ELM334

ELM334 Garage Doorman Description The ELM334 is an integrated circuit for remotely monitoring the position of electrical contacts (on a garage door, for example) and reporting the position by way of coloured LEDs. A two-wire interface is all that is needed to convey the position of the door to two remotely located LEDs, and to also provide pushbutton control for an electric opener if desired. This circuit is able to monitor the state of one or two position sensing switches, provide debouncing of the signals, and to generate an alternating (flashing) output when the position changes. In addition, there is a separate pushbutton input that may be used to control an electric garage door opener, or possibly trigger an alarm. Several examples of how the ELM334 might be used are provided in the Example Applications section. Applications Garage door monitoring and control Remote signalling and acknowledgement Remote alarm circuits Features Low power CMOS design Wide supply range - 3.0 to 5.5 volt operation Simultaneous monitoring of three inputs Fully debounced inputs Two wire interface to LEDs Stuck button protection on the control output Pulsed control output Connection Diagram PDIP and SOIC (top view) VDD 1 RLED 2 GLED 3 PB 4 8 VSS 7 OpenSw 6 ClosedSw 5 Control Block Diagram RLED 2 GLED 3 VDD PB 4 Drive Logic Debounce Timers Debounce Timers VDD 7 OpenSw VDD 6 ClosedSw Debounce Timers Pulse Generator 5 Control ELM334DSC Elm Electronics – Circuits f...