24FC1025 - HW questions

nicolad76

Hi all, since I am a beginner, I have a realy easy question for you.
I gave myself a good task just to force me to learn...I want to use three (I have only 3) 24FC1025 and while I was looking around for a schematic to make sure how to connect all the pins properly.
I noticed that the biggest difference with other EEPROM I2C from Microchip is on A2 which cannot be used and must be connected directly to Vdd.
No problem on that...my problem is on A0 and A1. Every website/article/man of the street says that they have to be connected to logical 1 or 0 according to the logic we all know.

My question is, logic value 1, does it means I can afford to connect the PIN directly to Vdd? No resistors in between?

Now, as I said I am a real beginner so either I question myself too much or my english does not help me to understand.
A 10K resistor should hurt, right? Does the direct connection to Vdd ensure the pin will read 1? I have seen a couple of projects and pin was tied to Vdd directly.
Which is the best way to do it?

Grazie mille!!!!!

Paul Baker

Yes a voltage can be directly connected to a pin which is an input and is within the supply rails (both of these conditions are true in your case). A 10kOhm resistor doesn't hurt because there is no current flowing through it (inputs typically draw no current), it neither hurts nor helps (but does cost you the price of a resistor). I am simplifying some things, but for your question these "overlooks" can indeed be overlooked.

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

Post Edited (Paul Baker (Parallax)) : 3/29/2008 2:41:05 AM GMT

nicolad76

I understand...thanks a lot
nicola