CROSS-REFERENCE TO RELATED PATENT APPLICATION

This application claims the benefit of priority to Taiwan Patent Application No. 109117052, filed on May 22, 2020. The entire content of the above identified application is incorporated herein by reference.

Some references, which may include patents, patent applications and various publications, may be cited and discussed in the description of this disclosure. The citation and/or discussion of such references is provided merely to clarify the description of the present disclosure and is not an admission that any such reference is “prior art” to the disclosure described herein. All references cited and discussed in this specification are incorporated herein by reference in their entireties and to the same extent as if each reference was individually incorporated by reference.

FIELD OF THE DISCLOSURE

The present disclosure relates to an inductor current detecting current, and more particularly to an inductor current detecting current for a power converter.

BACKGROUND OF THE DISCLOSURE

A power converter is essential for voltage adjustment and stabilization of an electronic device. Based upon different power requirements, various types of DC-DC voltage converters such as a buck converter and a boost converter have been developed. The buck converter can decrease an input DC voltage to a default voltage, and the boost converter can increase an input DC voltage. With advances in circuit technologies, both the buck and boost converters have been adjusted for different system architectures and requirements.

If a conventional power converter operates in a current controlling mode, a current value of an inductor of the conventional power converter needs to be detected. A high-side switch and a low-side switch of the conventional power converter are turned on or off according to the detected current value. In order to obtain the current value of the inductor, a resistor is additionally disposed in the conventional power converter and connected in series with the inductor. The current value of the inductor is equal to a current value of the resistor. Therefore, the conventional power converter obtains the current value of the inductor by detecting the current value of the resistor. However, the resistor not only occupies a space inside the conventional power converter, but also increases additional power consumption. In recent years, in order to meet low power consumption requirements, the resistor must have a small resistance. Under this condition, the current value of the resistor cannot be detected accurately. As a result, the high-side switch and the low-side switch cannot be accurately turned on or off. Therefore, the conventional power converter cannot achieve a fast response effect.

SUMMARY OF THE DISCLOSURE

In response to the above-referenced technical inadequacies, the present disclosure provides an inductor current detecting circuit for a power converter. The power converter includes an output inductor, an output capacitor, a high-side switch, a low-side switch, a comparator, a control circuit and a voltage divider circuit. One terminal of the output inductor is connected to a node between the high-side switch and the low-side switch. The other terminal of the output inductor is grounded through the output capacitor. The voltage divider circuit is connected to an output node between the output inductor and the output capacitor and divides an output voltage of the output node to output a feedback voltage. The comparator compares the feedback voltage with a reference voltage to output a voltage comparison signal. The control circuit turns on or off the high-side switch and the low-side switch according to the voltage comparison signal. The inductor current detecting circuit includes a charging current circuit and a synthesizing circuit. The charging current circuit includes an energy storage circuit, a current supplying circuit, a voltage comparator circuit and a current modulation controller circuit. The current supplying circuit is connected to the energy storage circuit. The current supplying circuit is configured to supply a first current signal to the energy storage circuit during a high-side conduction time and supply a second current signal to the energy storage circuit during a low-side conduction time. The voltage comparator circuit is connected to the energy storage circuit. The voltage comparator circuit is configured to obtain a reference voltage calculated by subtracting a valley voltage of the low-side switch from a peak voltage of the high-side switch and output a comparison signal according to a voltage of the energy storage circuit and the reference voltage. The current modulation controller circuit is connected to the voltage comparator circuit and the current supplying circuit. The current modulation controller circuit is configured to modulate currents of the first current signal and the second current signal to be supplied by the current supplying circuit according to the comparison signal. The synthesizing circuit is connected to the current supplying circuit. The synthesizing circuit is configured to synthesize the first current signal with the second current signal to obtain an inductor current signal, wherein each of the first current signal and the second current signal charges the voltage of the energy storage circuit to be equal to the reference voltage from zero.

In certain embodiments, the current supplying circuit includes a current source.

In certain embodiments, the voltage comparator circuit includes a comparator, an operational amplifier or an error amplifier.

In certain embodiments, the energy storage circuit includes a capacitor. A first terminal of the capacitor is connected to the voltage comparator circuit, and a second terminal of the capacitor is grounded.

In certain embodiments, the inductor current detecting circuit includes a switch component connected between the energy storage circuit and the voltage comparator circuit. The voltage comparator circuit is configured to sample the voltage of the energy storage circuit when the switch component is turned on.

In certain embodiments, the control circuit turns on the high-side switch during a working period of a high-side conduction signal. The switch component is turned on at a time point of a falling edge of a waveform of the high-side conduction signal.

In certain embodiments, the control circuit turns on the low-side switch during a working period of a low-side conduction signal. The switch component is turned on at a time point of a falling edge of a waveform of the low-side conduction signal.

In certain embodiments, the inductor current detecting circuit includes two charging current circuits, one of the charging current circuits is configured to supply and modulate the first current signal, and the other of the charging current circuits is configured to supply and modulate the second current signal.

In certain embodiments, the synthesizing circuit includes a capacitor, a first current source, a first switch component, a second switch component and a second current source. The first current source is connected to the current supplying circuit. The first current source is configured to supply a high-side charging current signal. A current of the high-side charging current signal is equal to the current of the first current signal that charges the voltage of the energy storage circuit to be equal to the reference voltage from zero. A first terminal of the first switch component is connected to the first current source. A second terminal of the first switch component is connected to a first terminal of the capacitor. A second terminal of the capacitor is grounded. A first terminal of the second switch component is connected to the second terminal of the first switch component. The second current source is connected to the current supplying circuit, a second terminal of the second switch component and the second terminal of the capacitor. The second current source is configured to supply a low-side charging current signal. A current of the low-side charging current signal is equal to the current of the second current signal that charges the voltage of the storage circuit to be equal to the reference voltage from zero. When the first switch component is turned on and the second switch component is turned off, the high-side charging current signal flows to the capacitor such that the capacitor generates a charging current signal. When the second switch component is turned on and the first switch component is turned off, the low-side charging current signal flows to the capacitor such that the capacitor generates a discharging current signal, which is synthesized with the charging current signal to form an inductor current signal.

In certain embodiments, the current modulation controller circuit includes a continuous progressive logic circuit.

As described above, the present disclosure provides the inductor current detecting circuit for the power converter, in which an additional component such as a resistor that causes unnecessary power consumption is not disposed. The inductor current detecting circuit of the present disclosure can detect a complete waveform of the inductor current signal of the power converter. When the power converter such as a buck converter is operated in a current controlling mode, the high-side switch and the low-side switch are controlled according to the complete waveform of the detected inductor current signal. Therefore, the power converter can achieve a fast response effect.

These and other aspects of the present disclosure will become apparent from the following description of the embodiment taken in conjunction with the following drawings and their captions, although variations and modifications therein may be affected without departing from the spirit and scope of the novel concepts of the disclosure.

