Bounce Free Switches and Debouncer ICs for Digital Electronics


The typical mechanical switch in use today was not designed for high-speed digital applications. Its original purpose was for high-current AC loads, such as lighting, heating or motor on/off control, where contact bounce was not a problem for the circuit designer to deal with. With the advent of high speed computers and microcontrollers, functional flaws in the operation of the legacy switch have made life difficult for digital circuit designers. Until now, the industry has ignored the differences between the two totally different types of applications for switches. The LogiSwitch Switch was created specifically to fill this need for high-speed digital circuits.

The LogiSwitch concept uses a mechanical SPDT switch front end interfaced to an embedded CMOS cross-coupled nand circuit to provide a clean, fast, fully debounced output with a typical propagation delay of 150ns at V+ of 5 volts.  Momentary output selections are Normally High (NH) or Handshake (HS). An additional third selection is provided: a fully debounced Toggle operation (TG) which changes state each time the switch is pressed. These three selections are provided for the digital circuit designer’s choice in every LogiSwitch product. There is no longer a need to inventory both momentary and push on/push off, or alternate action type switches. The handshake selection provides a means to eliminate the awful time-wasting exit polling by giving control of terminating the cycle to the program, rather than waiting until the switch is physically released.


Initial LogiSwitch product release consists of a series of momentary panel-mount pushbutton switches to meet the lion’s share of digital uses and a beginning line of subminiature limit switches. Future LogiSwitch products will include a variety of functional switch types to meet every application the digital circuit designer will ever need. Users are encouraged to recommend other switch types for the LogiSwitch Advantage.


The LogiSwitch concept is ideal for the numerous limit switches used in industrial automation and robotics circuits to provide positional feedback, where time is always of the essence. Getting bogged down with software debounce delay routines, or populating your control circuit with debounce hardware are no longer necessary. With the LogiSwitch alternative, contact bounce is a thing of the past.