Power switch circuit

• US 10,693,453 B1
• Filed: 10/04/2019
• Issued: 06/23/2020
• Est. Priority Date: 08/08/2019
• Status: Active Grant

• Current Assignee: Excelliance Mos Corporation
• Original Assignee: Excelliance Mos Corporation
• Inventors: Lee, Ching-Tsan, Wu, Ke-Wei, Yang, Pei-Ting
• Primary Examiner(s): Jager, Ryan
• Application Number:
  US16/593,971
• Time in Patent Office: 263 Days
• Field of Search: 327109
• CPC Class Codes: H02M 1/08 Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
• CPC Class Codes: H02M 3/07 using capacitors charged and discharged alternately by semiconductor devices with control electrode , e.g. charge pumps
• CPC Class Codes: H03K 17/102 in field-effect transistor switches
• CPC Class Codes: H03K 17/163 Soft switching
• CPC Class Codes: H03K 2217/0054 Gating switches, e.g. pass gates

Abstract

A power switch circuit including first and second transistors, and a control circuit is provided. A first end of the first transistor serves as an input terminal of the power switch circuit. A second end of the first transistor is coupled to a node. A control end of the first transistor receives a first control voltage. A first end of the second transistor serves as an output terminal of the power switch circuit. A second end of the second transistor is coupled to the node. A control end of the second transistor receives a second control voltage. The control circuit detects a voltage of the node to determine a type of series connection between the first and second transistors, and generates the first and second control voltages to control a turned-on state of another of the first and second transistors after turning on one of the first and second transistors.

Claims

1. A power switch circuit, comprising:

a first transistor, having a first end, a second end and a control end, wherein the first end of the first transistor is configured to serve as an input terminal of the power switch circuit, the second end of the first transistor is coupled to a node, and a control end of the first transistor is configured to receive a first control voltage;

a second transistor, having a first end, a second end and a control end, wherein the first end of the second transistor is configured to serve as an output terminal of the power switch circuit, the second end of the second transistor is coupled to the node, and a control end of the second transistor is configured to receive a second control voltage; and

a control circuit, coupled to the node, the control end of the first transistor and the control end of the second transistor, wherein the control circuit detects a voltage of the node, determines a type of series connection between the first transistor and the second transistor according to the voltage of the node, and generates the first control voltage and the second control voltage according to the type of series connection, so as to start controlling a turned-on state of another of the first transistor and the second transistor after completely turning on one of the first transistor and the second transistor.

2. The power switch circuit according to claim 1, wherein the control circuit comprises:

a determination circuit, configured to detect the voltage of the node, and determine the type of series connection between the first transistor and the second transistor according to the voltage of the node to generate a determination signal; and

a control main body, coupled to the determination circuit to receive the determination signal, and generating the first control voltage and the second control voltage according to the determination signal.

3. The power switch circuit according to claim 2, wherein each of the first transistor and the second transistor is an N-type metal-oxide-semiconductor field-effect transistor, wherein if the determination signal indicates that the type of series connection between the first transistor and the second transistor is a common source type of series connection, the control main body starts switching over to the first control voltage to turn on the first transistor after switching over to the second control voltage to completely turn on the second transistor.

4. The power switch circuit according to claim 2, wherein each of the first transistor and the second transistor is an N-type metal-oxide-semiconductor field-effect transistor, wherein if the determination signal indicates that the type of series connection between the first transistor and the second transistor is a common drain type of series connection, the control main body starts switching over to the second control voltage to turn on the second transistor after switching over to the first control voltage to completely turn on the first transistor.

5. The power switch circuit according to claim 2, wherein the determination circuit comprises:

a third transistor, a first end of the third transistor being coupled to a ground terminal, a control end of the third transistor being coupled to the node;

a bias circuit, a first end of the bias circuit being coupled to a second end of the third transistor to generate a detection signal, a second end of the bias circuit being coupled to a power terminal; and

a logic circuit, coupled to the first end of the bias circuit and the second end of the third transistor to receive the detection signal, and generating the determination signal according to the detection signal.

