USB 5volts to 3.5volts

Thread Starter

noi

Joined Nov 8, 2006
2
hi duds,
how can i reduced a USB powered 5volts to 3.5volts with a atleast 500ma-800ma output? Please help. Thanks
 

Gadget

Joined Jan 10, 2006
614
According to USB specs, a USB port will supply 100mA unless a request is made by the connected device to deliver more current..(up to a MAX of 500mA)
2 USB ports can be used to get up to 1 Amp. Reducing to 3.5 Volts is a simple enough process, and would require a low dropout regulator.
Hubs will only supply 100mA max.

Looks like your main problem is going to be getting your USB port to supply more than 100mA and may require a dedicated USB interface chip.

Might be a lot easier to use the 5 volt rail in your PC from a spare Disk drive power connector, and reduce that to 3.5 volt.
 

Thread Starter

noi

Joined Nov 8, 2006
2
thanks GADGET, for the responsive reply... it really wants me to redured the voltage of the USB which is 5volts, yeah the problem is how can i maximized the current to 500mA?

Is there any way of modifiying or adding of a certain ICs or transistors so that to meet the 3.5volts output?
 
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