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參數(shù)資料
| 型號： | VSC7939W |
| 廠商： | VITESSE SEMICONDUCTOR CORP |
| 元件分類： | 其它接口 |
| 英文描述： | Laser Diode Driver with Automatic Power Control |
| 中文描述： | SPECIALTY INTERFACE CIRCUIT, UUC48 |
| 封裝： | DIE-48 |
| 文件頁數(shù)： | 14/18頁 |
| 文件大?。?/td> | 226K |
| 代理商： | VSC7939W |
VITESSE
Preliminary Data Sheet
VSC7939
SONET/SDH 3.125Gb/s
Laser Diode Driver with Automatic Power Control
Page 14
G52350-0, Rev 3.2
02/26/01
VITESSE
SEMICONDUCTOR CORPORATION
741 Calle Plano
Camarillo, CA 93012
Tel: (800) VITESSE
FAX: (805) 987-5896
Email: prodinfo@vitesse.com
Internet: www.vitesse.com
Applications Information
The following is a typical design example for the VSC7939 assuming 3.3V operation with APC.
Select a Laser
The Table 7 provides specifications for a typical communication-grade laser capable of operating at
2.5Gb/s.
Table 6: Typical Laser Characteristics
Select Resistor for APCSET
The monitor diode current is estimated by I
MD
= P
AVE
*
ρ
MON
= 6mW * 0.04mA/mW = 0.24mA. The I
MD
vs. R
APCSET
in
Typical Operating Characteristics
shows the resistor at APCSET should be 5k
.
Select Resistor for MODSET
To ensure some minimum extinction ratio over temperature and lifetime, assume an optimal extinction ratio
of 20 (13dB) at 25
°
C
. The modulation current may be calculated from the following equation:
I
MOD
= P
p-p
/
η
= 2 * P
AVE
* (r
e
-1) / (r
e
+1) /
η =
2 * 6mA * (20-1) / (20 + 1) / 0.4 = 27.1mA
The graph of I
MODSET
vs. R
MODSET
in
Typical Operating Characteristics
shows the resistor for MODSET
should be 8.5k
.
Select Resistor for BIASMAX
The maximum threshold current at +85
°
C and end of life must be determined. A graph of a typical laser
’
s
I
th
versus T
C
reveals a maximum threshold current of 30mA at 85
°
C
. Therefore, the maximum bias can be
approximated by:
I
BIASMAX
= I
TH-MAX
+ I
MOD
/ 2 = 30mA + 27.1mA / 2 = 43.6mA
The graph of I
BIASMAX
vs. R
BIASMAX
in
Typical Operating Characteristics
shows the resistor for BIASMAX
should be 5k
.
Select Resistors for MODMON and BIASMON
Assuming the modulation and bias currents never exceed 120mA, the following equations provide values
for the resistor at MODMON, RMODMON, and the resistor at BIASMON, RBIASMON:
R
MODMON
= 1V * 28 / 120mA = 233
R
BIASMON
= 1.6V * 35 / 120mA = 467
Symbol
Parameter
Value
Units
λ
P
AVE
I
th
ρ
MON
η
T
C
Wavelength
Average Optical Output Power
Threshold Current
Laser to Monitor Transfer
Laser Slope Efficiency
Operating Temperature Range
1310
6
6
0.04
0.4
nm
mW
mA
mA/mW
mW/mA
°
C
-40 to +85
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| VSC7940 | 制造商:VITESSE 制造商全稱:Vitesse Semiconductor Corporation 功能描述:SONET/SDH 3.125Gb/s Laser Diode Driver with Automatic Power Control |
| VSC7940RP | 制造商:VITESSE 制造商全稱:Vitesse Semiconductor Corporation 功能描述:SONET/SDH 3.125Gb/s Laser Diode Driver with Automatic Power Control |
| VSC7940W | 制造商:VITESSE 制造商全稱:Vitesse Semiconductor Corporation 功能描述:SONET/SDH 3.125Gb/s Laser Diode Driver with Automatic Power Control |
| VSC7958 | 制造商:VITESSE 制造商全稱:Vitesse Semiconductor Corporation 功能描述:2.5Gb/s High Speed Limiting Post Amplifier for OC-48/SDH-16 Applications |
| VSC7958CC | 制造商:VITESSE 制造商全稱:Vitesse Semiconductor Corporation 功能描述:2.5Gb/s High Speed Limiting Post Amplifier for OC-48/SDH-16 Applications |
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