Sensing device for high voltage applications
In a general aspect, an integrated circuit (IC) can include a low-voltage region including a low-side driver circuit configured to control a low-side switch of a power converter. The IC can also include a high-voltage region including a floating region of a first conductivity and a high-voltage sensing device disposed in the floating region. The high-voltage sensing device can include a junction-field effect transistor (JFET), and a voltage divider. The voltage divider can include a first terminal coupled to a drain of the JFET, a second terminal coupled to a gate of the JFET, and a sense terminal, the voltage divider being configured to a provide, on the sense terminal. The IC can further include a high-side driver circuit coupled with the sense terminal. The high-side driver circuit can be configured to control a high-side switch of the power converter based on the voltage on the sense terminal.
1. An integrated circuit, comprising:
a semiconductor substrate;
a low-voltage region included in the semiconductor substrate, the low-voltage region including:
a low-side driver circuit configured to control a low-side switch of a power converter;
a high-voltage region included in the semiconductor substrate, the high-voltage region including:
a floating region of a first conductivity type;
a high-voltage sensing device disposed in the floating region, the high-voltage sensing device including:
a junction-field effect transistor (JFET), the JFET being configured to operate in pinch-off mode; and
a voltage divider including:
a first terminal coupled to a drain of the JFET;
a second terminal coupled to a gate of the JFET; and
a sense terminal, the voltage divider being configured to provide, on the sense terminal, a voltage indicative of a voltage differential between the drain of the JFET and the gate of the JFET; and
a high-side driver circuit coupled with the sense terminal, the high-side driver circuit being configured to control a high-side switch of the power converter based on the voltage on the sense terminal.
2. The integrated circuit of claim 1 , wherein:
a source of the JFET is configured to be coupled with a bootstrap voltage of the power converter, the bootstrap voltage varying, based on a voltage of a switch node of the power converter, between a first voltage and a second voltage; and
the gate of the JFET is coupled with the switch node of the power converter,
the first voltage being a power supply voltage of the integrated circuit, and
the second voltage being a high-voltage power supply voltage of the power converter plus the power supply voltage of the integrated circuit.
3. The integrated circuit of claim 1 , wherein the JFET further includes:
a source of a second conductivity type, the second conductivity type being opposite the first conductivity type,
the drain of the JFET being of the second conductivity type; and
the gate of the JFET being of the first conductivity type.
4. The integrated circuit of claim 3 , wherein:
the first conductivity type is p-type; and
the second conductivity type is n-type.
5. The integrated circuit of claim 1 , wherein the voltage differential is a voltage differential between a high-voltage power supply and a switch node of the power converter.
6. The integrated circuit of claim 1 , wherein the voltage differential is a voltage differential across a high-side current sense resistor of the power converter.
7. The integrated circuit of claim 1 , wherein the voltage divider includes a resistive-capacitive voltage divider coupled between the drain of the JFET and the gate of the JFET.
8. The integrated circuit of claim 7 , wherein the resistive-capacitive voltage divider includes:
a first capacitor coupled between the drain of the JFET and the sense terminal; and
a second capacitor coupled between the sense terminal and the gate of the JFET.
9. The integrated circuit of claim 8 , wherein:
the first capacitor includes a capacitive network disposed within the floating region; and
the second capacitor includes a metal-oxide metal capacitor.
10. The integrated circuit of claim 8 , wherein the second capacitor is disposed in the low-voltage region.
11. The integrated circuit of claim 7 , wherein the resistive-capacitive voltage divider includes:
a spiral resistive element disposed in the floating region, the sense terminal being coupled to the spiral resistive element to define a first resistor and a second resistor of the resistive-capacitive voltage divider,
the first resistor being coupled between the drain of the JFET and the sense terminal; and
the second resistor being coupled between the sense terminal and the gate of the JFET.
12. The integrated circuit of claim 11 , wherein a ratio of a resistance of the first resistor to a resistance of the second resistor is greater than 100 to 1.
