DCR sense for a COT power converter
AssigneeRichtek Technology Corporation
InventorsCheng-De Tseng, Chia-Jung Lee
Life of this patent
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Abstract
A DCR sense scheme is provided to sense the inductor current of a COT power converter. The DCR sense is implemented by using the direct current resistance of the output inductor of the COT power converter, and thus eliminates the ESR limitations on the type of output capacitors for stability concern. A quick response mechanism is further incorporated in the COT power converter to speed up the transient response of the COT power converter.
Claims14
A constant on-time power converter, comprising:
- an output capacitor, an output inductor and a switching circuit being configured such that the switching circuit is controlled by a control signal to modulate an inductor current flowing through the output inductor and charging the output capacitor to generate an output voltage;
- and
- a sensing circuit, including:
- a first resistor connected between an end of the output inductor and a node;
- a sense capacitor connected between the node and the other end of the output inductor such that the combination thereof with the first resistor senses the inductor current to generate a feedback signal to determine the control signal;
- a second resistor shunt to the sense capacitor;
- and
- a third resistor connected between the node and a ground terminal such that the combination thereof with the second and third resistors determines a direct current level of the output voltage.
A constant on-time power converter, comprising:
- an output capacitor, an output inductor and a switching circuit being configured such that the switching circuit is controlled by a control signal to modulate an inductor current flowing through the output inductor and charging the output capacitor to generate an output voltage;
- a sensing circuit connected to the output inductor, sensing the inductor current to generate a feedback signal;
- and
- a quick response mechanism connected to the sensing circuit, triggering a quick response signal according to the feedback signal and the output voltage to speed up the transient response of the power converter;
- wherein the quick response mechanism comprises:
- a first circuit providing a first signal which is a function of the output voltage;
- a second circuit connected to the first circuit, generating a second signal according to the first signal and a reference voltage;
- a third circuit connected to the second circuit, generating a third signal according to the second signal and the reference voltage;
- and
- a fourth circuit connected to the third circuit, triggering the quick response signal according to the third signal and the feedback signal.
A control method for a constant on-time power converter including an output capacitor, an output inductor and a switching circuit being configured such that the switching circuit is controlled by a control signal to modulate an inductor current flowing through the output inductor and charging the output capacitor to generate an output voltage, the control method comprising the steps of:
- sensing the inductor current to generate a feedback signal;
- providing a first signal which is a function of the output voltage;
- generating a second signal according to a difference between the first signal and a reference voltage;
- determining a third signal according to the second signal and the reference voltage;
- and
- comparing the third signal with the feedback signal to trigger a quick response signal to speed up the transient response of the power converter.
Dependencies are inferred from the claim text.