# US 11,101,791 B2 · Power circuit switching device having a passive protection circuit > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,101,791 B2 - Document ID: US11101791B2 - Status: Granted - Kind: B2 - Application number: 16/464,184 - Filed: 2017-11-22 - Published: 2020-09-17 - Granted: 2021-08-24 - Earliest claimed: 2016-11-25 - Assignees: Exagan - Applicants: Exagan - Inventors: Laurent Guillot; Thierry Sutto; Eric Moreau - Web page: https://patentgrep.com/patent/US11101791B2 ## CPC - H03K 17/08: Modifications for protecting switching circuit against overcurrent or overvoltage - H03K 17/102: {in field-effect transistor switches} - H03K 17/162: {without feedback from the output circuit to the control circuit} - H03K 17/223: {in field-effect transistor switches} - H03K 17/687: the devices being field-effect transistors - H03K 2017/6875: {using self-conductive, depletion FETs} - H03K 2217/0081: Power supply means, e.g. to the switch driver - H03K: PULSE TECHNIQUE (measuring pulse characteristics G01R; modulating sinusoidal oscillations with pulses H03C; transmission of digital information H04L; discriminator circuits detecting phase difference between two signals by counting or integrating cycles of oscillation H03D3/04; automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or pulses where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M) ## Abstract A power circuit switching device comprises two switching terminals, a high-voltage depletion mode transistor and a low-voltage enhancement mode transistor arranged in series between the two switching terminals, a first terminal for receiving a switching signal and electrically connected via a driver circuit to the gate of the high-voltage transistor, and a second terminal for receiving a control signal and electrically connected to the gate of the low-voltage transistor. The device comprises a normally-on protection circuit electrically connected between the second terminal and the gate of the high-voltage transistor to keep the high-voltage transistor in an off-state when the driver circuit is not electrically powered. ## Claims ### Claim 1 A power circuit switching device comprising: two switching terminals; a high-voltage depletion mode transistor and a low-voltage enhancement mode transistor arranged in series between the two switching terminals, the avalanche voltage of the low-voltage transistor being lower than the avalanche voltage of the high-voltage transistor; a first terminal for receiving a switching signal, electrically connected via a driver circuit to a gate of the high-voltage transistor; a second terminal for receiving a control signal, electrically connected to the gate of the low-voltage transistor; a normally-on protection circuit electrically connected between the second terminal and the gate of the high-voltage transistor to keep the high-voltage transistor in an off-state when the driver circuit is not electrically powered; and a control device electrically connected to the first terminal and the second terminal for processing the control signal and selectively transmitting the switching signal. ### Claim 2 (depends on 1) The switching device according to claim 1, wherein the protection circuit comprises a bipolar transistor and a resistor placed in an emitter of the bipolar transistor. ### Claim 3 (depends on 2) The switching device according to claim 2, wherein the base of the bipolar transistor is electrically connected to the second terminal, a collector of the bipolar transistor is electrically connected to the ground of the device and the resistor is electrically connected to the gate of the high-voltage transistor. ### Claim 4 (depends on 3) The switching device according to claim 3, wherein the protection circuit includes a second resistor between the second terminal and the ground of the device. ### Claim 5 (depends on 4) The switching device according to claim 4, wherein a source of the high-voltage transistor is electrically connected to the drain of the low-voltage transistor. ### Claim 6 (depends on 5) The switching device according to claim 5, wherein the high-voltage transistor is a GaN- or SiC-based HEMT transistor. ### Claim 7 (depends on 6) The switching device according to claim 6, wherein the low-voltage transistor is a silicon-based MOSFET transistor. ### Claim 8 (depends on 7) The switching device according to claim 7, wherein the avalanche voltage of the high-voltage transistor is greater than 600V. ### Claim 9 (depends on 8) The switching device according to claim 8, further comprising a control device electrically connected to the first terminal and the second terminal for processing the control signal and selectively transmitting the switching signal. ### Claim 10 (depends on 9) The switching device according to claim 9, wherein the driver circuit is electrically powered by at least one supply voltage source (VDR+, VDR−). ### Claim 11 (depends on 10) The switching device according to claim 10, wherein the control device is electrically connected to the at least one supply voltage source for selectively switching it on or off. ### Claim 12 (depends on 2) The switching device according to claim 2, wherein the protection circuit includes a second resistor between the second terminal and the ground of the device. ### Claim 13 (depends on 1) The switching device according to claim 1, wherein a source of the high-voltage transistor is electrically connected to the drain of the low-voltage transistor. ### Claim 14 (depends on 1) The switching device according to claim 1, wherein the high-voltage transistor is a GaN- or SiC-based HEMT transistor. ### Claim 15 (depends on 1) The switching device according to claim 1, wherein the low-voltage transistor is a silicon-based MOSFET transistor. ### Claim 16 (depends on 1) The switching device according to claim 1, wherein the avalanche voltage of the high-voltage transistor is greater than 600V. ### Claim 17 (depends on 1) The switching device according to claim 1, wherein the driver circuit is electrically powered by at least one supply voltage source (VDR+, VDR−). ### Claim 18 (depends on 17) The switching device according to claim 17, wherein the control device is electrically connected to the at least one supply voltage source for selectively switching it on or off. ### Claim 19 A power circuit switching device comprising: two switching terminals; a high-voltage depletion mode transistor and a low-voltage enhancement mode transistor arranged in series between the two switching terminals, an avalanche voltage of the low-voltage transistor being lower than the avalanche voltage of the high-voltage transistor; a first terminal for receiving a switching signal, electrically connected via a driver circuit to a gate of the high-voltage transistor; a second terminal for receiving a control signal, electrically connected to the gate of the low-voltage transistor; and a normally-on protection circuit electrically connected between the second terminal and the gate of the high-voltage transistor to keep the high-voltage transistor in an off-state when the driver circuit is not electrically powered, the normally-on protection circuit comprising a bipolar transistor and a resistor placed in an emitter of the bipolar transistor.