Low-power solid-state relay with protection circuit

Abstract

This invention discloses a low-power solid-state relay with protection circuitry, comprising a first isolation circuit, a second isolation circuit, a soft-start circuit, a first switching switch, a second switching switch, a first output drive circuit, a second output drive circuit, and a current sampling circuit. The first and second isolation circuits respectively receive and convert input signals into output signals. The soft-start circuit generates control signals within and outside the startup voltage delay time, causing the switching switch to turn on according to the received control signal, allowing the output signal to further power the electrically connected output drive circuit through the switching switch. The current sampling circuit captures the current signal from the output drive circuit, allowing the current signal to flow through the first and second output drive circuits, which are designed with multi-source electrodes and have different channel width-to-length ratios, reducing output power consumption.

Claims

1. A low-power solid-state relay with a protection circuit, comprising: a first isolation circuit for receiving and converting a first input signal into a first output signal; a second isolation circuit for receiving and converting a second input signal into a second output signal; wherein a signal level of the first output signal is lower than a signal level of the second output signal; a soft-start circuit for generating a first control signal when the delay time is less than a start-up voltage delay time, and generating a second control signal when the delay time is greater than or equal to the start-up voltage delay time; a first switching switch electrically connected to the first isolation circuit and the soft-start circuit, and turned on according to the first control signal; a second switching switch electrically connected to the second isolation circuit and the soft-start circuit, and turned on according to the second control signal; a first output drive circuit electrically connected to the first isolation circuit through the first switching switch when the first switching switch is turned on, and electrically connected to the second isolation circuit through the second switching switch when the second switching switch is turned on. A second output driving circuit is electrically connected to the first output driving circuit. When the first switching switch is turned on, it is electrically connected to the first isolation circuit through the first switching switch, and when the second switching switch is turned on, it is electrically connected to the second isolation circuit through the second switching switch. A current sampling circuit is electrically connected to the first output driving circuit and the second output driving circuit to capture a current signal output by the first output driving circuit and the second output driving circuit. The first output driving circuit includes a first power MOSFET, and the second output driving circuit includes a second power MOSFET. The first power MOSFET has a first channel width-to-length ratio and a second channel width-to-length ratio, which is 1:n. The second power MOSFET has a third channel width-to-length ratio and a fourth channel width-to-length ratio, which is 1:n, where n is a positive number.

2. The low-power solid-state relay with protection circuitry as described in claim 1, wherein the first power MOSFET comprises a first silicon power MOSFET, a first silicon carbide power MOSFET, or a first gallium nitride power MOSFET, and the second power MOSFET comprises a second silicon power MOSFET, a second silicon carbide power MOSFET, or a second gallium nitride power MOSFET.

3. The low-power solid-state relay with protection circuitry as described in claim 1, wherein the soft-start circuitry includes a timing circuitry, the timing circuitry including a charging capacitor, receiving a control voltage to generate a capacitor voltage; wherein the start-up voltage delay time of the soft-start circuitry is set according to the magnitude of the capacitor voltage.

4. A low-power solid-state relay with protection circuitry as described in claim 1, wherein the soft-start circuitry includes a timing circuit, a first comparator, a first reverse gate, and a second reverse gate. The timing circuitry includes a charging capacitor, receives a control voltage, and generates a capacitor voltage based on the control voltage. A first input terminal of the first comparator is electrically connected to the charging capacitor to receive the capacitor voltage. A second input terminal of the first comparator receives a buffer voltage. An output terminal of the first comparator is electrically connected to an input terminal of the first reverse gate. An output terminal of the first reverse gate is electrically connected to an input terminal of the second reverse gate and the first switch. An output terminal of the second reverse gate is electrically connected to the second switch. When the capacitor voltage is less than the buffer voltage, the first comparator and the first reverse gate generate the first control signal to the first switch. When the capacitor voltage is greater than or equal to the buffer voltage, the first comparator, the first reverse gate, and the second reverse gate generate the second control signal to the second switch.

