PIC enable.....AP6714 Boost Converter

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Moderator: phalanx

PIC enable.....AP6714 Boost Converter

Postby haseeb » Mon Mar 12, 2012 2:20 am

Hello

I'm doing an experiment with a 3.3V PIC18F67k22. Everything is working fine and all i want for my next stage development is to enable disable
a boost converter 'AP6714' via its enable/disable pin from a command comming from the PIC. From the datasheet link below, i know how to connect
etc. all i'm concerned is what value should i use for Rtop and Rbottm to get a 5V output. So my PIC will enable the boost converter with 3.3V and then I will want 5V output.

Boost Converter datasheet.....
http://www.diodes.com/datasheets/AP6714.pdf

Can anyone suggest the values for Rtop and Rbottom?

Haseeb
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Re: PIC enable.....AP6714 Boost Converter

Postby phalanx » Tue Mar 13, 2012 9:41 am

It's odd that they don't explicitly say how to select your feedback resistors in the datasheet.

Given that the feedback reference voltage is 1.23V and the recommended minimum Rbottom value is 100KΩ:

I = 1.23V / 100KΩ = 0.0123mA (current through the voltage divider)
Rfb= 5V / 0.0123mA = 406.5KΩ (Total resistance of the feedback voltage divider)
Rtop = 406.5KΩ - 100KΩ = 306.5KΩ (Rtop = Rfb - Rbottom)

so...

Rtop = 306.5KΩ and Rbottom = 100KΩ

I would try those values and see if you get a 5V output.

-Bill
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Re: PIC enable.....AP6714 Boost Converter

Postby haseeb » Wed Mar 14, 2012 12:23 am

BIll

Thank you very much for your help. I will check the values and then let you know the result.

Regards
Haseeb
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