Hi team,
My customer use the part in the switch. And below is the diagram.
The signal is from the A port to B port.
And they find the B port signal has a ringing in the falling edge.(show as below).
So please help to answer below questions:
1. What may be the cause for the ringing?
2. Customer tried to increase the 0 ohm resister, but it seems a little improvement, not much. So do you have any suggestion for eliminating the ringing?
Lacey
Thanks a lot!
Hey Lacey,
I thought you might like to see my simulation showing what might be going on. Here I have 3 identical output drivers with 3 different loads. The first two have transmission lines as part of the load, and the third has the TL removed.
The key thing to take away from this is that increasing the inductance on the line will increase ringing. A 50 ohm transmission line typically has 100pF and 250nH per meter (the ratio is controlled by the equation Zo = sqrt(L/C) ). I suspect something like this is happening in your customer's circuit.
I also included my Tina-TI simulation file if you want to show them directly.
Hi Emrys,
Thanks a lot for your effort!!
Now, customer tried the change the value as below:
Using the value, customer can solve the vibration problem.
But now customer's concern is that because the port B is OD port, they need to put a pull up resistor. In their current circuit, they connect the pull up resistor on the left side of the series resistor.
1. Will it cause other problem? such as affect the function of our part?
2. What's the recommend value for the pull up resistor according their current circuit?
Lacey
Thanks a lot!
