Switch module with an automatic switching function according to load and method thereof

A switch module with an automatic switching function and a method for automatically switching the switch module according to the load, wherein a first comparator and a second comparator are configured to automatically determine whether the load is light or heavy according to the voltage divided by a first resistor and a second resistor and the voltage of a source resistor, thereby generating a voltage control signal. A plurality of transistors are configured to receive a gate input signal according to the voltage control signal, thereby selectively bringing a GaN transistor or a MOSFET transistor in a conducting state. In this way, the output quality and efficiency of the power supply at light and heavy loads can be improved according to the characteristics of different transistors.

BACKGROUND OF INVENTION

(1) Field of the Present Disclosure

The present disclosure particularly relates to a switch module with an automatic switching function to improve the efficiency of a power supply.

(2) Brief Description of Related Art

When the power supply responds to different application requirements, such as different loads, the output efficiency will also vary therewith. Meanwhile, when the power supply switch is turned on and off, the switching loss and the conduction loss take place, thereby making the output efficiency worse. Accordingly, how to improve the output quality and efficiency of the power supply is a problem to be resolved.

SUMMARY OF INVENTION

It is a primary object of the present disclosure to provide a switch module with an automatic switching function and a method for automatically switching the switch module according to a load, wherein a first comparator and a second comparator are configured to automatically determine whether the load is light or heavy according to a divided voltage of a first resistor and a second resistor, and a voltage of a source resistor, thereby generating a voltage control signal. A plurality of transistors are configured to receive a gate input signal according to the voltage control signal, thereby selectively bringing a GaN transistor (Gallium Nitride Field-Effect Transistor) or a MOSFET transistor (metal oxide semiconductor field effect transistor) in a conducting state. In this way, the output quality and efficiency of the power supply at light and heavy loads can be improved according to the characteristics of different transistors.

In case of heavy load, the first comparator outputs a voltage control signal to a first transistor and a second transistor. In this way, the GaN transistor can control itself in a conducting or a non-conducting state based on an external gate input signal. Due to the small switching loss and conduction loss of GaN, the efficiency of the power supply under heavy load can be improved. When the load is light, the second comparator outputs a voltage control signal to a third transistor and a fourth transistor. In this way, the MOSFET transistor can control itself in a conducting or a non-conducting state based on the external gate input signal. Due to the small switching loss of MOSFET transistor, the efficiency of the power supply under light load can be improved.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring toFIG.1, a switch module with an automatic switching function according to a load includes a control circuit1, a drive circuit2, a switch circuit3, and a source resistor Rs. The above-mentioned circuits and components can be integrated into a chip, but not limited thereto. The control circuit1is electrically connected to a circuit voltage Vcc and a source terminal S. The drive circuit2is electrically connected to a gate terminal G. The switch circuit3is electrically connected to a drain terminal D. The source resistor Rs is electrically connected to the source terminal S.

Referring toFIG.2, the control circuit1includes a first comparator11, a second comparator12, a first resistor R1, and a second resistor R2. The first comparator11includes a first inverting input terminal, a first non-inverting input terminal, and a first output terminal. The second comparator12includes a second inverting input terminal, a second non-inverting input terminal, and a second output terminal. One terminal of the first resistor R1is electrically connected to the circuit voltage Vcc while the other terminal thereof is electrically connected to the first inverting input terminal, the second inverting input terminal, and the second resistor R2. The other terminal of the second resistor R2is electrically connected to the source terminal S and the source resistor Rs. The other terminal of the source resistor Rs is electrically connected to the first non-inverting input terminal and the second non-inverting input terminal. In this way, the control circuit1can automatically determine whether the load is light or heavy according to a voltage divided by the internal resistance and a voltage generated by the external resistance, thereby generating a control signal.

