PhotoMOS® Optically-Isolated Relays are quite different from standard electromechanical relays and have a variety of applications including test and measurement equipment, industrial control, and security. PhotoMOS Relays inherently have a limited DC load, however, by changing the output terminal connections, 6-Pin DIP and SOP type PhotoMOS Relays can withstand a higher load capacity. Using the Panasonic AQV2 Series PhotoMOS Relay as an example, this article will walk you through how to increase load capacity by slightly modifying your design’s output circuit.
The PhotoMOS Relay is composed of input pins that are connected to a light-emitting diode (LED) in the upper portion of the relay. When a current flows through the LED, it emits infrared light. Panasonic’s AQV2 PhotoMOS employs two MOSFETs to switch the output, which is connected to the source terminal (Pin 5). Figure 1 displays three output connections available for a DC load.