RS232 Break Detector


The ELM626 is a complete circuit for detecting break signals on RS232 lines, in an 8 pin package. The circuit is similar to the ELM627 except that an output pulse is not generated on power-up.

The threshold for break signal detection is user selectable, allowing the circuit to respond to a transmitted null character, <ctrl>@, at various baud rates. This provides a convenient means for the remote triggering of this circuit by simply shifting to a lower baud rate and sending a null byte.

Two complementary high current outputs are provided by the ELM626, so that further buffering is not usually required. The output signal can be selected to be either a continuous one (following the TxD input line) or else a 100ms pulse output.

No external components are required for circuit operation other than possibly a current limiting resistor, as all timing references are generated internally.


  • Remote resetting of RS232 devices
  • Edge triggered one-shot circuits
  • Digitally controlled sequencing schemes
  • Watchdog type signal monitors


  • Low power CMOS design – typically 1mA at 5V
  • No external timing elements required
  • Complementary outputs
  • Digitally controlled threshold timing
  • Selectable output duration
  • High current drive outputs – up to 25 mA

Connection Diagram

( PDIP or SOIC, top view )
ELM626 connection diagram

Block Diagram

ELM626 block diagram


The ELM626 data sheet (ver A, 26K):

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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 (ELM626P + ELM626SM) 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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