Referring toFIG.2, the drive circuit2includes a first transistor Tr1, a second transistor Tr2, a third transistor Tr3, and a fourth transistor Tr4. The first transistor Tr1and the second transistor Tr2are connected in series with each other. An emitter of the first transistor Tr1is electrically connected to the first output terminal. A collector of the first transistor Tr1is electrically connected to a collector of the second transistor Tr2. An emitter of the second transistor Tr2is electrically connected to the source terminal S. A base of the first transistor Tr1and a base of the second transistor Tr2are electrically connected to the gate terminal G. The third transistor Tr3and the fourth transistor Tr4are connected in series with each other. An emitter of the third transistor Tr3is electrically connected to the second output terminal. A collector of the third transistor Tr3is electrically connected to a collector of the fourth transistor Tr4. An emitter of the fourth transistor Tr4is electrically connected to the source terminal S. A base of the third transistor Tr3and a base of the fourth transistor Tr4are electrically connected to the gate terminal G. In this way, the drive circuit2receives the input signal input from the gate terminal G according to a control signal transmitted by the control circuit1, thereby driving the switch circuit3.

Referring toFIG.2, the switch circuit3includes a first switch31and a second switch32. The first switch31and the second switch32are connected in parallel with each other. A drain of the first switch31and a drain of the second switch32are electrically connected to the drain terminal D. A source drain of the first switch31and a source of the second switch32are electrically connected to the source resistor Rs. A gate of the first switch31is electrically connected to the collector of the first transistor Tr1and the second transistor Tr2. A gate terminal of the second switch32is electrically connected to the collector of the third transistor Tr3and the fourth transistor Tr4. The first switch31is a GaN transistor. The second switch32is a MOSFET transistor. In this way, the switch circuit3controls the first switch31or the second switch32according to a driving signal transmitted by the drive circuit2.

Referring toFIG.3, the method for automatically switching the switch module according to the load includes the following steps:

Step S1of determining light/heavy load: the control circuit1automatically determines by use of the first comparator11and the second comparator12whether the load is light or heavy according to a voltage divided by the internal resistance and a voltage generated by the external resistance, thereby generating a voltage control signal. The voltage divided by the internal resistance refers to a voltage division applied to the first resistor R1and the second resistor R2by the circuit voltage Vcc. By use of the first comparator11and the second comparator12and based on the voltage divided by the second resistor R2and the voltage generated by the source resistor Rs, the control circuit1automatically controls the output of the voltage control signal from the first output terminal or the second output terminal in accordance with the change of light and heavy load.

Step S2of switching the internal switch: The drive circuit2uses the first transistor Tr1, the second transistor Tr2, the third transistor Tr3, and the fourth transistor Tr4, based on the voltage control signal, to transmit a gate input signal received from the gate terminal G to the switch circuit3to selectively turn on the first switch31or the second switch32. The first switch31is a GaN transistor, and the second switch32is a MOSFET transistor.

When the overall load of the circuit is heavy, the voltage of the source resistor Rs is greater than the voltage divided by the second resistor R2. In this case, the first comparator11outputs a voltage control signal to the first transistor Tr1and the second transistor Tr2. The first switch (GaN transistor) thus accepts the gate input signal from the external input, thereby entering into the conducting/non-conducting state. Since the switching and conduction losses of GaN transistors are small, the efficiency of the circuit under heavy load can be improved.

When the overall load of the circuit is light, the voltage of the source resistor Rs is smaller than the voltage divided by the second resistor R2. In this case, the second comparator12outputs a voltage control signal to the third transistor Tr3and the fourth transistor Tr4. The second switch (MOSFET transistor) thus accepts the gate input signal from the external input, thereby entering into the conducting/non-conducting state. Since the switching and conduction losses of MOSFET transistors are small, the efficiency of the circuit at light load can be improved.

According to the present disclosure, the control circuit1automatically determines by use of the first comparator11and the second comparator12whether the load is light or heavy according to the voltage divided by the first and the second resistor and the voltage of the source resistor, thereby generating a voltage control signal. Then a plurality of transistors is configured to receive the gate input signal based on the aforementioned voltage control signal to selectively bring the GaN transistor or the MOSFET transistor in a conducting/non-conducting state. In this way, when the circuit is under light and heavy load, the output quality and efficiency of the power supply under light and heavy load can be improved according to the characteristics of different transistors. After the implementation of the present disclosure, the output quality and efficiency of the power supply can indeed be improved.

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