We are using PCA9509 chipset on my custom board. The VOL level of the chipset port A 3.5V.
As per datasheet page# 8, it should be 0.2V typical & <0.3V Max, If VCCA is >1.35V.
Our VCCA is 1.8V & VCCB is 3.3V.
Find below schematic for your reference.
Following things tried:
1. Tried weak pullups. Changed 10k resistor to on U41 A1 port to 20k.
2. Check V input on U41 B1 port to ensure the VIL level match for B port. It is matching, the signal on port B reflects on port A.
Please advice the solution.