Abstract: An electric-shock protection circuit that incorporates a PWM start-up control circuit for controlling the start-up of the PWM controller IC. When an electric-shock current test is conducted, the PWM start-up control circuit prevents the starting up of this PWM controller IC. This circuit is realized by resistors, capacitors and switches. In order to achieve protection, the switches perform an operation that different electric paths are activated for a supply voltage condition of around 90-149Vac and another condition of around 150-264Vac. The circuit disclosed in this invention: can be used in the electric-shock current test with a wide range of supply voltage; can ensure that the peak value of the shock current is lower than the safety threshold for human bodies; and can solve the problem encountered in carrying out the test of Standard UL935 where one end of the LED light tube is connected to the electric grid.

Abstract: An RCD transient absorption circuit, having a first port and a second port, the RCD transient absorption circuit comprising a first resistor, a capacitor and a diode, wherein: the first resistor is connected in parallel to the capacitor, and resultant parallel connection of which is connected in series to a diode; one end of the resultant parallel connection of the first resistor and the capacitor is connected to a cathode of the diode; another end of resultant parallel connection is the first port of the RCD transient absorption circuit; and the second port of the RCD transient absorption circuit is an anode of the diode; the RCD transient absorption circuit further comprises a power-trimming device connected in parallel to the first resistor and the capacitor.

Abstract: An LED current PWM dimming module comprising: an input voltage regulator for regulating the constant direct current supplied by the LED driver power supply in order to maintain a fixed and stable supply voltage source to a timer-oscillator and a DC-DC buck converter; the timer-oscillator for generating a repetitive square wave electrical output to be fed to the DC-DC buck converter; and the DC-DC buck converter for producing a driving pulse-width-modulated (PWM) current output to power one or more LEDs from the repetitive square wave electrical output; wherein the timer-oscillator receives a control signal from an external dimming controller and adjusts the repetitive square wave electrical output frequency and duty cycle accordingly; and wherein the driving PWM current output frequency and duty cycle being varied in an open-loop manner.

Abstract: An integrated system for supplying direct current and brightness dimming for light emitting diodes (LEDs) comprising: an LED driver power supply for supplying a constant direct current; an array of one or more LEDs; and an integrated programmable LED current pulse width modulation (PWM) dimming controller; wherein the integrated programmable LED current pulse width modulation (PWM) dimming controller comprising: a front control panel for controlling the brightness of the array of one or more LEDs; and an LED current PWM dimming module.