Part Number: TCA6408A
Dear Team,
As discussed earlier in the E2E forum, we have used the TCA6408ARGTR as a GPIO expander, as shown in the circuit below.
In the above circuit, we are able to control all the GPIO ports (P0–P7) as expected. However, when we configure P1 as LOW, instead of observing 0 V, we are measuring approximately 1.8 V at the P1 output.
The PS_1V8_F_RESET signal is generated by the FPGA and passes through the ADG3308BCBZ-1-RL7 level translator, translating the signal from 3.3 V to 1.8 V. We have provided local pull-up resistors for this signal on both sides of the level translator, with the corresponding pull-ups connected to 1.8 V and 3.3 V, respectively.
As part of our troubleshooting, we removed the 1.8 V pull-up resistor and repeated the test. However, we are still observing approximately 1.8 V when P1 is configured as LOW.
Could you please review the above circuit and advise us on the possible cause of this behavior and the recommended solution at your earliest convenience?
The circuit image is attached for your reference.
Thanks in advance for your support.
Best Regards,
Abhishek
