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 |
| MAX3738ETG+GD0 | 功能描述:激光驱动器 155Mbps to 4.25Gbps SFF/SFP Laser Driver with Extinction Ratio Control 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 |
| MAX3738ETG+T | 功能描述:激光驱动器 155-4.25Gbps SFF/SFP w/Extinction RC 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 |
| MAX3738ETG+TGD0 | 功能描述:激光驱动器 155Mbps to 4.25Gbps SFF/SFP Laser Driver with Extinction Ratio Control 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 |
| MAX3738ETG-T | 功能描述:激光驱动器 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 |
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