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參數(shù)資料
| 型號： | MAX3738ETG |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類： | 其它接口 |
| 英文描述： | 1Gbps to 2.7Gbps SFF/SFP Laser Driver with Extinction Ratio Control |
| 中文描述： | SPECIALTY INTERFACE CIRCUIT, QCC24 |
| 封裝： | 4 X 4 MM, QFN-24 |
| 文件頁數(shù)： | 10/14頁 |
| 文件大?。?/td> | 403K |
| 代理商： | MAX3738ETG |
M
Safety Circuitry
The safety circuitry contains a disable input
(TX_DISABLE), a latched fault output (TX_FAULT), and
fault detectors (Figure 5). This circuitry monitors the
operation of the laser driver and forces a shutdown if a
fault is detected (Table 1). The TX_FAULT pin should
be pulled high with a 4.7k
to 10k
resistor to V
CC
as
required by the SFP MSA. A single-point fault can be a
short to V
CC
or GND. See Table 2 to view the circuit
response to various single-point failure. The transmit
fault condition is latched until reset by a toggle or
TX_DISABLE or V
CC
. The laser driver offers redundant
laser diode shutdown through the optional shutdown
circuitry as shown in the
Typical Applications Circuit
.
This shutdown transistor prevents a single-point fault at
the laser from creating an unsafe condition.
Safety Circuitry Current Monitors
The MAX3738 features monitors (BC_MON, PC_MON)
for bias current (I
BIAS
) and photocurrent (I
MD
). The
monitors are realized by mirroring a fraction of the cur-
rents and developing voltages across external resistors
connected to ground. Voltages greater than V
REF
at
PC_MON or BC_MON result in a fault state. For exam-
ple, connecting a 100
resistor to ground at each mon-
itor output gives the following relationships:
V
BC_MON
= (I
BIAS
/ 82) x 100
V
PC_MON
= I
MD
x 100
External sense resistors can be used for high-accuracy
measurement of bias and photodiode currents. On-chip
isolation resistors are included to reduce the number of
components needed to implement this function.
1Gbps to 2.7Gbps SFF/SFP Laser Driver with
Extinction Ratio Control
10
______________________________________________________________________________________
PIN
CIRCUIT RESPONSE TO OVERVOLTATGE OR
SHORT TO V
CC
Does not affect laser power.
Modulation and bias currents are disabled.
The optical average power increases, and a fault occurs
if V
PC_MON
exceeds the threshold. The APC loop
responds by decreasing the bias current.
The optical average power decreases and the APC loop
responds by increasing the bias current. A fault state
occurs if V
BC_MON
exceeds the threshold voltage.
CIRCUIT RESPONSE TO UNDERVOLTAGE OR
SHORT TO GROUND
TX_FAULT
TX_DISABLE
Does not affect laser power.
Normal condition for circuit operation.
The optical average power decreases, and the APC loop
responds by increasing the bias current. A fault state
occurs if V
BC_MON
exceeds the threshold voltage.
The optical average power increases and a fault occurs
if V
PC_MON
exceeds the threshold. The APC loop
responds by decreasing the bias current.
IN+
IN-
MD
This disables bias current. A fault state occurs.
The APC circuit responds by increasing the bias current
until a fault is detected; then a fault* state occurs.
SHUTDOWN
Does not affect laser power. If the shutdown circuitry is
used, the laser current is disabled.
Does not affect laser power.
BIAS
In this condition, the laser forward voltage is 0V and no
light is emitted.
Fault state* occurs. If the shutdown circuitry is used, the
laser current is disabled.
OUT+
The APC circuit responds by increasing the bias current
until a fault is detected; then a fault state* occurs.
Fault state* occurs. If the shutdown circuitry is used, the
laser current is disabled.
OUT-
PC_MON
BC_MON
Does not affect laser power.
Fault state* occurs.
Fault state* occurs.
Does not affect laser power.
Does not affect laser power.
Does not affect laser power.
APCFILT1
I
BIAS
increases until V
BC_MON
exceeds the threshold
voltage.
I
BIAS
increases until V
BC_MON
exceeds the threshold
voltage.
APCFILT2
I
BIAS
increases until V
BC_MON
exceeds the threshold
voltage.
I
BIAS
increases until V
BC_MON
exceeds the threshold
voltage.
MODSET
APCSET
*
A fault state asserts the TX_FAULT pin, disables the modulation and bias currents, and asserts the SHUTDOWN pin.
Does not affect laser power.
Does not affect laser power.
Fault state* occurs.
Fault state* occurs.
Table 2. Circuit Responses to Various Single-Point Faults
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX3738ETG+ | 功能描述:激光驅(qū)動器 155-4.25Gbps SFF/SFP w/Extinction RC 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 |
| MAX3738ETG+GD0 | 功能描述:激光驅(qū)動器 155Mbps to 4.25Gbps SFF/SFP Laser Driver with Extinction Ratio Control 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 |
| MAX3738ETG+T | 功能描述:激光驅(qū)動器 155-4.25Gbps SFF/SFP w/Extinction RC 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 |
| MAX3738ETG+TGD0 | 功能描述:激光驅(qū)動器 155Mbps to 4.25Gbps SFF/SFP Laser Driver with Extinction Ratio Control 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 |
| MAX3738ETG-T | 功能描述:激光驅(qū)動器 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 |
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