Topic: Comparator question.
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Feb 08, 2012, 10:25 pm
I'm currently working on a project to design an Arduino card from scratch and the only thing im missing now is a way to compare the Vin voltage against the USB-vcc and chooses the highest one.
The Uno card as far as i can tell uses a comparator to compare the voltage devided Vin-voltage against the voltage given by the 3.3V regulator and if the voltage is higher than the 3.3V it closes the transistor. Is this the best way to do this or are there IC-s that can compare the actual Vin agains the USB-vcc without the use of the transistor to block of the usb-voltage when there is a sufficient Vin-voltage?
Thanks in advance for all help:)