AC LED array configuration switching circuit triggered by source voltage level

摘要

An LED lighting circuit where the configuration of the connection of two or more LEDs are changed from parallel to series through the use of solid state switches depending on whether the voltage level from an AC source measured by a voltage detector exceeds the sum of the forward voltages of the LEDs. Also, a method of activating LEDs in an LED array lighting apparatus involving applying a rectified alternating current to two or more LEDs, each LED having a forward bias voltage; comparing the rectified alternating current to the sum of the forward bias voltages of the two or more LEDs; and changing the circuit configuration of the two or more LEDs between a parallel connection and a series connection with respect to the rectified alternating current depending on whether the rectified alternating current exceeds the sum of the forward bias voltages of the two or more LEDs.

主权项

1. An LED array lighting apparatus powered by a rectified voltage comprising:
a pair of LEDs, each having a forward bias voltage; first and second current drivers; three solid state switches configured such that in a first state the pair of LEDs are connected in parallel to the rectified voltage and are driven by the first current driver, and in a second state the pair of LEDs are connected in series to the rectified voltage and are driven by second current driver; and a voltage detector comprising a zener diode having a zener voltage equal to or greater than a sum of the forward bias voltages of the pair of LEDs, the voltage detector being configured to:
compare the rectified voltage to the zener voltage,generate, using the zener diode, a control signal based on the comparison, andcontrol, based on the control signal, the three solid state switches to enter the first state when the control signal indicates that the rectified voltage is below the zener voltage and to enter the second state when the control signal indicates that the rectified voltage is greater than the zenor voltage.