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Re: Protecting I/Os + current sensing

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  • manifold
    Here is a schematic of a possible protection circuit. Now do you see where the 1V drop comes from? If the I/O pin on the processor is at 5V and 15mA flows
    Message 1 of 13 , Jan 31, 2003
      Here is a schematic of a possible protection circuit.
      Now do you see where the 1V drop comes from? If the
      I/O pin on the processor is at 5V and 15mA flows
      through the series resistor, What is the voltage on
      the other side of the resistor?

      --- In Electronics_101@yahoogroups.com, "Kelvin Lau
      <kelau@h...>" <kelau@h...> wrote:
      > I'm using a Microchip PIC16F874. Which can source
      25mA per I/O, but
      > have a max. of 200mA sourcing capacity for the whole
      chip. I don't
      > quite understand your explanation regarding the max.
      resistance I can
      > have is 68ohm. what's the 1V drop coming from?
      >
      > Kelvin
      >


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