Led lighting system, apparatus, and dimming method

An LED lighting system including a power adapter comprising a power conversion circuit and a dimmer, wherein:

• the power conversion circuit is configured to receive and then convert an external power supply signal into a power signal, which comprises a constant DC signal;
• the dimmer is configured to receive the power signal and a dimming instruction and to combine or synthesize the power signal and the dimming instruction to produce an output signal;
• and
• the dimming instruction includes a control code comprising a square wave of a specific sequence of high/low voltage levels for providing a manner of controlling an LED lamp, in order to enable the LED lamp to perform control of itself according to the manner of controlling provided by the control code in the output signal received by the LED lamp;
• and
• at least one LED lamp, wherein the LED lamp is configured to receive the output signal and to light up and adjust the luminance and/or color temperature of the LED lamp according to the control code in the received output signal.