What type of device helps in limiting the dark current in LED applications?

The LED driver is designed to control the current flowing through an LED, ensuring that the device operates efficiently and with optimal brightness. One of its key functions is to limit the dark current, which is the small current that flows through the LED when it is not actively emitting light (i.e., when it is in a non-conducting state). By regulating the current and providing the appropriate voltage and current needed for the specific LED configuration, the driver prevents excessive dark current, which can lead to reduced performance and lifespan of the LED.

In contrast, other devices listed do not specifically serve this purpose. A thermal overload relay is primarily used for protecting circuits from overheating, rather than managing dark current in LEDs. A ballast is typically associated with fluorescent lamps and helps stabilize the current; it is not used in conjunction with LEDs. Finally, a switch simply controls the flow of electricity to a circuit but does not regulate current in the way an LED driver does. Thus, the LED driver is the appropriate device for limiting dark current in LED applications.