Quiescent Current can be defined as the amount of current used by an LED driver when in a Quiescent state. The Quiescent state can be defined as any period of time when the driver is in either a no-load or non-switching condition, however, is still enabled. So, the quiescent current of an LED driver, often referred to as "standby current," is the current that flows through the LED driver circuit when it is in a non-active or idle state, meaning when it is not actively driving the LEDs. In other words, it is the current consumed by the LED driver itself to maintain its operational readiness.

The quiescent current is typically very low, as the LED driver should be designed to be energy-efficient when not actively powering the LEDs. This is important for applications where power efficiency and low energy consumption are critical, such as battery-operated devices, energy-saving lighting systems, and other electronics.

When the LED driver is not actively driving the LEDs, it remains in a standby or idle state, ready to respond to control signals or user input to activate the LEDs quickly. The quiescent current ensures that the driver can make a transition from standby to active mode without significant delay.

Keeping the quiescent current low helps improve the overall energy efficiency of the LED driver system. Lower quiescent current means less power is wasted when the LEDs are not in use.

The specific value of the quiescent current can vary depending on the design and efficiency of the LED driver. In many cases, it may be in the microampere (µA) or milliampere (mA) range and modern LED driver designs aim to minimize this current as much as possible to meet energy efficiency standards and requirements.