Combined isolator and power switch
View Patent ↗A combined isolator and power switch is disclosed. Such devices are useful in isolating low voltage components such as control compilers from motors or generators working at high voltages. The combined isolator and power switch includes circuits to transfer internal power from its low voltage side to the switch driver circuits on the high voltage side. The combined isolator and switch is compact and easy to use.
1. A combined isolator and power switch, comprising:
a semiconductor power switch comprising a bipolar transistor in series combination with a field effect transistor;
an isolator operatively connected to the semiconductor power switch and arranged to control the semiconductor power switch based on a switch control signal; and
an integrated circuit package encapsulating the semiconductor power switch and the isolator and comprising a first terminal coupled to the isolator and configured to receive a supply voltage, a second terminal coupled to the isolator and configured to receive the switch control signal, a third terminal coupled to the semiconductor power switch, and a fourth terminal coupled to the semiconductor power switch.
2. The combined isolator and power switch as claimed in claim 1 , wherein a first region of semiconductor is shared by the bipolar transistor and the field effect transistor.
3. The combined isolator and power switch as claimed in claim 1 , wherein the isolator and the semiconductor power switch are packaged as a device having five active terminals.
4. The combined isolator and power switch as claimed in claim 1 , wherein the isolator comprises a micro-transformer configured to transmit data between first and second voltage domains.
5. The combined isolator and power switch as claimed in claim 4 , wherein the micro-transformer is configured to provide the data pulses representing edge transitions of an input signal.
6. The combined isolator and power switch as claimed in claim 1 , wherein the isolator is a first isolator, and wherein the combined isolator and power switch further comprises a second isolator arranged as a micro transformer coupled to a direct current (DC) to alternating current (AC) converter and an AC to DC converter arranged to deliver power from a first voltage domain to a receiver and switch driver in a second voltage domain, wherein the first isolator is configured to transfer the switch control signal from the first voltage domain to the second voltage domain.
7. The combined isolator and power switch as claimed in claim 1 , wherein the semiconductor power switch is formed vertically within a semiconductor substrate.
8. The combined isolator and power switch as claimed in claim 1 , wherein the semiconductor power switch comprises a drive field effect transistor having a gate formed within a vertically extending channel.
9. The combined isolator and power switch as claimed in claim 1 , wherein the field effect transistor is a junction field effect transistor that has a channel formed between insulated gate electrodes, and wherein a pinch off voltage of the field effect transistor is based on a distance between the insulated gate electrodes.
10. The combined isolator and power switch as claimed in claim 1 , wherein the field effect transistor is formed between regions of an opposing type of semiconductor material to that of a collector region of the bipolar transistor.
11. The combined isolator and power switch as claimed in claim 1 , wherein the isolator is a first isolator, wherein the combined isolator and power switch further comprises a power transfer circuit that comprises a second isolator, wherein the power transfer circuit is configured to transfer power from a first voltage domain to a second voltage domain, and wherein the first isolator is configured to transfer the switch control signal from the first voltage domain to the second voltage domain.
12. The combined isolator and power switch as claimed in claim 1 , wherein the bipolar transistor and the field effect transistor are arranged such that the field effect transistor serves to limit a voltage across an active region of the bipolar transistor with gains in excess of 10 while still providing a breakdown voltage in excess of 800 Volts.
13. A combined isolator and power switch comprising:
a first isolator configured to transmit data from a first voltage domain to a second voltage domain;
a semiconductor power switch operatively coupled to the first isolator and configured to receive a control signal in the second voltage domain;
a power transfer circuit comprising a second isolator, the power transfer circuit configured to transfer power from the first voltage domain to the second voltage domain and provide power to at least part of the first isolator in the second voltage domain; and
a package encapsulating the semiconductor power switch, the first isolator, and the second isolator.
14. The combined isolator and power switch as claimed in claim 13 , further comprising a receiver and switch driver coupled between the first isolator and the semiconductor power switch, wherein the semiconductor power switch is configured to receive the control signal by way of the receiver and switch driver, and wherein the power transfer circuit is configured to provide direct current power to the receiver and switch driver.
15. The combined isolator and power switch as claimed in claim 13 , wherein the second isolator comprises a transformer, and wherein the transformer comprises a coil formed by a conductor disposed on or within a semiconductor substrate.
16. The combined isolator and power switch as claimed in claim 13 , wherein the second isolator is coupled to a direct current (DC) to alternating current (AC) converter in the first voltage domain and coupled to an AC to DC converter in the second voltage domain.
17. The combined isolator and power switch as claimed in claim 13 , wherein the power switch comprises a junction field effect transistor in series with a bipolar transistor.
18. The combined isolator and power switch as claimed in claim 17 , wherein the power switch further comprises a drive field effect transistor coupled to the bipolar transistor, the drive field effect transistor comprising an insulated gate.
19. A combined isolator and switch comprising:
a power switch packaged within an integrated circuit package, the power switch comprising a bipolar transistor in series with a junction field effect transistor, the junction field effect transistor comprising a gate conductor disposed between insulating walls and a buried region of doped semiconductor that is in contact with the gate conductor; and
an isolator packaged within the integrated circuit package and configured to provide a control signal to the power switch.
20. The combined isolator and power switch as claimed in claim 19 , wherein the power switch and at least a portion of the isolator are on a common semiconductor die.
21. A combined isolator and switch, comprising:
a semiconductor power switch comprising a bipolar transistor in series with a junction field effect transistor, the junction field effect transistor comprising a gate conductor disposed between insulating walls and a buried region of doped semiconductor that is in contact with the gate conductor;
an isolator operatively connected to the semiconductor power switch and configured to provide a control signal to the semiconductor power switch; and
an integrated circuit package encapsulating the semiconductor power switch and the isolator.