Detecting LED Lamp Failure Using a 319RSM
Description
The 319RSM (resistive sense module) may be configured to measure either resistance or voltage. Because it has the ability to measure low voltages at a high resolution (10-bit) a circuit can be configured to enable it to measure if an LED lamp has failed or become open circuit.
The following design will produce a logic high output when the lamp is active and logic low when it is off/disconnected/open circuit.
Circuit Diagram
The following circuit enables E-Plex to monitor failure of LED lamps that draw 50mA or more current during normal operation. The LED lamp will have an internal current limiting device such as a resistor or constant current driver to ensure the LED is driven at the correct voltage (this is not shown in the diagram below).
All resistors are 1/4 watt 5% carbon film resistors. This configuration is good for LED lamps that draw up to 80mA. Any greater than this and the power rating of the 33 ohm resistor should be increased.
E-Logic Configuration
Schematic
Place the “Resistive Digital Module v2.05” version that has the digital comparator output onto your design.
Unique Properties
Set the unique properties as below:
