Power transistor, a driver, and an overvoltage protection circuit
An electronic circuit is disclosed. The circuit includes a power transistor having a gate terminal, a source terminal and a drain terminal. The electronic circuit also has a driver to generate which selectively changes a voltage at the gate terminal. The driver circuit includes a pull-down switch configured to change the voltage on the gate terminal such that the resistance between the source terminal and the drain terminal increases. The electronic circuit also has an overvoltage protection circuit coupled to the gate terminal. The overvoltage protection circuit includes a selectively conductive device configured to become conductive while reverse biased in response to an overvoltage potential. While conductive, the selectively conductive device causes the resistance between the source terminal and the drain terminal to decrease. The overvoltage protection circuit is also causes the pull-down switch to be non-conductive by applying a signal to the pull-down switch.
1. An electronic circuit comprising:
a power transistor having a gate terminal, a source terminal and a drain terminal;
a driver circuit, configured to generate an output which selectively changes a voltage at the gate terminal such that a resistance between the source terminal and the drain terminal changes in response to an input signal, and which selectively presents a high impedance to the gate terminal, wherein the driver circuit comprises a turn-off circuit configured to change the voltage on the gate terminal such that the resistance between the source terminal and the drain terminal increases, and wherein the driver circuit comprises a turn-on circuit configured to change the voltage on the gate terminal such that the resistance between the source terminal and the drain terminal decreases;
an overvoltage protection circuit coupled to the gate terminal of the power transistor, wherein the overvoltage protection circuit is configured to generate one or more overvoltage indication signals in response to an overvoltage potential, wherein, in response to the overvoltage indication signals, the overvoltage protection circuit causes a voltage at the gate terminal to change such that the resistance between the source terminal and the drain terminal decreases, and wherein, in response to the overvoltage indication signals, the driver circuit causes the turn-off circuit to present a substantially open circuit load to the gate terminal;
an amplifier configured to, in response to at least one of the overvoltage indication signals, cause the resistance of the power transistor between the source terminal and the drain terminal to decrease; and
a comparator configured to, in response to at least one of the overvoltage indication signals, cause the gate terminal to be electrically connected to an output of the amplifier.
2. The electronic circuit of claim 1 , wherein the comparator is further configured to, in response to at least one of the overvoltage indication signals, cause the turn-off circuit to present the substantially open circuit load to the gate terminal.
3. The electronic circuit of claim 2 , wherein the comparator is configured to cause the turn-off circuit to present the substantially open circuit load to the gate terminal before the amplifier causes the resistance between the source terminal and the drain terminal to decrease.
4. The electronic circuit of claim 2 , wherein the comparator is further configured to, in response to at least one of the overvoltage indication signals, cause the turn-on circuit to present the substantially open circuit load to the gate terminal.
5. The electronic circuit of claim 4 , wherein the comparator is configured to cause the turn-on circuit to present the substantially open circuit load to the gate terminal before the amplifier causes the resistance between the source terminal and the drain terminal to decrease.
6. The electronic circuit of claim 4 , wherein the comparator is configured to cause the turn-off circuit to present the substantially open circuit load to the gate terminal before the amplifier causes the resistance between the source terminal and the drain terminal to decrease.
7. The electronic circuit of claim 6 , wherein the comparator is configured to cause the turn-on circuit to present the substantially open circuit load to the gate terminal before the amplifier causes the resistance between the source terminal and the drain terminal to decrease.
8. The electronic circuit of claim 1 , wherein in response to the resistance between the source terminal and the drain terminal decreasing, a voltage difference between the drain terminal and the source terminal decreases, and wherein, after the voltage difference between the drain terminal and the source terminal has decreased, a drain terminal to source terminal path of the power transistor remains conductive.
9. The electronic circuit of claim 1 , wherein the power transistor is disposed on a first die and at least a portion of the overvoltage protection circuit is disposed on a second die that is co-packaged with the first die.
10. The electronic circuit of claim 1 , wherein the power transistor and at least one element of the overvoltage protection circuit are integrated on a single GaN-based die.
11. The electronic circuit of claim 1 , wherein the power transistor and the turn-off circuit are integrated on a single GaN-based die.
12. An electronic circuit comprising:
a power transistor having a gate terminal, a source terminal and a drain terminal;
a driver circuit, configured to generate an output which selectively changes a voltage at the gate terminal such that a resistance between the source terminal and the drain terminal changes in response to an input signal, and which selectively presents a high impedance to the gate terminal, wherein the driver circuit comprises a turn-off circuit configured to change the voltage on the gate terminal such that the resistance between the source terminal and the drain terminal increases, and wherein the driver circuit comprises a turn-on circuit configured to change the voltage on the gate terminal such that the resistance between the source terminal and the drain terminal decreases;
an overvoltage protection circuit coupled to the gate terminal of the power transistor, wherein the overvoltage protection circuit is configured to generate one or more overvoltage indication signals in response to an overvoltage potential, wherein, in response to the overvoltage indication signals, the overvoltage protection circuit causes a voltage at the gate terminal to change such that the resistance between the source terminal and the drain terminal decreases, and wherein, in response to the overvoltage indication signals, the driver circuit causes the turn-off circuit to present a substantially open circuit load to the gate terminal;
an amplifier configured to, in response to at least one of the overvoltage indication signals, cause the resistance of the power transistor between the source terminal and the drain terminal to decrease; and
a comparator configured to, in response to at least one of the overvoltage indication signals, cause the turn-off circuit to present the substantially open circuit load to the gate terminal.
13. The electronic circuit of claim 12 , wherein in response to the resistance between the source terminal and the drain terminal decreasing, a voltage difference between the drain terminal and the source terminal decreases, and wherein, after the voltage difference between the drain terminal and the source terminal has decreased, a drain terminal to source terminal path of the power transistor remains conductive.
14. The electronic circuit of claim 12 , wherein the power transistor is disposed on a first die and at least a portion of the overvoltage protection circuit is disposed on a second die that is co-packaged with the first die.
15. The electronic circuit of claim 12 , wherein the power transistor and at least one element of the overvoltage protection circuit are integrated on a single GaN-based die.
16. The electronic circuit of claim 12 , wherein the power transistor and the turn-off circuit are integrated on a single GaN-based die.
17. A method of protecting a power transistor from an overvoltage transient condition, the method comprising:
holding a power transistor in an off state by connecting a gate of the power transistor to a source of the power transistor through a pull-down switch;
turning on a drive switch during an overvoltage transient condition by providing a current into a gate of the drive switch through a zener diode coupled between the gate and a drain of the power transistor, the zener diode further coupled to the gate of the drive switch;
shorting a gate of the pull-down switch to a source of the pull-down switch by a turn-on of the drive switch;
providing a current through the zener diode into the gate of the power transistor, thereby raising a voltage at the gate of the power transistor and turning on the power transistor during the overvoltage transient condition; and
discharging an overvoltage transient current through the drain to the source of the power transistor.
18. The method of claim 17 , wherein the power transistor and the pull-down switch are integrated on a single GaN-based die.
19. The method of claim 17 , wherein the power transistor and the pull-down switch and the drive switch are integrated on a single GaN-based die.