Other Parts Discussed in Thread: SN74AHC541
Good morning,
I have a question about pull up resistor values and how to limit the current.
I see the table in the datasheet and the formula Rpu=(Vpu-0.35)/0.015A to limit it to 15mA.
My questions,
Let's assume, I have a signal which is an Input to B1 pin with a 5V pull up and it is an output to port A1 pin. And VREFB is 5V and VREFA is 3.3V.
1-) Do I need to add any pull up on A pins or the only pull up which is added to B pins would be enough? Example: To set the current to 15mA, then Pup B1 pin with 310 ohm with a 5V to set the current to 15mA. Correct?
2-) What if I need an initial state to on port A and I also want to add a pull up there. Assume I have 10k pull ups on both port A and port B. Signal is going through from Port B to Port A. Vref B is 5V and Vref A is 3.3V. What would be the current that the driver needs to drive(set current)?
I am a bit confused, happy to hear your feedback.
Best regards
Onur