1. An LED lamp comprising a driving circuit controlled by a switch during use, wherein the driving circuit comprises:a dimming controller having a switch state monitoring port and a power supply port, wherein the power supply voltage gradually decreases after the switch is turned off, and when the switch is turned on again, if the power supply voltage is between a first set value and a second set value, the dimming controller outputs a driving signal with the same value as the driving signal when the switch is off, so that the current flowing through the LED light source remains unchanged; when the supply voltage is lower than the second set value, the dimming controller outputs a dynamically changing driving signal to cause current flowing through the LED light source gradually changing from a first extreme value to a second extreme value; and
a power conversion unit, configured to receive the driving signal and provide energy for the LED light source;wherein the dimming controller comprises:a dimming trigger module outputting a corresponding trigger signal according to the switch state;
an undervoltage detection module for detecting a supply voltage of the input dimming controller;
a reference signal generator outputting a reference signal having a fixed potential or a gradient change according to magnitude of the power supply voltage at a time when the switch is on;
a PWM pulse width modulation module that is configured to receive the reference signal and synthesize the PWM pulse signal.