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PCA9509 VOL level

Question asked by Ritesh Patel on Jul 19, 2019
Latest reply on Aug 1, 2019 by Lisette Paulina Lozano Gomez



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.