6. The power switch circuit according to claim 2, wherein each of the first transistor and the second transistor is an N-type metal-oxide-semiconductor field-effect transistor, and the control main body comprises:

a first charge pump circuit, coupled to the determination circuit to receive the determination signal, and generating the first control voltage according to the determination signal; and

a second charge pump circuit, coupled to the determination circuit to receive the determination signal, and generating the second control voltage according to the determination signal,

wherein if the determination signal indicates that the type of series connection between the first transistor and the second transistor is a common source type of series connection, the first charge pump circuit starts generating the first control voltage to turn on the first transistor after the second charge pump circuit generates the second control voltage to completely turn on the second transistor,

wherein if the determination signal indicates that the type of series connection between the first transistor and the second transistor is a common drain type of series connection, the second charge pump circuit starts generating the second control voltage to turn on the second transistor after the first charge pump circuit generates the first control voltage to completely turn on the first transistor.

7. The power switch circuit according to claim 2, wherein each of the first transistor and the second transistor is an N-type metal-oxide-semiconductor field-effect transistor, and the control main body comprises:

a charge pump circuit, configured to generate a first pump voltage;

a delay circuit, coupled to the charge pump circuit to receive the first pump voltage, and delaying the first pump voltage to generate a second pump voltage, wherein the second pump voltage starts to be transitioned after the first pump voltage is completely transitioned; and

a switch circuit, coupled to the charge pump circuit to receive the first pump voltage, coupled to the delay circuit to receive the second pump voltage, coupled to the determination circuit to receive the determination signal, and coupled to the control end of the first transistor and the control end of the second transistor,

wherein if the determination signal indicates that the type of series connection between the first transistor and the second transistor is a common source type of series connection, the switch circuit outputs the first pump voltage to the control end of the second transistor as the second control voltage, and the switch circuit outputs the second pump voltage to the control end of the first transistor as the first control voltage,

wherein if the determination signal indicates that the type of series connection between the first transistor and the second transistor is a common drain type of series connection, the switch circuit outputs the first pump voltage to the control end of the first transistor as the first control voltage, and the switch circuit outputs the second pump voltage to the control end of the second transistor as the second control voltage.

8. The power switch circuit according to claim 7, wherein the delay circuit comprises:

a resistor, a first end of the resistor being coupled to the charge pump circuit to receive the first pump voltage, a second end of the resistor providing the second pump voltage.

9. The power switch circuit according to claim 8, wherein the delay circuit further comprises:

a capacitor, a first end of the capacitor being coupled to the second end of the resistor; and

a switch, coupled between a second end of the capacitor and a ground terminal, and controlled to be open or closed by a soft start ready signal,

wherein when the soft start ready signal indicates that the power switch circuit does not complete a soft start, the switch is in a turned-on state,

wherein when the soft start ready signal indicates that the power switch circuit does complete the soft start, the switch is in a turned-off state.

10. The power switch circuit according to claim 8, wherein the delay circuit further comprises:

a current source circuit, a first end of the current source circuit being coupled to the second end of the resistor; and

a switch, coupled between a second end the current source circuit and a ground terminal, and controlled to be open or closed by a soft start ready signal,

wherein when the soft start ready signal indicates that the power switch circuit does not complete a soft start, the switch is in a turned-on state, so that the current source circuit generates a current for generating a voltage drop between the first end of the resistor and the second end of the resistor, wherein the second pump voltage is lower than the first pump voltage,

wherein when the soft start ready signal indicates that the power switch circuit does complete the soft start, the switch is in a turned-off state, so that the current source circuit stops generating the current, and the second pump voltage is equal to the first pump voltage.

11. The power switch circuit according to claim 7, wherein the delay circuit comprises:

a diode string, an anode end of the diode string being coupled to the charge pump circuit to receive the first pump voltage, a cathode end of the diode string providing the second pump voltage; and

a switch, coupled between the anode end and the cathode end of the diode string, and controlled to be open or closed by a soft start ready signal,

wherein when the soft start ready signal indicates that the power switch circuit does not complete a soft start, the switch is in a turned-off state, so that the second pump voltage is lower than the first pump voltage,

wherein when the soft start ready signal indicates that the power switch circuit does complete the soft start, the switch is in a turned-on state, so that the second pump voltage is equal to the first pump voltage.