Free input logic circuit - is supplied with constant volts via divider on same board and has special external terminals

摘要

The logic circuit has at least one free input connected to a constant control signal that maintains the logic in a given function state. This connection is made over a special terminal (S1) on the logic circuit's board. The constant control signal is derived from a diode (D) and resistor (W) acting as voltage divider between earth and a supply voltage (Ucc). These two components are on the same board as the logic and their control signal is connected externally to the special terminal via another special terminal (S3).