Quote:
Originally Posted by DNSB
Having fun with one friend's USB to serial converter. We found that the printed on the board information for the jumper header that is supposed to set the output voltage to 1.8V, 3.3V or 5V is totally messed up in that it shows the jumpers backwards to the board layout ( so 3, 2, 1 instead of 1, 2, 3).
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The good UARTs use an FTDI232R chip which can use an external voltage for the logic level shifters.
There is the 5V already on USB Vbus, the chip has an internal 3.3V regulator and PCB manufacturers add a 1.8V, 2.5V and sometimes a redundant 3.3V regulator.