MCU output open drain mode

乱世煮酒论天下

MCU output open drain mode [Copy link]

The microcontroller outputs the open-drain state. This should also be configured as output above and the circuit below can be configured as input. It is a general input and output bidirectional port.

First look at the output circuit. Assume that the chip output is high level, and it is low level after the inverter. The low level MOS tube is not turned on, and the output is in a high impedance state. At this time, it needs to be pulled up. Use a K ohm level resistor to pull up. Then the high level input reaches the port or the high level, otherwise the low level to the output is a low level.

Looking at the input circuit below, it is assumed that the input from the outside is a high level, which is flipped to a low level by the Schmitt trigger, and then flipped to a high level by the inverter, and finally sent to the inside of the chip.

qwqwqw2088

What do you want to express?

I want to popularize the knowledge of single-chip microcomputer output open-drain mode

乱世煮酒论天下

qwqwqw2088 posted on 2024-5-10 07:47 What I want to express is that I want to popularize the knowledge of single-chip microcomputer output open-drain mode

I would like to ask if my understanding is correct, especially regarding the input and output impedance of the Schmitt trigger, how to calculate it?