Gate driver with continuously-variable current
Circuits, methods, and systems are provided for setting a current level to be used by a current-mode gate driver. The current level may be used to source, sink, or both source and sink current to/from the gate terminal of a power device. The current level is based upon a current or voltage level input from an analog current-setting terminal. This input current or voltage level may take a value from a continuous range of current or voltage values.
1. A current-mode gate driver circuit, comprising:
an analog current-setting terminal configured to input an analog electrical signal from a source external to the current-mode gate driver circuit;
an adjustable current generator having an input coupled to the analog current-setting terminal and configured to generate a reference current level that follows a voltage or current level at the analog current-setting terminal;
an output terminal for coupling to a gate terminal of a power device;
an output stage configured to drive the output terminal with a current drive level that is based upon the reference current level, the output stage comprising:
a pull-up current mirror coupled in series with a pull-up switch device, wherein the pull-up switch device provides a switchable connection between the pull-up current mirror and the output terminal, and wherein the pull-up current mirror is configured to source current, to the output terminal and through the pull-up switch device, based upon the reference current level, and/or
a pull-down current mirror coupled in series with a pull-down switch device, wherein the pull-down switch device provides a switchable connection between the pull-down current mirror and the output terminal, and wherein the pull-down current mirror is configured to sink current, from the output terminal and through the pull-down switch device, based upon the reference current level; and
an input control terminal for switching the output stage.
2. The current-mode gate driver circuit of claim 1 , wherein the output stage comprises both the pull-up current mirror and the pull-down current mirror, and wherein the adjustable current generator provides, to the pull-up current mirror, a pull-up reference current that is a factor of N greater than the reference current, and provides, to the pull-down current mirror, a pull-down reference current that is a factor of M greater than the reference current.
3. The current-mode gate driver circuit of claim 2 , wherein M and N are different.
4. The current-mode gate driver of claim 2 ,
wherein the pull-up current mirror is configured such that the current sourced to the output terminal is a factor of K greater than the pull-up reference current,
wherein the pull-down current mirror is configured such that the current sunk from the output terminal is a factor of H greater than the pull-down reference current.
5. The current-mode gate driver of claim 1 , wherein the adjustable current generator comprises:
an amplifier having a non-inverting input, an inverting input and an amplifier output;
an adjustable current generator switch having a control terminal coupled to the amplifier output, a first terminal coupled to an inverting input of the amplifier, and a second terminal,
wherein a current having the reference current level flows through the adjustable current switch.
6. The current-mode gate driver of claim 5 , wherein the non-inverting input is coupled to a reference voltage, the inverting input is coupled to the analog current-setting terminal which is configured for coupling to an external programming resistor, and the reference current level is set based on the reference voltage and a resistance of the external programming resistor.
7. The current-mode gate driver of claim 5 , wherein the inverting input is coupled to a ground via a programming resistor, the non-inverting input is coupled to the analog current-setting terminal which is configured for coupling to an external reference voltage, and the reference current level is based on the external reference voltage and a resistance of the programming resistor.
8. The current-mode gate driver of claim 1 , wherein the analog current-setting terminal is configured for connection to an external current source, and the reference current level is set by a current of the external current source.
9. The current-mode gate driver of claim 1 , wherein the analog current-setting terminal is configured to input a pulse-width-modulated (PWM) signal having a first frequency, and wherein the adjustable current generator includes a frequency-to-current converter configured to convert the first frequency into a current having the reference current level.
10. The current-mode gate driver of claim 1 , wherein the analog current-setting terminal is configured to input a pulse-width-modulated (PWM) signal having a constant frequency and a first duty cycle, and wherein the adjustable current generator is configured to convert the first duty cycle into a current having the reference current level.
11. The current-mode gate driver of claim 10 , wherein the adjustable current generator includes a low-pass filter which filters the PWM signal and outputs a programming voltage or a programming current which determines the reference current level.
12. The current-mode gate driver of claim 1 , wherein the output stage comprises:
a plurality of pull-up switch devices;
an analog to digital converter (ADC) configured to output a digital value based upon the reference current level, wherein the digital value determines a number of the pull-up switch devices to activate.
13. The current-mode gate driver of claim 1 ,
wherein the adjustable current generator comprises a first switch through which the reference current flows, thereby generating a reference voltage across gate and source terminals of the first switch, and
wherein the output stage comprises a power switch configured such that a power switch voltage across gate and source terminals of the power switch determines a drive current level of the output stage, and the power switch voltage follows the reference voltage.
14. The current-mode gate driver circuit of claim 1 , wherein the reference current level generated by the adjustable current generator is based upon the voltage level at the analog current-setting terminal.
15. A current-mode gate driver system, comprising:
a controller configured to provide a gate current control parameter at a control output, the current control parameter being one or more of a control voltage, a control current, or a control resistance;
a power device comprising a gate terminal that controls conduction between a first power device terminal and a second power device terminal;
a current-mode gate driver circuit comprising:
an analog current-setting terminal coupled to the control output;
an adjustable current generator having an input coupled to the analog current-setting terminal and configured to generate a reference current level that follows a voltage or current level at the analog current-setting terminal;
an output terminal for coupling to the gate terminal of a power device;
an output stage configured to drive the output terminal with a current drive level that is based upon the reference current level; and
an input control terminal for switching the output stage.
16. A method within a current-mode gate driver circuit that comprises an analog current-setting terminal configured to input an analog electrical signal from a source external to the current-mode gate driver circuit, an adjustable current generator, an output terminal for coupling to a gate terminal of a power device, an output stage, and an input control terminal for switching the output stage, the method comprising:
inputting a voltage level at the analog current-setting terminal;
setting a reference current level that follows the input voltage level;
setting a current drive level for the output stage based upon the reference current level;
driving a current having the current drive level from the output stage to the output terminal; and
switching the output stage based upon a control signal provided at the input control terminal.
17. A current-mode gate driver circuit, comprising:
an analog current-setting terminal configured to input an analog electrical signal from a source external to the current-mode gate driver circuit;
an adjustable current generator having an input coupled to the analog current-setting terminal and configured to generate a reference current level based upon a voltage level at the analog current-setting terminal;
an output terminal for coupling to a gate terminal of a power device;
an output stage configured to drive the output terminal with a current drive level that is based upon the reference current level; and
an input control terminal for switching the output stage.