5. The low-power solid-state relay with protection circuitry as described in claim 1, further comprising: an overcurrent protection circuit, one input terminal of which is electrically connected to the first output drive circuit and the second output drive circuit, and generating a high-level signal when the current signal generated by the first output drive circuit or the second output drive circuit is greater than or equal to a preset current value; a logic circuit, one input terminal of which is electrically connected to an output terminal of the soft-start circuit; and a voltage pull-down circuit electrically connected to the output terminal of the logic circuit; wherein when the overcurrent protection circuit detects that the current signal generated by the first output drive circuit or the second output drive circuit is greater than or equal to the preset current value within a time less than an overcurrent delay, the logic circuit generates a current sustaining signal to the first output drive circuit and the second output drive circuit based on the high-level signal to maintain the signal level of the first output signal and the signal level of the second output signal; When the overcurrent protection circuit detects that the current signal generated by the first output drive circuit or the second output drive circuit is greater than or equal to the current preset value within an overcurrent delay time greater than or equal to the overcurrent delay time, the logic circuit generates a voltage pull-down signal to the voltage pull-down circuit based on the high-level signal. This causes the voltage pull-down circuit to pull down the signal level of the first output signal and the signal level of the second output signal, making the signal level of the first output signal and the signal level of the second output signal less than the gate start voltage of the first output drive circuit and the second output drive circuit.

6. The low-power solid-state relay with protection circuitry as described in claim 1 further comprises: an over-temperature protection circuit disposed around the first output drive circuit and the second output drive circuit to sense a temperature signal generated by the first output drive circuit and the second output drive circuit; a logic circuit, one input terminal of which is electrically connected to the over-temperature protection circuit, and one output terminal of which is electrically connected to the first output drive circuit and the second output drive circuit; and a voltage pull-down circuit electrically connected to the output terminal of the logic circuit; wherein when the temperature signal is greater than or equal to a preset temperature value, the over-temperature protection circuit generates an over-temperature signal to the logic circuit, causing the logic circuit to generate a high-level signal to the voltage pull-down circuit, causing the voltage pull-down circuit to pull down the signal level of the first output signal and the signal level of the second output signal, and making the signal level of the first output signal and the signal level of the second output signal less than the gate-start voltage of the first output drive circuit and the second output drive circuit.

7. A low-power solid-state relay with a protection circuit as described in claim 6, wherein the over-temperature protection circuit comprises: a first transistor receiving a bias voltage and a control voltage; a second transistor receiving the bias voltage and the control voltage; a bias resistor connected to the second transistor; and a third transistor connected to the first transistor, the second transistor, and the bias resistor; wherein when the temperature signal is less than the preset temperature value, the bias voltage and the control voltage are less than one of the turn-on voltages of the third transistor, and the third transistor is turned off; when the temperature signal is greater than or equal to the preset temperature value, the bias voltage and the control voltage are greater than or equal to the turn-on voltage of the third transistor, and the third transistor is turned on to generate the over-temperature signal.

8. A low-power solid-state relay with protection circuitry as described in claim 5, wherein the logic circuitry comprises: a second comparator having a first input, a second input, and an output, the first input being connected to the overcurrent protection circuitry, and the second input receiving the current preset value; and a third reverse gate having an input and an output, the input of the third reverse gate being electrically connected to the output of the second comparator, and the output of the third reverse gate being electrically connected to the voltage pull-down circuitry; When the high-level signal generated by the overcurrent protection circuit is greater than or equal to the preset current value, the second comparator generates an overcurrent switching signal to the third reverse gate. The third reverse gate outputs a low-level signal to the voltage pull-down circuit, causing the voltage pull-down circuit to pull down the signal level of the first output signal and the signal level of the second output signal, and making the signal level of the first output signal and the signal level of the second output signal less than the gate start voltage of the first output drive circuit and the second output drive circuit.

9. The low-power solid-state relay with protection circuitry as described in claim 6, wherein the logic circuitry further comprises: a third comparator having a first input, a second input, and an output, the first input being connected to the over-temperature protection circuit, and the second input receiving the preset temperature value; and a fourth reverse gate having an input and an output, the input of the fourth reverse gate being connected to the output of the third comparator, and the output of the fourth reverse gate being electrically connected to the voltage pull-down circuitry; When the high-level signal generated by the over-temperature protection circuit is greater than or equal to the preset temperature value, the third comparator generates an over-temperature switching signal to the fourth reverse gate. The fourth reverse gate outputs a low-level signal to the voltage pull-down circuit, causing the voltage pull-down circuit to pull down the signal level of the first output signal and the signal level of the second output signal, and making the signal level of the first output signal and the signal level of the second output signal less than the gate start voltage of the first output drive circuit and the second output drive circuit.

