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Topic: atMega8L -- any external components required at all? (Read 3120 times) previous topic - next topic

pico



It's "weak".  30K to 60K ohms.  In some situations that makes it unreliable.

And, the cost of a single 4.7K to 10K resistor is how much?



It's not the cost, it's the understanding. ;-)
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dhenry

Quote
I was just wondering what external components (if any) I must/would be advised to have for an atMega8L.


Must have: none.
Advised to have: a decoupling capacitor on AVref.
What I would have: a decoupling capacitor on Vcc, and a rc or lc filter on Avref.


fungus


and a 4.7k pullup resistor on RESET.


The internal pullup by itself isn't reliable? Surprising.


It's "weak".  30K to 60K ohms.  In some situations that makes it unreliable.

And, the cost of a single 4.7K to 10K resistor is how much?



I was quite surprised by this, too. The only thing I can think of is Atmels obsession with power consumption. I'm guessing the extra microamp that a lower resistor would consume keeps Atmel engineers awake at night.

Only unwashed people with filthy, dirty power supplies would need 4.7k pullups.
No, I don't answer questions sent in private messages (but I do accept thank-you notes...)

dhenry

Even 30k pull-up can be considered too low for some applications - touch sensing for example.

Many newer chips tend to go closer to 100k - many times they are actually 1ua current sources. A 4.7k pull-up inside a chip would have been a marketing / application disaster.

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