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Boost conversion
Moderators: adafruit_support_bill, adafruit

Boost conversion

by tridentsx on Mon Feb 11, 2013 8:34 pm

I am looking for information/circuit examples about boost conversion.

I want to be able to boost 5v from USB all the way up to 25v in small steps and have it s/w controlled by an MCU. What is the best/simplest way to implement this ?

-- Always boost to 25v and then regulate it down with a DAC controlled transistor ?
-- Control the boost circuit somehow by outputting different frequency from the MCU?
-- Other ways of achieving same goal ?

I would also like to know how to use the ADC to measure current to implement a shut off if a certain current level is exceeded. Would I do that by measure voltage drop over a shunt ?

I am working an an universal device programmer and this is the part I am getting stuck at generating the VPP :?:
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Re: Boost conversion

by zener on Mon Feb 11, 2013 9:38 pm

-- Always boost to 25v and then regulate it down
Yes, with a MAX629 or similar
with a DAC controlled transistor
Something like that
-- Control the boost circuit somehow by outputting different frequency from the MCU?
You could, but that is probably a lot more difficult
-- Other ways of achieving same goal ?
I am sure there are many!
Would I do that by measure voltage drop over a shunt ?
You could, high-side shunt, low-side shunt. You could also look for the voltage dropping out.

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Re: Boost conversion

by tridentsx on Mon Feb 11, 2013 11:39 pm

Thanks a lot for pointing me in the direction of the max629, have ordered a few for testing.

Carl
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Re: Boost conversion

by adafruit_support_bill on Tue Feb 12, 2013 7:17 am

You can also look at the design page of the Ice Tube clock. That has a boost-converter circuit to drive the VFD display.

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