| 主权项 |
1. A light emitting device control circuit with dimming function, comprising:
a dimmer circuit configured to operably generate an AC dimming voltage according to an AC voltage; a rectifier and filter circuit, which is coupled to the dimmer circuit, and configured to operably generate an input voltage according to the AC dimming voltage; a power converter circuit, which is coupled to the rectifier and filter circuit, and configured to operably operate at least one power switch therein according to a control signal to convert the input voltage to an output voltage, wherein the output voltage is supplied to a light emitting device circuit; and a headroom voltage regulation circuit, which is coupled to the power converter circuit, and configured to operably generate the control signal according to a reference value and a difference between the input voltage and the output voltage, and regulate the difference at a level corresponding to the reference value by a feedback control loop; wherein the headroom voltage regulation circuit includes:
a difference sampling circuit, configured to operably generate a headroom voltage according to the difference; anda comparison circuit, which is coupled to the difference sampling circuit, and configured to operably generate the control signal according to the headroom voltage and a reference voltage, wherein the reference voltage corresponds to the reference value. |