13. The integrated circuit of claim 1 , wherein the voltage divider includes at least one of:
a resistive voltage divider; or
a capacitive voltage divider.
14. The integrated circuit of claim 1 , wherein the low-side driver circuit and the high-side driver circuit are included in a pulse-width modulation controller.
15. The integrated circuit of claim 1 , further comprising a high-voltage junction termination region disposed between the low-voltage region and the high-voltage region.
16. The integrated circuit of claim 15 , wherein the high-voltage junction termination region surrounds the floating region.
17. The integrated circuit of claim 15 , wherein the JFET is a first JFET, the high-voltage junction termination region including a second JFET,
the first JFET being a first n-channel JFET and the second JFET being a second n-channel JFET,
a gate of the second n-channel JFET being coupled to electrical ground,
a source of the second n-channel JFET being configured to be electrically floating.
18. An integrated circuit, comprising:
a semiconductor substrate;
a low-voltage region included in the semiconductor substrate, the low-voltage region including:
a low-side driver circuit configured to control a low-side switch of a power converter;
a high-voltage region included in the semiconductor substrate, the high-voltage region including:
a floating region of a first conductivity type;
a high-voltage sensing device disposed in the floating region, the high-voltage sensing device including:
a first junction-field effect transistor (JFET), the first JFET being configured to operate in pinch-off mode; and
a voltage divider including:
a first terminal coupled to a drain of the first JFET;
a second terminal coupled to a gate of the first JFET; and
a sense terminal, the voltage divider being configured to provide, on the sense terminal, a voltage indicative of a voltage differential between the drain of the first JFET and the gate of the first JFET;
a high-side driver circuit coupled with the sense terminal, the high-side driver circuit being configured to control a high-side switch of the power converter based on the voltage on the sense terminal; and
a high-voltage junction termination region surrounding the floating region, the high-voltage junction termination region including a second JFET.
19. The integrated circuit of claim 18 , wherein:
the first JFET is a first n-channel JFET and the second JFET is a second n-channel JFET,
a gate of the second n-channel JFET is coupled to electrical ground,
a source of the first n-channel JFET and a source of the second n-channel JFET are configured to be coupled with a bootstrap voltage of the power converter, the bootstrap voltage varying, based on a voltage of a switch node of the power converter, between a first voltage and a second voltage,
the first voltage being a power supply voltage of the integrated circuit, and
the second voltage being a high-voltage power supply voltage of the power converter plus the power supply voltage of the integrated circuit.
20. An integrated circuit, comprising:
a semiconductor substrate;
a low-voltage region included in the semiconductor substrate, the low-voltage region including:
a low-side driver circuit configured to control a low-side switch of a power converter;
a high-voltage region included in the semiconductor substrate, the high-voltage region including:
a floating region of a first conductivity type;
a high-voltage sensing device disposed in the floating region, the high-voltage sensing device including:
a junction-field effect transistor (JFET), the JFET being configured to operate in pinch-off mode; and
a resistive-capacitive voltage divider including:
a first terminal coupled to a drain of the JFET;
a second terminal coupled to a gate of the JFET; and
a sense terminal, the resistive-capacitive voltage divider being configured to provide, on the sense terminal, a voltage indicative of a voltage differential between the drain of the JFET and the gate of the JFET,
the resistive-capacitive voltage divider including:
a first capacitor coupled between the drain of the JFET and the sense terminal;
a second capacitor coupled between the sense terminal and the gate of the JFET;
a spiral resistive element, the sense terminal being coupled to the spiral resistive element to define a first resistor and a second resistor of the resistive-capacitive voltage divider, the first resistor being coupled between the drain of the JFET and the sense terminal, and the second resistor being coupled between the sense terminal and the gate of the JFET; and
a high-side driver circuit coupled with the sense terminal, the high-side driver circuit being configured to control a high-side switch of the power converter based on the voltage on the sense terminal.
21. The integrated circuit of claim 20 , wherein:
the first capacitor and the spiral resistive element are disposed in the high-voltage region; and
the second capacitor is disposed in the low-voltage region.