10. A low-power solid-state relay with protection circuitry as described in claim 1, wherein the soft-start circuitry includes a timing circuit, a first comparator, a first reverse gate, and a second reverse gate; the timing circuitry includes a charging capacitor, receives a control voltage, and generates a capacitor voltage based on the control voltage; a first input terminal of the first comparator is electrically connected to the charging capacitor to receive the capacitor voltage; a second input terminal of the first comparator receives a buffer voltage; an output terminal of the first comparator is electrically connected to an input terminal of the first reverse gate; an output terminal of the first reverse gate is electrically connected to an input terminal of the second reverse gate and the first switch; and an output terminal of the second reverse gate is electrically connected to the second switch; wherein when the capacitor voltage is less than the buffer voltage, the first comparator and the first reverse gate generate the first control signal to the first switch; wherein when the capacitor voltage is greater than or equal to the buffer voltage, the first comparator, the first reverse gate, and the second reverse gate generate the second control signal to the second switch; and the low-power solid-state relay with protection circuitry further includes: An overcurrent protection circuit, one input terminal of which is electrically connected to the first output drive circuit and the second output drive circuit, generates an overcurrent signal when the current signal generated by the first output drive circuit or the second output drive circuit is greater than or equal to a preset current value; an overtemperature protection circuit, disposed around the first output drive circuit and the second output drive circuit, senses a temperature signal generated by the first output drive circuit and the second output drive circuit; a logic circuit having a first input terminal, a second input terminal, a third input terminal, and an output terminal, the first input terminal, the second input terminal, and the third input terminal of the logic circuit being electrically connected to the soft-start circuit, the overcurrent protection circuit, and the overtemperature protection circuit, respectively; and a voltage pull-down circuit electrically connected to the output terminal of the logic circuit. When the temperature signal is greater than or equal to a preset temperature value, the over-temperature protection circuit generates an over-temperature signal to the logic circuit, causing the logic circuit to generate a voltage pull-down signal to the voltage pull-down circuit. This causes the voltage pull-down circuit to pull down the signal level of the first output signal and the signal level of the second output signal, making the signal level of the first output signal and the signal level of the second output signal less than the gate start voltage of the first output drive circuit and the second output drive circuit.

11. A low-power solid-state relay with protection circuitry as described in claim 10, wherein the logic circuitry comprises: a second comparator having a first input, a second input, and an output, the first input being connected to the overcurrent protection circuit and receiving the overcurrent signal, and the second input receiving the current preset value; wherein when the overcurrent signal is greater than or equal to the current preset value, the second comparator outputs an overcurrent high-level signal; a state latch having an input and an output, the input being electrically connected to the output of the second comparator, generating and storing a logic signal based on the overcurrent high-level signal; and a third comparator having a first input, a second input, and an output, the first input being connected to the overtemperature protection circuit and receiving the overtemperature signal, and the second input receiving the temperature preset value; wherein when the overtemperature signal is greater than or equal to the temperature preset value, the third comparator outputs an overtemperature high-level signal. A fourth comparator has a first input terminal, a second input terminal, and an output terminal. The first input terminal of the fourth comparator is connected to the soft-start circuit. The second input terminal receives a preset voltage value and generates an overcurrent delay time based on the preset voltage value. When the second comparator outputs an overcurrent high-level signal when the overcurrent delay time is less than the preset overcurrent delay time, the fourth comparator generates an overcurrent high-level signal. When the second comparator outputs an overcurrent high-level signal when the overcurrent delay time is greater than or equal to the preset overcurrent delay time, the fourth comparator generates an overcurrent low-level signal. An inverting... The gate has a plurality of input terminals and an output terminal. The plurality of input terminals are electrically connected to the output terminal of the third comparator, the output terminal of the fourth comparator, and the output terminal of the state latch, respectively. They receive the overcurrent high level signal, the overtemperature high level signal, the overcurrent high level signal, and the overcurrent low level signal, respectively, and invert the overcurrent high level signal, the overtemperature high level signal, the overcurrent high level signal, or the overcurrent low level signal. The gate generates the voltage pull-down signal based on the inverted overcurrent high level signal, the overtemperature high level signal, or the overcurrent low level signal.

12. The low-power solid-state relay with protection circuitry as described in claim 10 further comprises: a third isolation circuit for receiving and converting a third input signal into a third output signal; and a voltage regulator circuit for receiving a bias voltage, a control voltage, and the third output signal, and transmitting the third output signal to the electrically connected soft-start circuit, the logic circuit, the overcurrent protection circuit, and the overtemperature protection circuit.

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