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How to generate 15V from 5V USB port?

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Newbie level 2
May 30, 2005
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Hi All!

I have a +5V and I need a +15V generated from that +5V. This power supply is the USB port.

The currency is very low(Maximun 50mA).

It will be in 15V for 3 or 4 sec.

So, I need to generate 15V from 5V USB port.

Is that possible?

Thanks all!!!

mc34063 calc

Yes it is posible. and I made it for my pic programmer. Mc34063 used. Here is the calculator:
**broken link removed**

mc34063a calculator

yes it is possible:
you can use MC34063 switching voltage regulator
try download it's datasheet from:
**broken link removed**


usb 15v

Could you post you programmer schematic?

So I can how to do this boost converter.

Thanks you guys!


mc34063 calculation

what about clamping the 5v.. not sure if its possible to draw 50 mA from the circuit, what do people think ?

mc34063 5v circuit

there is a chip and easy 555 timer circuit can do this job search google for it

usb to 15v

You can use a boost converter, such as the LT1615 from Linear Tech:,C1,C1003,C1042,C1031,C1061,P1775

or MAX8575 from Maxim

The USB port can source up to 100mA, as per the USB specification.
Since the available input power is Pin=5V*100mA=500mW, your output current can only be Iout=Pout/Vout=Pin*η/Vout. Typically, η=0.9 for a boost (though it can be lower), so your maximum output current can only be Iout=500mW*0.9/15V=30mA. This is a best-case scenario. In reality, the input voltage will be lower than 5V, due to voltage drops in the USB cable and connectors. Therefore, an output current of about 25mA is a more realistic expectation.

Does that work for you?

calculate mc34063 .xls

You could use a switching regulator -- check out

**broken link removed**

for more information. You can enter in the details of your specifications and
it will suggest a part for you. You can use this as your starting point.

Best of luck,

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