A LED driving circuit comprising: - an input (Vbus) to receive a LED driving current, - a buffer circuit adapted to buffer said LED driving current, and - an output (LED+, LED-) to be connected to a LED and adapted to output the LED driving current to the LED, - a buffer adjustment circuit adapted to: adjust the buffer capability of the buffer circuit at a first level, in a start-up phase of the LED driving circuit when the LED driving circuit starts to receive said LED driving current, and adjust the buffer capability of the buffer circuit at a second level larger than the first level in a normal operation phase later than the start-up phase, wherein the buffer circuit comprises at least one capacitor, and the buffer adjustment circuit is adapted to adjust an effective capacitance of the buffer circuit; characterised in that the start-up phase is a phase in which a voltage on the output (LED+, LED-) and the at least one capacitor is being built and insufficient to turn on the LED, and the normal operation phase is a phase in which the voltage on the output (LED+, LED-) and the at least one capacitor has been built sufficient and turned on the LED, and the nominal light output ripple has been provided. - an input (Vbus) to receive a LED driving current, - a buffer circuit adapted to buffer said LED driving current, and - an output (LED+, LED-) to be connected to a LED and adapted to output the LED driving current to the LED, - a buffer adjustment circuit adapted to: adjust the buffer capability of the buffer circuit at a first level, in a start-up phase of the LED driving circuit when the LED driving circuit starts to receive said LED driving current, and adjust the buffer capability of the buffer circuit at a second level larger than the first level in a normal operation phase later than the start-up phase, wherein the buffer circuit comprises at least one capacitor, and the buffer adjustment circuit is adapted to adjust an effective capacitance of the buffer circuit; characterised in that the start-up phase is a phase in which a voltage on the output (LED+, LED-) and the at least one capacitor is being built and insufficient to turn on the LED, and the normal operation phase is a phase in which the voltage on the output (LED+, LED-) and the at least one capacitor has been built sufficient and turned on the LED, and the nominal light output ripple has been provided. adjust the buffer capability of the buffer circuit at a first level, in a start-up phase of the LED driving circuit when the LED driving circuit starts to receive said LED driving current, and adjust the buffer capability of the buffer circuit at a second level larger than the first level in a normal operation phase later than the start-up phase, wherein the buffer circuit comprises at least one capacitor, and the buffer adjustment circuit is adapted to adjust an effective capacitance of the buffer circuit; characterised in that the start-up phase is a phase in which a voltage on the output (LED+, LED-) and the at least one capacitor is being built and insufficient to turn on the LED, and the normal operation phase is a phase in which the voltage on the output (LED+, LED-) and the at least one capacitor has been built sufficient and turned on the LED, and the nominal light output ripple has been provided. <EOS>