Switching frequency control apparatus and control method thereof
AssigneeM3 Technology Inc.
InventorsXiaoyu Xi, Bo Yang, Lou Nuo
Life of this patent
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Abstract
A switch frequency control apparatus comprises a timer coupled between a bias voltage and ground, wherein the timer comprises a first input configured to receive a ramp, a second input configured to receive a threshold voltage and an output configured to be connected to an input of a PWM circuit, wherein the output of the timer is used for setting either a constant on-time or a constant off-time of a power converter and a threshold generator coupled between the bias voltage and ground, wherein the threshold generator is configured to receive a plurality of control signals of the power converter and generate the threshold voltage based upon a duty cycle of the power converter.
Claims20
An apparatus comprising:
- a timer coupled between a bias voltage and ground, wherein the timer comprises a first input configured to receive a ramp, a second input configured to receive a threshold voltage and an output configured to be connected to an input of a PWM circuit, wherein the output of the timer is used for setting either an on-time or an off-time of a power converter, and wherein both the ramp and the threshold voltage are proportional to the bias voltage, and wherein as a result of having both the ramp and the threshold voltage proportional to the bias voltage, the PWM circuit has a constant switching frequency;
- and
- a threshold generator coupled between the bias voltage and ground, wherein the threshold generator is configured to receive a plurality of control signals of the power converter and generate the threshold voltage based upon a duty cycle of the power converter.
A method comprising:
- generating a ramp using a bias voltage of a power converter;
- generating a threshold voltage proportional to either a duty cycle or one minus a duty cycle of the power converter;
- comparing the ramp with the threshold voltage using a comparator, and
- terminating or initiating a PWM signal of the power converter based upon a comparing result generated by the comparator, and wherein both the ramp and the threshold voltage are proportional to the bias voltage, and wherein as a result of having both the ramp and the threshold voltage proportional to the bias voltage, the PWM signal has a constant switching frequency.
A converter comprising:
- a high-side switch and a low-side switch connected in series;
- an inductor connected to a common node of the high-side switch and the low-side switch;
- and
- a control apparatus configured to generate gate drive signals for the high-side switch and the low-side switch, wherein the control apparatus comprises:
- a timer for setting either an on-time or an off-time of the converter based on comparing a ramp to a threshold voltage, and wherein both the ramp and the threshold voltage are proportional to a bias voltage, wherein as a result of having the ramp and the threshold voltage proportional to the bias voltage, the gate drive signals have a constant switching frequency;
- and
- a threshold generator configured to receive the gate drive signals of the converter and generate the threshold voltage based upon a duty cycle of the converter.
Dependencies are inferred from the claim text.