The board considering the general interface of MCU pin need can either for the input and the input, and is 3.3 to 5.0 and 5.0 to 3.3 level conversion, then use the TXS0108E this chip,

The question is, on the single chip microcomputer is set to input, electricity at ordinary times, when you need to read pin level very is unstable, sometimes sometimes puzzling is pulled low, measured with A multimeter B port voltage is 2.5 v, occasionally A port, too, occasionally will be down to 1.9 v, in principle, on the single chip microcomputer is set to input, and then A port is 3.3, so B should is close to 5 v, why will appear this kind of unstable phenomenon?
When I was in B port to join pull-up is normal, it is said that this to cause A decline in the rate, TXS0108 internal pull-up, then why I don't add she was unstable, pull up, even without A microcontroller IO is set to the input, A port can be single chip microcomputer internal resistance on pulling it, so it should be keep close to 5.0 v B:
The chip of TI is really kill people, later can't use, waste of proofing,

CodePudding user response:

You this is automatic two-way chips, there is a note, otherwise easy to self-excited oscillation

CodePudding user response:

The input and output feet used separately, had better not use two-way circuit, with bad problem easily

CodePudding user response:

Why are you to see the internal structure is clear in la

CodePudding user response:

Drive current is small, need external pull up and down,