For 12v dimmable led power supply to achieve dimming, its 12v dimmable led power supply must be able to detect the variable phase angle output of the triac controller in order to adjust the current flowing to the LED. It is very difficult to do this while maintaining the dimmer working properly, which often results in poor performance. The problem can be manifested as flicker and audio noise. These undesirable phenomena are usually caused by factors such as false triggering or premature turning off of the triac The root cause of the false trigger is the current oscillation when the triac r is turned on.

When the triac is turned on, the AC mains voltage is applied to the LC input filter of the LED lamp power supply almost instantaneously. The voltage step applied to the inductor will cause oscillation. If the dimmer current is lower than the triac holding current during the oscillation period, the triac will stop conducting. The triac trigger circuit is charged, and then the triac is turned on again. This kind of irregular multiple restarts of the triac can make the 12v dimmable led power supply produce audio noise or LED flicker.

For Triac 60W dimmable led power supply,  the maintenance current required to maintain conduction is usually between 8mA and 75mA. Incandescent lamps are easier to maintain this current level, but for LED lamps that consume only 10% of the equivalent incandescent lamp, the current can be reduced to below the triac holding current, causing the triac to turn off prematurely. This will cause flicker or limit the dimmable range.