The voltage levels for RS-232 can vary, but based on the reference provided, it uses both 5V and 3.3V depending on the function.
According to the reference: "In these systems, an RS232 interface chip which uses the 5V supply for charge pump and driver operation and the 3V supply for receiver output levels, provides the best performance." This suggests that:
- 5V is used for the charge pump and driver operation.
- 3.3V is used for receiver output levels.
Therefore, RS-232 doesn't operate on a single voltage; different parts of the interface utilize different voltages to optimize performance.
