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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 of the data sheet.


  • Garage door monitoring and control
  • Remote signalling and acknowledgement
  • Remote alarm circuits


  • 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 or SOIC, top view )
ELM334 connection diagram

Block Diagram

ELM334 block diagram


The ELM334 data sheet (ver C, 52K):

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Quantity Pricing

The following are the unit prices, as you vary the quantity purchased:






All prices are in Canadian dollars. We use the total number purchased (ELM334P + ELM334SM) for the calculation.


Select the desired integrated circuit package type, then the quantity desired, before adding it to your shopping cart. Quantity discounts will be applied as appropriate.

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