Need Precise 5v USB Power Supply

My system Lenovo 3000g400 is suffering from USB IC leakage problem and Because of this I am Only Getting 4.25v at USB .
I need A circuit which is very precise and can Be used instead of my USB Power , and Connecting the Data lines D1 and D2 as If, and connecting the power from an external Circuit

Please I need it to Connect My USB Modem ,(1 time it(modem) is destroyed due to low /high power and USB ) ;(

due to low /high power and USB? is it burnt? or ?

How about adding a powered USB hub between the ailing PC and the modem? The hub should provide clean power while the data goes through.

There is nothing precise about USB power. If you really need exactly 5.00V you should regulate the USB power down to a sub-voltage, like 3.3V, and use a fixed ratio switcher to boost it back to 5.00V with feedback from the 5.00V modem bus to the 3.3V regulator chip.

The Mode company Says it wa Over current But When I check the ports the voltage was Low !

---------- Post added at 21:27 ---------- Previous post was at 21:25 ----------

Seems ok .. But Can I build it OR Buy From Shop (If yes please tell the estimated Cost (I am from India))

If the load draws too much current the source will throttle back the voltage to protect itself. You will measure low voltage on the wires. Do you have the tools to measure the current?

Any computer supply shop should have a USB hub. In the USA a hub costs more than a mouse, but less than a keyboard. Get one that comes with its own power supply.

I have tools to measure the current . Without Load it shows 4.25v is Same.....

4.25V open circuit from a USB port looks like a bad port. But the powered hub may still fix your problem.

You can try a solution like

https://www.edaboard.com/thread196541.html

Alex

Thankz .. Please tell how can i build the 330uH coil ?

Provided the communication is ok, you may use a Powered hub whiich costs arround 300-500 rupees and available with most of the IT dealers arround. But i personally would recommend to get the port repaired instead finding other alternate ways out.
Cheers

I haven't made any coil like that , I usually buy them, they are available in stores.

Alex

I tried for repair they tells tat it will cost Rs.4000/- chip level service OR Rs.18000/- for mother board replacement. I will soon buy a New One but Before tat I have to use this for my current usage.

Any alternate IC ? I am unable to get LM2575 ..