Hi guys, I was wondering if you could help me out on a little circuit problem. I want to start moving towards the ATTiny chips for some of my smaller projects. However, being clumsy as I am, sometimes I do the pinout backwards when there's Dsub's involved since the pinouts are in reverse when looking from the back compared to the front... In any case, I wanted to idiot-proof my PCB so that the chip will be protected when I reverse the leads by adding a diode. However, if my understanding is correct, it will create a voltage drop on the line, so my chip will no longer be getting the correct voltage.
Am I right about my assumption? And are there any ways around this?
That is correct all diodes have some forward voltage drop value. A schottky diode is a good choice for your case.
When current flows through a diode there is a small voltage drop across the diode terminals. A normal silicon diode has a voltage drop between 0.6–1.7 volts, while a Schottky diode voltage drop is between approximately 0.15–0.45 volts. This lower voltage drop can provide higher switching speed and better system efficiency.