초록 ▼

A power control circuit includes sensing circuitry for sensing information about operation of a power device such as an IGBT or other power FET. The sensing circuitry receives a sense input signal from the power device through a gating device such as a diode. The power control circuit also includes

A power control circuit includes sensing circuitry for sensing information about operation of a power device such as an IGBT or other power FET. The sensing circuitry receives a sense input signal from the power device through a gating device such as a diode. The power control circuit also includes active impedance circuitry for preventing the sense input signal from including spurious information received from the gating device. For example, if the gating device is a diode across which negative spikes can be capacitively coupled, the active impedance circuitry can prevent the negative spikes from reaching the sensing circuitry when the diode is off. The active impedance circuitry can take the form of a transistor connected between a power supply and a sensing node. The active impedance device can be switched on by a comparator when the voltage across the power device exceeds a reference voltage, indicating the power device is off. Alternatively, the active impedance device can be controlled by a comparator in the sensing circuitry that provides an output that similarly indicates whether the power device is on or off. The sensing circuitry and active impedance circuitry can be implemented on an integrated circuit.

대표청구항 ▼

1. A control circuit for controlling a driving circuit for driving a power device, comprising:sensing circuitry for providing a sense result signal for controlling said driving circuit in response to a sense input signal received on a sense input, the sense input signal including information receive

