Driver circuit for driving light emitting device

A light emitting device driver circuit, which is configured to operably supply a load current to a light emitting device so as to drive the light emitting device;

• the light emitting device driver circuit comprising:
• a power conversion circuit, which is configured to operably convert an input voltage to an output voltage at an output terminal according to an error amplification signal and supply the load current to the light emitting device, wherein the light emitting device is coupled between the output terminal and a load node;
• an error amplifier circuit, which is configured to operably generate the error amplification signal according to a difference between a first reference voltage and a feedback signal;
• a sample-and-hold circuit, which is coupled between a terminal of the error amplifier circuit which receives the feedback signal and the load node;
• a load current generation circuit, wherein the load current generation circuit, the sample-and-hold circuit and the light emitting device are commonly coupled to the load node, the load current generation circuit being configured to operably determine a first current level of the load current during an enable phase and the load current generation circuit being configured to operably determine a second current level of the load current during a disable phase;
• and
• a feed-forward capacitor, which is coupled between the output terminal and the terminal of the error amplifier circuit which receives the feedback signal;
• wherein, when the light emitting device driver circuit operates in the disable phase, the sample-and-hold circuit connects the feedback signal with a second reference voltage, whereas the sample-and-hold circuit disconnects the feedback signal from the load node, whereby at a transition time point when a transition takes place from the disable phase to the enable phase, the feed-forward capacitor samples a sample voltage;
• wherein, when the light emitting device driver circuit operates in the enable phase, the sample-and-hold circuit disconnects the feedback signal from the second reference voltage, whereas the sample-and-hold circuit connects the feedback signal with the load node, whereby the feed-forward capacitor holds the sample voltage, so that during a predetermined current elevation period following the transition time point, there is a difference between the first reference voltage and the feedback signal, and the difference is large enough to cause the load current to be raised to the first current level within the predetermined current elevation period.