欢迎访问ic37.com |
会员登录 免费注册
发布采购

VSC7940-W 参数 Datasheet PDF下载

VSC7940-W图片预览
型号: VSC7940-W
PDF下载: 下载PDF文件 查看货源
内容描述: [Interface Circuit, 1.773 X 2.233 MM, DIE-48]
分类和应用: 驱动器二极管激光二极管功率控制
文件页数/大小: 16 页 / 170 K
品牌: VITESSE [ VITESSE SEMICONDUCTOR CORPORATION ]
 浏览型号VSC7940-W的Datasheet PDF文件第8页浏览型号VSC7940-W的Datasheet PDF文件第9页浏览型号VSC7940-W的Datasheet PDF文件第10页浏览型号VSC7940-W的Datasheet PDF文件第11页浏览型号VSC7940-W的Datasheet PDF文件第13页浏览型号VSC7940-W的Datasheet PDF文件第14页浏览型号VSC7940-W的Datasheet PDF文件第15页浏览型号VSC7940-W的Datasheet PDF文件第16页  
VITESSE  
SEMICONDUCTOR CORPORATION  
Preliminary Data Sheet  
SONET/SDH 3.125Gb/s  
Laser Diode Driver with Automatic Power Control  
VSC7940  
Applications Information  
The following is a typical design example for the VSC7940 assuming 5V operation with APC.  
Select a Laser  
The Table 8 provides specifications for a typical communication-grade laser capable of operating at  
2.5Gb/s.  
Table 6: Typical Laser Characteristics  
Symbol  
Parameter  
Value  
Units  
λ
Wavelength  
1310  
nm  
mW  
PAVE  
Ith  
ρMON  
η
Average Optical Output Power  
Threshold Current  
6
6
mA  
Laser to Monitor Transfer  
Laser Slope Efficiency  
Operating Temperature Range  
0.04  
mA/mW  
mW/mA  
°C  
0.4  
TC  
-40 to +85  
Select Resistor for APCSET  
The monitor diode current is estimated by IMD = PAVE * ρMON = 6mW * 0.04mA/mW = 0.24mA. The IMD  
vs. RAPCSET 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
= P / η= 2 * P  
* (r -1) / (r +1) / η = 2 * 6mA * (20-1) / (20 + 1) / 0.4 = 27.1mA  
MOD  
p-p  
AVE e e  
The graph of IMODSET vs. RMODSET 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 lasers  
I versus TC reveals a maximum threshold current of 30mA at 85°C. Therefore, the maximum bias can be  
th  
approximated by:  
IBIASMAX = ITH-MAX + IMOD / 2 = 30mA + 27.1mA / 2 = 43.6mA  
The graph of IBIASMAX vs. RBIASMAX in Typical Operating Characteristics shows the resistor for BIASMAX  
should be 5k.  
© VITESSE SEMICONDUCTOR CORPORATION 741 Calle Plano Camarillo, CA 93012  
Tel: (800) VITESSE FAX: (805) 987-5896 Email: prodinfo@vitesse.com  
Internet: www.vitesse.com  
Page 12  
G52357-0, Rev 3.2  
05/11/01