Automated LED Testing and Control | Cypress Semiconductor
Automated LED Testing and Control
Light Emitting Diodes (LEDs) are used in most applications. The problem is that unlike most modern ICs there is not a simple way to test in manufacturing that they have been assembled properly. The majority of system manufacturers test LEDs by visual inspection. This is highly prone to error since it is entirely dependent on the individual operator to detect the failure in a highly repetitive environment. These primary failures manifest as opens or shorts and can be tested automatically through electrical measurements of the actual LED. A basic method for electrical testing is described showing how discrete components can be used to take voltage measurements across an energized LED and then used to determine if it is electrically "good". Basically this takes a voltage measurement across an energized LED and compares it against a "good" value to determine any problem LEDs. The primary limitation of this approach is the component count which is required to implement the design for high LED count boards. This article illustrates how to automate testing of LEDs under multiple configurations, including an approach requiring only a single component testing multiple LEDs without requiring additional discrete elements. This provides designers with the capability to not only automate the testing of LEDs, but also test at any time simply by repeating the measurements. To view more on this topic, click the download link above.