Opendrainopencollectortyyppisiä

Opendrainopencollectortyyppisiä refers to a type of electronic output stage commonly found in integrated circuits. The term itself is a combination of "open-drain" and "open-collector," which describe the fundamental behavior of the output transistor. In this configuration, the output transistor is not directly connected to a power supply rail (like Vcc or Vdd) or ground. Instead, one end of the transistor is connected to the output pin, and the other end is left "open" or connected to either the power supply or ground through an external component, typically a pull-up or pull-down resistor.

When the output transistor is turned on, it connects the output pin to either ground (in the case of an open-collector output) or the power supply (in the case of an open-drain output). When the transistor is turned off, it effectively disconnects the output pin, leaving it in a high-impedance state. This is where the external resistor comes into play, pulling the output voltage to a defined high or low state when the transistor is off.

The primary advantage of opendrain/opencollector outputs is their flexibility. They allow multiple devices with such outputs to be connected together on the same signal line. This configuration is often used in bus systems and for implementing wired-AND or wired-OR logic functions. It also simplifies level shifting between different voltage domains, as the external pull-up resistor can be chosen to match the voltage of the receiving device. Common applications include I2C communication protocols and general-purpose digital I/O pins that need to be configured for various purposes.