From the datasheet, the power supply for this Multiplexer is from 3.3V to 5V.
But when I connect the 3.3V, it doesn’t work. When I connect 5V, it can work for 1 piece only, another piece doesn’t work. But half day later, when I test it again, all of them cannot work under 5V, it only works when I connect to the power supply with voltage above 5.7V.
Could you help to check the reason? Below is the link of the product, thanks!
DFR0576 DFRobot | Development Boards, Kits, Programmers | DigiKey
Checking one this. Will let you know when I have the answer.
A schematic for the board can be found here, and the datasheet for the target IC here.
Increasing the supply voltage above about 5V would cause the on-board pull up voltage to fall below the valid logic-high range; the board would not be expected to function under these conditions.
Some kind of error in the connected circuits is the most likely explanation. I would suggest measuring the waveforms directly using an oscilloscope as a step toward understanding the problem.
