Other Parts Discussed in Thread: TCA9509
Tool/software:
Hello,
After taking over a project halfway through, it seems we have come unstuck by the problem everyone faces using the P82B96, the VOL specification on the S-side.
The team had already prototyped using the P82B96 to drive an I2C signal over a 10m cable and found it to be feasible with 3.3V on the S-side and 4.5V on the T/R-side. However, due to changes to the architecture elsewhere on the design, the S-side voltage has had to be reduced to 2.5V and now the VOL of the S-side is approximately equal to the 0.3xVCC VIL specification for most I2C devies. It is currently working in this configuration, but considering there is no margin and that the VOL of the S-side can go up towards 1V at lower temperatures, this solution is no longer feasible.
I notice there are a number of buffers recommended on this forum to overcome this issue and I identified the TCA9509 as the primary candidate based on our architecture. I have ordered some parts and will prototype it to validate the solution. The prototype will look something like the image below and the pullup resistor values are what we optimised for on the first prototype without the TCA9509. I imagine we will need to reoptimmise the pullups again if we find the TCA9509 is working with the P82B96.
Can someone from TI support advise if the proposed layout below is feasible or advise on any pitfalls when integrating the B-side of the TCA9509 with the S-side of the P82B96?
Thank you
