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Altera_Forum
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16 years ago

MAX3000 CPLD bi-directional I/O with 5V pull-up

Hi How would I create a bi-directional pin with open-collector output on a MAX3000 CPLD? I have started the design with an open collector driver driving the pin and a 541 type buffer fo...
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Altera_Forum
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16 years ago

Thanks for the reply,

Yes, MAX3000A and yes, 74xx541.

I had previously read this part of the datasheet.

This information is not really what concerns me as it meets all my requirements.

It's the gates inside the device and the way in which they operate on the specified pin that concerns me.

For this to work the "pin" must really just be a wire so that the open-collector drivers can pull the "pin" down and the 74xx541 buffer simply "see and transfer" the "pin" level.

So on my schematic I have a 74xx573 (latch) followed by open collector drivers connected to the pin. On the pin I also have the 74xx541 so that I can read back the output state.

My question is really how do I define the pin structure?

(Did I mention that I am new at this)

Thanks

Andre