Bypass Resistor

It reduces dissipation in the 'regulator' if I've understood correctly what you're saying. I use the trick myself sometimes with plain 78xx regulators.

Graham

What would happen when the 5V drives a HIGH signal to the line would the 3.3V signal be affected? btw, those two signals are I/O pins with different signaling, one is 3.3V and the other one is 5V so it uses a bus switch to 'convert' the voltages.

You're going to need to point to a schematic.

Graham

the only thing i can picture in my mind is the by pass R used in many supplies to drain off the caps when the power is removed. just a guess.

I've found out(from the datasheet i'm referring) that the bypass resistor packs are NOT installed by default. They are ONLY installed when the FET switches(bus switch) are not installed (mutually exclusive).

:PEACE: yy7d6

I seriously doubt anyone cares frankly !

Graham

OK.

You responded ?

Why didn't you post a schematic somewhere ? - it might finally make some more sense !

Graham

See this link:

If you read the text, you will see this highly informative note:

"NOTE: These resistor packs are NOT installed by default. They are only installed when the proceeding (sic) page's FET switches are not installed (mutually exclusive)."

In this particular application, one may either use the bus switch, or simply pass the signals through directly. Note that the resistors are in fact 0 ohm devices (links).

This is a common trick - use the bus switch when there is a voltage domain to cross, or where it is truly necessary to translate the signal, and use very low cost links to pass the signal where that need is not present, thus saving the cost of a bus switch (an order of magnitude higher cost than the 0 ohm resistors).

Cheers

PeteS