欢迎访问ic37.com |
会员登录 免费注册
发布采购

DI-102 参数 Datasheet PDF下载

DI-102图片预览
型号: DI-102
PDF下载: 下载PDF文件 查看货源
内容描述: 降低过电压的以太网供电( PoE)的 [Lowered Overvoltage for Power over Ethernet (PoE)]
分类和应用: 以太网
文件页数/大小: 2 页 / 243 K
品牌: POWERINT [ Power Integrations ]
 浏览型号DI-102的Datasheet PDF文件第1页  
DI-102  
^
$ R + R  
4
h
5
V + V  
L
Design Formulae  
^
Q1(BE)h  
R5  
VIN(th)  
=
Component values are calculated as follows:  
VC - V  
R6  
VOV_OFF  
=
b
IOV_OFF  
-
L l $ RLS + VL  
IEEE 802.3af overvoltage requiements are:  
VOV_OFF = 63 VDC  
VIN(th) = 60 VDC  
Input voltage turn-off  
OVSD becomes active  
Key Design Points  
From the DPA-Switch data sheet we have the following:  
• 1 % accuracy resistors should be used to maintain the  
highest accuracy for the OV on and off thresholds.  
• To avoid interfering with the under-voltage thresholds, the  
voltage VIN(th), must be programmed above under-voltage  
levels.  
IOV_OFF = 135 µA  
This is the L-pin current at which  
the device turns off  
L-pin voltage at IL = IOV_OFF  
Control-pin voltage  
VL = 2.5 VDC  
VC = 5.8 VDC  
• The DMAX limit of the DPA-Switch linearly decreases with  
increasing input voltage (increasing L-pin current), when  
using only resistor RLS for under/overvoltage detection.  
However when the overvoltage threshold is modified with  
additional circuitry, this will effectively change the DMAX  
limitproportionallyatvoltagesabovethethresholdvoltage  
(VIN(th)). The power supply designer should therefore make  
sure that the power supply can still deliver the required  
power with the reduced maximum duty cycle at high line.  
Assumptions:  
V
= 0.7 VDC  
Transistor base-emitter voltage  
Transistor minimum current gain  
This is the ratio of transistor bias  
versus collector current (larger K  
gives stronger bias)  
β Q=1(B1E0) 0  
K = 10  
Resistor values R4, R5 and R6 are calculated as:  
V
OV_OFF - VL - V $ b  
^
Q1(BE)h  
R4 $  
R5 $  
R6 =  
IOV_OFF $ K  
V + V  
Q1(BE)h  
L
$ R  
^
OV_OFF - VL - VQ1(BE)  
4
V
^
h
VL - VC $ RLS  
OV_OFF - IOV_OFF $ RLS - VL  
V
For the latest updates, visit www.powerint.com  
Power Integrations reserves the right to make changes to its products at any time to improve reliability or manufacturability. Power Integrations does  
not assume any liability arising from the use of any device or circuit described herein. POWER INTEGRATIONS MAKES NO WARRANTY HEREIN AND  
SPECIFICALLY DISCLAIMS ALL WARRANTIES INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A  
PARTICULAR PURPOSE, AND NON-INFRINGEMENT OF THIRD PARTY RIGHTS. The products and applications illustrated herein (transformer construction and  
circuits external to the products) may be covered by one or more U.S. and foreign patents or potentially by pending U.S. and foreign patent applications assigned to  
Power Integrations. A complete list of Power Integrations' patents may be found at www.powerint.com. Power Integrations grants its customers a license  
under certain patent rights as set forth at http://www.powerint.com/ip.htm.  
The PI logo, TOPSwitch, TinySwitch, LinkSwitch, DPA-Switch, EcoSmart, PI Expert and PI FACTS are trademarks of  
Power Integrations, Inc. Other trademarks are property of their respective companies. Copyright 2005, Power Integrations, Inc.  
Power Integrations  
5245 Hellyer Avenue  
San Jose, California 95138  
MAIN PHONE NUMBER  
+1 408-414-9200  
APPLICATIONS HOTLINE  
+1 408-414-9660  
APPLICATIONS FAX  
+1 408-414-9760  
For a complete listing of worldwide sales offices,  
please visit www.powerint.com  
A
8/05  
www.powerint.com