Switching frequency controller, voltage converter, and method for controlling switching frequency

A switching frequency controller comprising:

• a frequency divider, configured to generate a divisional signal having a divisional frequency according to a target signal having a target frequency, wherein the target frequency is 2N times of the divisional frequency, and wherein N is a positive integer;
• a frequency detector coupled to the frequency divider, the frequency detector being configured to
• receive
• the divisional signal generated by the frequency divider, and
• a switching control signal generated by a control signal generator, and calculate a number of periods of the switching control signal that pass by during
• each cycle of the divisional signal,
• wherein each cycle of the divisional signal comprises an on-time and an off-time having different potentials, and
• wherein the number of periods is represented by (N+1) bits;
• an accumulation counter coupled to the frequency detector, the accumulation counter being configured to
• set an indication value as a starting value during an initial stage, and
• increase or decrease the indication value by a predetermined amount according to a most significant bit of the number of periods;
• and
• an on-time controller coupled to the accumulation counter, the on-time controller being configured to adjust a parameter of the control signal generator according to the indication value so as to adjust an on-time length of the switching control signal;
• wherein:
• when the most significant bit of the number of periods is 1, the accumulation counter increases the indication value by the predetermined amount, and when the most significant bit of the number of periods is 0, the accumulation counter decreases the indication value by the predetermined amount.

A method for controlling a switching frequency of a switch, the method comprising the steps of:

• using a control signal generator to generate a switching control signal to control the switch, wherein each cycle of a divisional signal comprises an on-time and an off-time having different potentials;
• generating the divisional signal having a divisional frequency according to a target signal having a target frequency, wherein the target frequency is 2N times of the divisional frequency, and wherein N is a positive integer;
• calculating a number of periods of the switching control signal that pass by during each cycle of the divisional signal, wherein the number of periods is represented by (N+1) bits;
• setting an indication value as a starting value during an initial stage;
• increasing or decreasing the indication value by a predetermined amount according to a most significant bit of the number of periods;
• and
• adjusting a parameter of the control signal generator according to the indication value so as to adjust an on-time length of the switching control signal;
• wherein a frequency of the switching control signal is effectively controlled within a preset range close to the target frequency.