push-pull, push-up. open-drain, so on and so on...

[johnli100]

strong to open drain

For the pad design, we often hear of push-pull, push-up, push-down, open-drain, and open-source. Wiz on earth they are??? Why should we chose the different mode? Any reason?

Also, many time I hear of pin-strapping. What is it? Normally, we should use input pin or outout pin to do pin-strapping? How does pin-strapping work?

Is there any excellent document on these topic? Or an experter can kindly give some detail info on them.

Waiting 4 ur response ...:?:

 

[visualart]

push-pll, push-up. open-drain, so on and so on...

pull-up: pad be connected the Vdd through a resistor, If the pad isn't connecting any wire,
the input signal equal to "1".
pill-down: connect to vss, and enqual to "0"

 

[Hero]

In the case of the push-pull pad you have strong low and strong high.

In the case of the push-up you have strong low and weak high without external resistor or current source.

In the case of the open-drain you have strong low and high impedance state.

You can use open-drain pad to connect more signals to one common line with active low e.g. interrupt request line. In this case you have weak high.

So think about strong high, strong low, weak high, weak low, Hi-Z or Bus holder output states