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參數(shù)資料
| 型號： | MAX3865EGJ |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類： | 其它接口 |
| 英文描述： | 2.5Gbps Laser Driver with Automatic Modulation Control |
| 中文描述： | SPECIALTY INTERFACE CIRCUIT, CQCC32 |
| 封裝： | 5 X 5 MM, 0.90 MM HEIGHT, QFN-32 |
| 文件頁數(shù)： | 7/16頁 |
| 文件大?。?/td> | 633K |
| 代理商： | MAX3865EGJ |
Detailed Description
The MAX3865 laser driver consists of two main parts: a
high-speed modulation driver and biasing block as
shown in Figure 4. Outputs to the laser diode are a
switched modulation current and a steady bias current.
Two servo loops may be enabled to control bias and
modulation currents for constant optical power and
extinction ratio.
The MAX3865 requires a laser with a built-in monitor
diode to provide feedback about the optical output.
The average laser power, as sensed by the monitor
diode, is controlled by the APC servo loop. Peak-to-
peak modulation current is controlled by the AMC servo
loop. The modulation output stage uses a programma-
ble current source with a maximum current of 60mA. A
high-speed differential pair switches this source to the
laser diode. The clock and data inputs to the modula-
tion driver may use CML, PECL, and other logic levels.
The optional clock signal can be used to synchronize
data transitions for minimum pattern-dependent jitter.
Clock/Data Input Logic Levels
The MAX3865 is directly compatible with V
CC
-refer-
enced CML. Other logic interfaces are possible. For
V
CC
-referenced CML or AC-coupled logic, tie V
DR
and
V
CR
to V
CC
. For other DC-coupled differential signals,
float V
DR
and V
CR
(Figure 5). To prevent excess power
dissipation in the input matching resistors, keep the
instantaneous input voltage within 1.2V of V
DR
or V
CR
as specified in the electrical characteristics.
Optional Input Data Retiming
To eliminate pattern-dependent jitter in the input data, a
synchronous differential clock signal should be con-
nected to the CLK+ and CLK- inputs, and the RTEN
control input should be tied high. Input data retiming
occurs on the rising edge of CLK+. If RTEN is tied low,
the retiming function is disabled and the input data is
directly connected to the output stage. When no clock
is available, tie CLK+ to V
CC
, ground CLK- through a
1.5k
resistor, and leave V
CR
open.
Operating Mode
The MAX3865 can be set in four operating modes,
depending on applications requirements. Mode selec-
tion is by two TTL-compatible inputs (see Table 1).
APC Loop
In APC mode, a servo loop maintains the average
current from the monitor diode at a level set by the
APCSET input. Laser bias current is varied in this mode
to maintain the monitor diode current. The BIASMAX
input must be set to a value larger than the maximum
expected bias current. In this mode, BIASMAX limits the
maximum bias current to the laser if the control loop
fails. The
FAIL
pin will go low if average I
MD
≠
I
APCSET
.
Mark-Density Compensation
Average power control assumes 50% mark density for
times greater than about 100ns. For long patterns or sit-
uations where 50% mark density does not apply, the
MAX3865 provides mark-density compensation. The
APCSET reference is increased by an amount propor-
tional to the mark density multiplied by the modulation
amplitude. The AMCSET input is used as an estimate of
the peak-to-peak modulation current when the mark
density is not 50%. Mark-density compensation is
active in both APC and AMC control modes.
AMC Loop
In AMC mode, a servo loop maintains the peak-to-peak
current from the monitor diode at a level set by the
AMCSET input. Laser modulation current is varied in
this mode to maintain the monitor diode current. The
MODMAX input must be set to a value larger than the
maximum expected modulation current. In this mode,
MODMAX limits the maximum modulation current to the
laser if the control loop fails. The
FAIL
pin will go low if
peak-to-peak I
MD
≠
I
AMCSET
. The APC loop is active
when in the AMC mode. In AMC mode, mark-density
compensation is automatic.
M
2.5Gbps Laser Driver with Automatic
Modulation Control
_______________________________________________________________________________________
7
EN0
0
0
1
1
EN1
0
1
0
1
OPERATING MODE
Shutdown
Manual
APC
AMC
DESCRIPTION
Bias and modulation currents off
BIASMAX programs laser bias, MODMAX programs modulation
APCSET programs laser bias, MODMAX programs modulation
AMCSET programs modulation current and APCSET programs bias
Table 1. Mode Selection
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX3866E/D DIE | 制造商:Maxim Integrated Products 功能描述: |
| MAX3867E/D DIE | 制造商:Maxim Integrated Products 功能描述: |
| MAX3867ECM | 功能描述:激光驅(qū)動器 Integrated Circuits (ICs) 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 |
| MAX3869E/D | 功能描述:激光驅(qū)動器 DICE SALES DICE12 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 |
| MAX3869E/D DIE | 制造商:Maxim Integrated Products 功能描述: |
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