Multi-Level Voltage Switching Circuit Design

This paper presents the detailed design process of a custom circuit board, comprised of six switching units. Each unit integrates an optocoupler, a PNP transistor, and a resistive voltage divider to achieve the primary objective of switching a six-channel 25 V supplied circuit using control signals. The optocoupler ensures electrical isolation between the low voltage and high voltage areas, enhancing safety and reducing interference. The PNP transistor acts as a switch, controlled by the low voltage signal, while the resistive voltage divider assures the proper polarization of the transistor. The circuit is designed to support multiple single-ended voltage signaling protocols, with voltage levels ranging from 1.8 V to 5 V, making it suitable for various applications that require precise, isolated control of higher voltage loads using low-voltage signals.