The invention discloses a control method and a controller. The control method is applied to a
silicon controlled LED dimming power supply, and in each
work cycle of the power supply, the control method comprises the following steps of: a
voltage conversion step, specifically, converting a
voltage VB representing the magnitude of a
bus voltage into a differential voltage V1; a zero-crossing detection step, specifically, detecting the voltage VB, and outputting a zero-crossing
signal Vz after detecting that the voltage VB is reduced from high to low; a counting step, specifically, receiving the differential voltage V1, performing resetting when receiving the differential voltage V1, starting counting through a timing reference, and outputting a real-time counting value; a conduction angle detection step, specifically, receiving the zero-crossing
signal Vz, and when receiving the zero-crossing
signal Vz, collecting a counting value output at the moment in the counting step, and recording the counting value as Count3; an LED
current threshold value adjusting step, specifically, generating a reference voltage according to control signals; and a
constant current step, specifically, adjusting the magnitude of power supply output
driving current according to the reference voltage. According to the control method, in each
work cycle of the power supply, the control signals are alternately output according to a first rule or a second rule. According to the control method and the controller of the invention, the stroboflash of an LED can be avoided, and dimming can be realized at the same time.