参数资料
| 型号： | MAX3766EEP+T |
| 厂商： | Maxim Integrated |
| 文件页数： | 9/20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
? 300 ?
Automatic Power Control
Transmitters employing a laser with monitor photodiode
can use the APC circuit to maintain constant power,
regardless of laser threshold changes due to temperature
and aging. The APC circuit consists of the POWERSET
current mirror and the monitor diode amplifier.
The POWERSET current mirror provides an accurate
method of programming the back facet monitor photo-
diode current, which is assumed to be proportional to
laser output power. An external resistor from REF1 to
POWERSET programs the current in the unity-gain cur-
rent mirror. R POWERSET can be estimated as follows:
1.55V
R POWERSET =
I MOD
The monitor-diode amplifier senses the current from the
monitor photodiode at MD, provides gain, and adjusts
the laser bias programming current (I LBP ). The monitor-
diode amplifier forces the monitor-diode current to
equal the current programmed at POWERSET. The
monitor-diode amplifier can reduce the laser bias pro-
gramming current, but cannot increase it. Therefore,
the APC circuit can adjust laser bias current between 0
and the setting determined by R BIASMAX .
When the APC feedback loop is closed, the voltage at
MD is approximately 2V below V CC . If the loop cannot
close due to excess or insufficient photocurrent, a fail-
ure is detected by the failure-detection circuit. Internal
circuitry prevents the voltage at MD from dropping
below V CC - 3.2V.
The stability and time constant of the APC feedback
loop is determined by an external compensation
capacitor (C MD ) of at least 0.1μF. Connect the com-
pensation capacitor from V CC to MD, as shown in
Typical Application Circuits , to ensure a smooth start-
the reference voltage would rise, the current at POWER-
SET would increase, and the APC loop would attempt to
add laser current beyond the intended value.
Either failure condition causes the FAIL output to assert
TTL low. The FAIL output buffer is an open-collector
output and is designed to operate with a 5.1k ? external
pull-up resistor.
Safety/Start-Up Circuit
The safety circuit includes the digital logic needed to
provide a latched internal shutdown signal (SHDN) for
disabling the laser if a failure condition exists. The
MAX3766 produces less than 20μA of total laser cur-
rent when disabled by safety features or by the
ENABLE input. Figure 4 is a simplified schematic of the
safety circuit.
If ENABLE is low or open, the laser bias and modula-
tion outputs are disabled by SHDN, regardless of the
state of the safety logic. The TTL-compatible ENABLE
input is internally pulled low with a 100k ? resistor.
There are two useful safety configurations: failure
indication and latched shutdown.
Failure-Indication Configuration
Select the failure-indication configuration by connecting
SAFETY to ground. In this configuration, a failure condi-
tion is reported at FAIL , but does not cause a latched
shutdown. This configuration requires no additional cir-
cuitry for start-up.
V MD
V CC
up at power-on or transmitter enable.
If a monitor diode is not available, the APC feature can
2V
200mV
be disabled by connecting R POWERSET to GND and
leaving MD unconnected.
Failure Detection
Figure 3 shows a simplified schematic of the failure-
detection circuit. The failure-detection circuit senses
two conditions. First, if the APC control loop cannot
control the monitor current due to laser undercurrent,
overcurrent, or a fault condition, a window comparator
detects that V MD is above or below V CC - 2V and
asserts the failure signal. Second, if REF1 is shorted to
V REF1
V BANDGAP
0.5V
200mV
FAILURE
(INTERNAL)
the positive supply (or any another voltage above the
normal operating level), a comparator detects this con-
dition and asserts the failure signal. If left undetected,
Figure 3. Failure-Detection Circuit (Simplified)
_______________________________________________________________________________________
9
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相关代理商/技术参数 |
参数描述 |
|---|---|
| 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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