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Topic: +5V on USBVCC when powering from external source? (Read 1 time) previous topic - next topic

raschemmel


Garreth

Pulling doesnt help.
But I may have figured it out. At my Mega board, the P-mosfet is labeled as A1SHB and googling this out returns me to this note http://pdf.datasheetcatalog.com/datasheet/vishay/70627.pdf . It has different Vds, and lots of other parametes, so maybe I got the mega built on cheaper parts?

Wawa

I took out everything from the board - no shields, no sensors, nothing. Then I connected ONLY 9V battery to 2.1mm jack power input and I started measuring.
Are you sure the battery remained more than 7.3volt (6.6volt Vin + 0.7volt reverse protection diode) during measurements. 9volt batteries droop very quickly.
Leo..

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