1. A control circuit for controlling a driving circuit for driving a power device, comprising:sensing circuitry for providing a sense result signal for controlling said driving circuit in response to a sense input signal received on a sense input, the sense input signal including information received from the power device over a circuit path from said power device to said sensing circuitry; the sense result signal including information derived from the sense input signal about operation of the power device; andcorrection circuitry included in said circuit path from said power device to said sensing circuitry for preventing the sense input signal on said circuit path from including spurious information received from the power device, said correction circuitry comprising an active impedance element for presenting a high impedance at said sense input when said power device is on thereby allowing said spurious information to be conducted through the power device and presenting a low impedance at said sense input when said power device is off, thereby shunting said spurious information through said correction circuitry and preventing said sense input signal from including said spurious information. 2. The circuit of claim 1 in which the information from the power device includes spurious negative spikes, the correction circuitry preventing negative spikes in the sense input signal. 3. The circuit of claim 2, further comprising a gating device connected between the sensing circuitry and the power device, in which the gating device is a diode and the power device is a field effect transistor (FET); the diode being turned on when the FET is on and being turned off when the FET is off; the correction circuitry preventing negative spikes in the sense input signal except when the FET is on. 4. The circuit of claim 1 in which the sensing circuitry includes a comparator for comparing signals received at first and second inputs and for providing the sense result signal at an output, the first input receiving the sense input signal and the second input receiving a reference signal; the correction circuitry receiving the sense result signal from the comparator's output and preventing negative spikes in the sense input signal when the sense result signal indicates that the sense input signal is greater than the reference signal. 5. The circuit of claim 4, further comprising an integrated circuit that includes the sensing circuitry and the correction circuitry; the integrated circuit further including:a sensing node for connecting to the power device; anda voltage source connected to provide the reference signal to the comparator's second input, a first resistance between a supply voltage and the sensing node, a second resistance between the sensing node and the comparator's first input, and a third resistance between the comparator's first input and ground; the voltage source and the first, second, and third resistances having values such that the sense input signal drops below the reference signal if the gating device turns on; the correction circuitry including a switchable impedance parallel to the first resistance, the switchable impedance being turned on only when the sense result signal indicates that the sense input signal is greater than the reference signal. 6. The circuit of claim 1, further comprising an integrated circuit that includes the sensing circuitry and the correction circuitry; the integrated circuit further including a sensing node for connecting to the power device; the correction circuitry including a switchable impedance between a power supply and the sensing node and switching circuitry for switching the impedance on and off in response to a device state signal indicating whether the power device is on or off, the switchable impedance being turned on except when the device state signal indicates that the power device is on. 7. The circuit of claim 6 in which the correction circuitry further includes a comparator for comparing signals received at first and second inputs and for providing the device state signal at its output, the first input receiving a voltage at the sensing node and the second input receiving a reference voltage; the comparator's output being connected for turning the switchable impedance on only when the device state signal indicates that the sensing node voltage is greater than the reference voltage. 8. The circuit of claim 6 in which the sensing circuitry provides the device state signal to the switching circuitry. 9. An integrated control circuit for controlling a driving circuit for driving a power device, comprising:a sensing node for connecting to the power device;sensing circuitry for providing a sense result signal for controlling said driving circuit in response to a sense input signal received at the sensing node, the sense input signal including information received at the sensing node from the power device over a circuit path from said power device to said sensing circuitry; the sense result signal including information derived from the sense input signal about operation of the power device; andcorrection circuitry included in said circuit path from said power device to said sensing circuitry for preventing the sense input signal on said circuit path from including spurious information received at the sensing node from the power device, said correction circuitry comprising an active impedance element for presenting a high impedance at said sensing node when said power device is on thereby allowing said spurious information to be conducted through the power device and presenting a low impedance at said sensing node when said power device is off, thereby shunting said spurious information through said correction circuitry and preventing said sense input signal from including said spurious information. 10. The circuit of claim 9 in which the sensing node is a desat/voltage feedback pin and in which the information from the power device includes spurious negative spikes to the sensing node, the correction circuitry being connected to the sensing node to prevent negative spikes in the sense input signal. 11. The circuit of claim 10, further comprising a gating device connected between the sensing circuitry and the power device, in which the gating device is a diode and the power device is a field effect transistor (FET); the diode being turned on when the FET is on and being turned off when the FET is off; the correction circuitry preventing negative spikes in the sense input signal except when the FET is on. 12. The circuit of claim 9 in which the sensing circuitry includes a comparator for comparing signals received at first and second inputs and for providing the sense result signal at an output, the first input receiving the sense input signal and the second input receiving a reference signal; the correction circuitry receiving the sense result signal from the comparator's output and preventing negative spikes in the sense input signal only when the sense result signal indicates that the sense input signal is greater than the reference signal. 13. The circuit of claim 12, further comprising a voltage source connected to provide the reference signal to the comparator's second input, a first resistance between a supply voltage and the sensing node, a second resistance between the sensing node and the comparator's first input, and a third resistance between the comparator's first input and ground; the capacitance and the first, second, and third resistances having values such that the sense input signal drops below the reference signal if the gating device turns on; the correction circuitry including a switchable impedance path parallel to the first resistance, the switchable impedance path being turned on only when the sense result signal indicates that the sense input signal is greater than the reference signal. 14. The circuit of claim 9 in which the correction circuitry includes a switchable impedance betwee n a power supply and the sensing node and switching circuitry for switching the impedance on and off in response to a device state signal indicating whether the power device is on or off, the switchable impedance being turned on except when the device state signal indicates that the power device is on. 15. The circuit of claim 14 in which the correction circuitry further includes a comparator for comparing signals received at first and second inputs and for providing the device state signal at its output, the first input receiving a voltage at the sensing node and the second input receiving a reference voltage; the comparison result signal being connected for turning the switchable impedance on only when the device state signal indicates that the sensing node voltage is greater than the reference voltage. 