A driver circuit for a LED lighting device, comprising: an AC power supply, a dimmer defining a dimming position, a transformer, and a dimming control circuit, the dimming control circuit comprising: - a filtering unit, configured to filter a voltage signal from the transformer and to output the voltage signal after filtering, - a rectifying unit, configured to receive a voltage signal from the filtering unit and to rectify the filtered voltage signal into a DC signal; - a boost converter unit, configured to receive and boost the DC voltage signal from the rectifying unit to provide a boosted voltage according to a required DC voltage; - a voltage feedback control circuit unit, configured to control the boosted voltage from the boost converter unit; - a buck converter unit, configured to convert the boosted voltage into a voltage and a current required by the LED lighting device. - a control-signal conversion unit, connected to the boost converter unit, the voltage feedback control circuit unit, and the buck converter unit, respectively, wherein an amount of the current of the LED lighting device is related to the dimming position of the dimmer and related to a voltage at a point corresponding to the DC voltage after being boosted by the boost converter unit, wherein the control-signal conversion unit is configured to automatically adjust an amount of a current required by the buck converter unit, according to the voltage at the point corresponding to the DC voltage after being boosted by the boost converter unit characterized in that (i) the control-signal conversion unit is configured to sample the voltage at the point corresponding to the DC voltage after being boosted by the boost converter unit to provide a sampled voltage signal, (ii) the control-signal conversion unit includes a filtering process circuit and an analog operational amplifier and is configured to convert the sampled voltage signal by removing high-frequency interference and low-frequency disturbance into a clean analog control-voltage signal, which clean analog control-voltage signal is transmitted to the buck converter unit. - a filtering unit, configured to filter a voltage signal from the transformer and to output the voltage signal after filtering, - a rectifying unit, configured to receive a voltage signal from the filtering unit and to rectify the filtered voltage signal into a DC signal; - a boost converter unit, configured to receive and boost the DC voltage signal from the rectifying unit to provide a boosted voltage according to a required DC voltage; - a voltage feedback control circuit unit, configured to control the boosted voltage from the boost converter unit; - a buck converter unit, configured to convert the boosted voltage into a voltage and a current required by the LED lighting device. - a control-signal conversion unit, connected to the boost converter unit, the voltage feedback control circuit unit, and the buck converter unit, respectively, (i) the control-signal conversion unit is configured to sample the voltage at the point corresponding to the DC voltage after being boosted by the boost converter unit to provide a sampled voltage signal, (ii) the control-signal conversion unit includes a filtering process circuit and an analog operational amplifier and is configured to convert the sampled voltage signal by removing high-frequency interference and low-frequency disturbance into a clean analog control-voltage signal, which clean analog control-voltage signal is transmitted to the buck converter unit.