- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄384665 > MAX3668EHJ (MAXIM INTEGRATED PRODUCTS INC) +3.3V, 622Mbps SDH/SONET Laser Driver with Automatic Power Control PDF資料下載
參數(shù)資料
| 型號： | MAX3668EHJ |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類： | 其它接口 |
| 英文描述： | +3.3V, 622Mbps SDH/SONET Laser Driver with Automatic Power Control |
| 中文描述： | SPECIALTY INTERFACE CIRCUIT, PQFP32 |
| 封裝： | 5 X 5 MM, 1 MM HEIGHT, MS-026AAA-HD, TQFP-32 |
| 文件頁數(shù)： | 8/12頁 |
| 文件大?。?/td> | 435K |
| 代理商： | MAX3668EHJ |
M
+3.3V, 622Mbps SDH/SONET
Laser Driver with Automatic Power Control
8
_______________________________________________________________________________________
Programming the APC Loop
When the MAX3668’s APC feature is used, program the
average optical power by adjusting the APCSET resis-
tor. To select this resistor, determine the desired moni-
tor current to be maintained over temperature and life.
Refer to the Monitor Diode Current vs. APC Set Resistor
graph in the
Typical Operating Characteristics
and
select the value of R
APCSET
that corresponds to the
required current.
Interfacing with the Laser Diode
To minimize optical output aberrations due to the laser
parasitic inductance, an RC shunt network may be
used
(see Typical Operating Circuit)
. If R
L
represents
the laser diode resistance, the recommended total
resistance for R
D
+ R
L
is 10
. Starting values for coaxi-
al lasers are R
FILT
= 20
and C
FILT
= 5pF. R
FILT
and
C
FILT
should be experimentally adjusted to optimize
the output waveform. A bypass capacitor should also
be placed as close to the laser anode as possible for
best performance.
Pattern-Dependent Jitter (PDJ)
When transmitting NRZ data with long strings of consec-
utive identical digits (CID), LF droop can contribute to
pattern-dependent jitter. To minimize this pattern-depen-
dent jitter, two external components must be properly
chosen: capacitor C
APC
, which dominates the APC loop
time constant; and AC-coupling capacitor C
D
.
To filter out noise effects and guarantee loop stability,
the recommended value for C
APC
is 0.1μF. This results
in an APC loop bandwidth of 20kHz. Consequently, the
pattern-dependent jitter associated with an APC loop
time constant can be ignored.
The time constant associated with the DC blocking
capacitor on I
MOD
will have an effect on PDJ. It is
important that this time constant produce minimum
droop for long consecutive bit streams.
Referring to Figure 4, the droop resulting from long time
periods without transitions can be represented by the
following equation:
AC coupling of I
MOD
results in a discharge level for
τ
that is equal to P
AVG
. An overall droop of 6% relative to
P
p-p
equates to a 12% droop relative to P
AVG
. To
ensure a droop of less than 12% (6% relative to P
p-p
),
this equation can be solved for
τ
as follows:
-t
τ
=
ln
If t
1
equals 80 consecutive unit intervals without a tran-
sition, the time constant associated with the DC block-
ing capacitor needs to be longer than:
τ
AC
≥
R
AC
C
D
= 7.8 (80 bits) (1.6ns/bit) = 1.0μs
R
FILT
can be ignored for C
FILT
<< C
D
, therefore the
estimated value of R
AC
is:
R
AC
= 20
(R
D
+ r
LASER
)
Assuming R
D
= 5
, and r
LASER
= 5
:
R
AC
= 6.7
with C
D
= 1.0μF,
τ
AC
= 6.7μs.
Input Termination Requirement
The MAX3668 data inputs are PECL-compatible.
However, it is not necessary to drive the MAX3668 with
a standard PECL signal. As long as the specified com-
mon-mode voltage and differential voltage swings are
met, the MAX3668 will operate properly.
Calculate Power Consumption
The total power dissipation of the MAX3668 can be esti-
mated by the following:
P = V
CC
×
I
CC
+ (V
CC
- V
f
)
×
I
BIAS
+ I
MOD
(V
CC
- 20
×
I
MOD
/ 2)
where I
BIAS
is the maximum bias current set by R
BIAS-
MAX
, I
MOD
is the modulation current, and V
f
is the typi-
cal laser forward voltage.
Applications Information
The following is an example of how to set up the
MAX3668.
Select Laser
A communication-grade laser should be selected for
622Mbps applications. Assume the laser output aver-
age power is P
AVE
= 0dBm, the minimum extinction
(1 - 0.12)
= 7.8t
(100% - DROOP) = e
-t
τ
DROOP
t
P
AVG
P
p-p
τ = ∞
τ << τ
AC
τ
AC
t
1
Figure 4. Droop
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MAX3669 | Single LVDS Transmitter 8-SOIC -40 to 85 |
| MAX3669EHJ | +3.3V, 622Mbps SDH/SONET Laser Driver with Current Monitors and APC |
| MAX3672 | Low-Jitter 155MHz/622MHz Clock Generator |
| MAX3675EHJ | 622Mbps, Low-Power, 3.3V Clock-Recovery and Data-Retiming IC with Limiting Amplifier |
| MAX3675 | 622Mbps, Low-Power, 3.3V Clock-Recovery and Data-Retiming IC with Limiting Amplifier |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX3668EHJ+ | 功能描述:激光驅(qū)動器 3.3V 622Mbps SDH/SONET 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 |
| MAX3668EHJ+T | 功能描述:激光驅(qū)動器 3.3V 622Mbps SDH/SONET 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 |
| MAX3668EHJ-T | 功能描述:激光驅(qū)動器 3.3V 622Mbps SDH/SONET 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 |
| MAX3668EVKIT | 功能描述:激光驅(qū)動器 Evaluation Kit for the MAX3668 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 |
| MAX3669E/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 |
發(fā)布緊急采購，3分鐘左右您將得到回復。