16. The circuit of claim 14 in which the sensing circuitry provides the device state signal to the switching circuitry. 17. An integrated control circuit for controlling respective high side and low side driving circuits for driving high and low side power devices connected in a half bridge, the control circuit comprising high side circuitry for controlling the high side driving circuit and low side circuitry for controlling the low side driving circuit;the high side circuitry comprising:a first sensing node for connecting to the high side power device;first sensing circuitry for providing a first sense result signal for controlling said high side driving circuit in response to a first sense input signal received at said first sensing node, the first sense input signal including information received at the first sensing node from the high side power device over a first circuit path from said high side power device to said first sensing circuitry; the first sense result signal including information derived from the first sense input signal about operation of the high side power device; andfirst correction circuitry included in said first circuit path from said high side power device to said first sensing circuitry for preventing the first sense input signal on said first circuit path from including spurious information received at the first sensing node, said first correction circuitry comprising an active impedance element for presenting a high impedance at said first sensing node when said power device is on thereby allowing said spurious information to be conducted through the power device and presenting a low impedance at said first sensing node when said power device is off, thereby shunting said spurious information through said first correction circuitry and preventing said sense input signal from including said spurious information; andthe low side circuitry comprising:a second sensing node for connecting to the low side power device;second sensing circuitry for providing a second sense result signal for controlling said low side driving circuit in response to a second sense input signal received at the second sensing node, the second sense input signal including information received at the second sensing node from the low side power device over a second circuit path from said low side power device to said second sensing circuitry; the second sense result signal including information derived from the second sense input signal about operation of the low side power device; andsecond correction circuitry included in said second circuit path from said low side power device to said second sensing circuitry for preventing the second sense input signal on said second circuit path from including spurious received at the second sensing node, said second correction circuitry comprising an active impedance element for presenting a high impedance at said when said power device is on thereby allowing said spurious information to be conducted through the power device and presenting a low impedance at said second sensing node when said power device is off, thereby shunting said spurious information through said second correction circ uitry and preventing said second sense input signal from including said spurious information. 18. The circuit of claim 1, further comprising a driving circuit, wherein said driving circuit receives an input voltage and generates a driving signal for said power device. 19. The circuit of claim 9, further comprising a driving circuit in said integrated circuit, wherein said driving circuit receives an input voltage and generates a driving signal for said power device. 20. An integrated control circuit for controlling respective high side and low side driving circuits for driving high and low side power devices connected in a half bridge, the integrated control circuit comprising high side circuitry for controlling the high side driving circuit and low side circuitry for controlling the low side driving circuit;the high side circuitry comprising:a first sensing node for connecting to the high side power device;first sensing circuitry for providing a first sense result signal for controlling said high side driving circuit in response to a first sense input signal received at the first sensing node, the first sense input signal including information received at the first sensing node from the high side power device over a first circuit path from said high side power device to said first sensing circuitry; the first sense result signal including information derived from the first sense input signal about operation of the high side power device; andfirst correction circuitry included in said first circuit path from said high side power device to said first sensing circuitry for preventing the first sense input signal on said first circuit path from including spurious information received at the first sensing node, said first correction circuitry comprising an active impedance element for presenting a high impedance at said first sensing node when said power device is on thereby allowing said spurious information to be conducted through the power device and presenting a low impedance at said first sensing node when said power device is off, thereby shunting said spurious information through said first correction circuitry and preventing said sense input signal from including said spurious information; andthe low side circuitry comprising:a second sensing node for connecting to the low side power device;second sensing circuitry for providing a second sense result signal for controlling said low side driving circuit in response to a second sense input signal received at the second sensing node, the second sense input signal including information received at the second sensing node from the low side power device over a second circuit path from said low side power device to said second sensing circuitry; the second sense result signal including information derived from the second sense input signal about operation of the low side power device;second correction circuitry included in said second circuit path from said low side power device to said second sensing circuitry for preventing the second sense input signal on said second circuit path from including spurious information received at the second sensing node, said second correction circuitry comprising an active impedance element for presenting a high impedance at said second sensing node when said power device is on thereby allowing said spurious information to be conducted through the power device and presenting a low impedance at the second sensing node when said power device is off, thereby shunting said spurious information through said second correction circuitry and preventing said second sense input signal from including said spurious information;said integrated circuit further comprising said high side driving circuit disposed in said integrated circuit, wherein said high side driving circuit receives an input voltage and generates a driving signal for said high side power device; andsaid integrated circuit further comprising said low side driving circuit disposed in said int egrated circuit, wherein said low side driving circuit receives an input voltage and generates a driving signal for said low side power device. 21. The circuit of claim 9, in which the gating device provides spurious negative spikes, the correction circuitry preventing negative spikes in the sense input signal. 22. The circuit of claim 17, in which the gating device provides spurious negative spikes, the correction circuitry preventing negative spikes in the sense input signal. 23. The circuit of claim 1, wherein said spurious information includes at least one of high-frequency noise and a negative voltage spike. 24. The circuit of claim 9, wherein said spurious information includes at least one of high-frequency noise and a negative voltage spike. 25. The circuit of claim 17, wherein said spurious information includes at least one of high-frequency noise and a negative voltage spike. 26. The circuit of claim 5, further comprising a driving circuit in said integrated circuit, wherein said driving circuit receives an input voltage and generates a driving signal for said power device. 27. The circuit of claim 6, further comprising a driving circuit in said integrated circuit, wherein said driving circuit receives an input voltage and generates a driving signal for said power device.