Hello everyone
I have the following issue with the GPIOs of a LTC6811-1 in conjunction with an analog multiplexer ADG1606:
I use four of the five GPIOs of the LTC6811-1 as digital outputs (GPIO2 to GPIO5) to control the 16-channel analog multiplexer ADG1606. the fifth GPIO of the LTC6811-1 (GPIO1) is used as analog input for the up to 16 temperature sensors that are connected as voltage divider with a regular resistor to the analog multiplexer. The issue is now that the ouput voltage of the analog multiplexer is permanent at around 7V, when I do not pull the GPIO1 down at GND, although the supply voltage of the analog mux is (should be, see later in this issue description) 5V. When I pull down the GPIO1 to GND, the output voltage of the analog multiplexer is at the correct value of the voltage from the voltage divider with the temperature sensor (the output of the analog multiplexer is connected to the GPIO1 via a series resistor). It seems to me, that the GPIOs of the LTC6811-1 are pulled up to some internal voltage, when they're not explicitly pulled down to GND, since I have no other explanaiton, where the 7V could come from.
This peculiarity led to another issue:
Since the analog multiplexer works in a bidirectional manner, the 7V, which seemed to come from the LTC6811-1 are sourced back via the voltage dividers with the temperature sensors to the supply voltage of the analog multiplexer and lift the supply voltage to also around 7V (a bit less than the 7V at the GPIO1, which seems indeed to indicate, that the LTC6811-1 sources the 7V back), which killed one of the supply ICs.
Has anyone had similar issues or some hints for me? Thank you in advance for your answers.
Kind regards
Mane
