Gate drive controller circuit with anti-saturation circuit and power up circuit therefor
View Patent ↗A high side isolated gate drive controller circuit is presented with an on-time limiting circuit to prevent isolation transformer saturation as well as a universal power up circuit adaptable to power the driver with constant voltage for different input voltage levels.
1. A driver circuit for driving a control terminal of a transistor, the driver circuit comprising:
a first driver output operative to selectively provide a drive signal to a control terminal of a transistor;
a second driver output coupleable to a second terminal of the transistor;
a driver transformer comprising:
a core,
a primary winding wound on the core, and
a secondary winding wound on the core having a first end and a second end coupled with the second driver output;
a pulse width modulation (PWM) controller comprising:
a PWM output, and
a control input;
a first capacitor coupled between a first end of the primary winding of the driver transformer and the PWM output;
a second capacitor coupled between the first end of the secondary winding of the driver transformer and the first driver output;
a first rectifier coupled between the first driver output and the second driver output; and
a limiting circuit, comprising:
a limiting circuit input coupled with the PWM output, and
a limiting control output coupled with the PWM controller, the limiting control output providing a limiting control signal to the control input to limit an on-time of the PWM output to be at or below an on-time threshold value.
2. The driver circuit of claim 1 , where the on-time threshold value is set to avoid saturation of the core of the driver transformer.
3. The driver circuit of claim 2 , where the limiting circuit comprises:
a resistor coupled between the limiting circuit input and an intermediate node;
a limiting circuit capacitance coupled between the intermediate node and a circuit ground; and
a limiting circuit diode comprising an anode coupled with the intermediate node and a cathode coupled with the limiting control output.
4. The driver circuit of claim 3 :
where the limiting circuit has a time constant set by the second resistor and the limiting circuit capacitance;
where the time constant determines a rise time of a voltage of the intermediate node of the limiting circuit to rise to a threshold voltage value when the PWM output of the PWM controller is activated; and
where the rise time of the voltage of the intermediate node of the limiting circuit determines the on-time threshold value.
5. The driver circuit of claim 1 , where the limiting circuit comprises:
a resistor coupled between the limiting circuit input and an intermediate node;
a limiting circuit capacitance coupled between the intermediate node and a circuit ground; and
a limiting circuit diode comprising an anode coupled with the intermediate node and a cathode coupled with the limiting control output.
6. The driver circuit of claim 5 :
where the limiting circuit has a time constant set by the resistor and the limiting circuit capacitance;
where the time constant determines a rise time of a voltage of the intermediate node of the limiting circuit to rise to a threshold voltage value when the PWM output of the PWM controller is activated; and
where the rise time of the voltage of the intermediate node of the limiting circuit determines the on-time threshold value.
7. The driver circuit of claim 6 , further comprising a power up circuit providing power to the PWM controller, the power up circuit comprising:
an input coupleable to an AC input source;
a power up circuit transformer, comprising:
a power up transformer primary winding coupled to the input to receive AC input power from the AC input source,
a first power up transformer secondary winding with a first end coupled to a first power up circuit rectifier and a second end coupled to a circuit ground, and
a second power up transformer secondary winding with a first end coupled with the circuit ground and a second end coupled to a second power up circuit rectifier; and
an output coupled with the first and second power up circuit rectifiers and providing a generally constant output voltage to a power input of the PWM controller independent of a voltage of the AC input power.
8. The driver circuit of claim 7 :
where the first power up circuit rectifier comprises an anode coupled to the first end of the first power up transformer secondary winding and a cathode;
where the second power up circuit rectifier comprises an anode coupled to the second end of the second power up transformer secondary winding and a cathode coupled to the output; and
where the power up circuit further comprises:
a power up circuit resistance coupled between the cathode of the first power up circuit rectifier and an intermediate power up circuit node, and
a first zener diode comprising an anode coupled to the circuit ground and a cathode coupled to the intermediate power up circuit node, and
a transistor comprising a first terminal coupled to the output, a second terminal coupled to the first power up circuit rectifier, and a control terminal coupled to the intermediate power up circuit node with a voltage between the control terminal and the first terminal determining an impedance between the first and second terminals of the transistor to selectively connect the first power up circuit rectifier with the output when the output voltage at the output is less than a zener voltage of the first zener diode and to disconnect the first power up circuit rectifier from the output when the output voltage at the output is greater than the zener voltage of the first zener diode.
9. The driver circuit of claim 5 , further comprising a power up circuit providing power to the PWM controller, the power up circuit comprising:
an input coupleable to an AC input source;
a power up circuit transformer, comprising:
a power up transformer primary winding coupled to the input to receive AC input power from the AC input source,
a first power up transformer secondary winding with a first end coupled to a first power up circuit rectifier and a second end coupled to a circuit ground, and
a second power up transformer secondary winding with a first end coupled with the circuit ground and a second end coupled to a second power up circuit rectifier; and
an output coupled with the first and second power up circuit rectifiers and providing a generally constant output voltage to a power input of the PWM controller independent of a voltage of the AC input power.
10. The driver circuit of claim 9 :
where the first power up circuit rectifier comprises an anode coupled to the first end of the first power up transformer secondary winding and a cathode;
where the second power up circuit rectifier comprises an anode coupled to the second end of the second power up transformer secondary winding and a cathode coupled to the output; and
where the power up circuit further comprises:
a power up circuit resistance coupled between the cathode of the first power up circuit rectifier and an intermediate power up circuit node, and
a first zener diode comprising an anode coupled to the circuit ground and a cathode coupled to the intermediate power up circuit node, and
a transistor comprising a first terminal coupled to the output, a second terminal coupled to the first power up circuit rectifier, and a control terminal coupled to the intermediate power up circuit node with a voltage between the control terminal and the first terminal determining an impedance between the first and second terminals of the transistor to selectively connect the first power up circuit rectifier with the output when the output voltage at the output is less than a zener voltage of the first zener diode and to disconnect the first power up circuit rectifier from the output when the output voltage at the output is greater than the zener voltage of the first zener diode.
11. The driver circuit of claim 1 , further comprising a power up circuit providing power to the PWM controller, the power up circuit comprising:
an input coupleable to an AC input source;
a power up circuit transformer, comprising:
a power up transformer primary winding coupled to the input to receive AC input power from the AC input source,
a first power up transformer secondary winding with a first end coupled to a first power up circuit rectifier and a second end coupled to a circuit ground, and
a second power up transformer secondary winding with a first end coupled with the circuit ground and a second end coupled to a second power up circuit rectifier; and
an output coupled with the first and second power up circuit rectifiers and providing a generally constant output voltage to a power input of the PWM controller independent of a voltage of the AC input power.
12. The driver circuit of claim 11 :
where the first power up circuit rectifier comprises an anode coupled to the first end of the first power up transformer secondary winding and a cathode;
where the second power up circuit rectifier comprises an anode coupled to the second end of the second power up transformer secondary winding and a cathode coupled to the output; and
where the power up circuit further comprises:
a power up circuit resistance coupled between the cathode of the first power up circuit rectifier and an intermediate power up circuit node, and
a first zener diode comprising an anode coupled to the circuit ground and a cathode coupled to the intermediate power up circuit node, and
a transistor comprising a first terminal coupled to the output, a second terminal coupled to the first power up circuit rectifier, and a control terminal coupled to the intermediate power up circuit node with a voltage between the control terminal and the first terminal determining an impedance between the first and second terminals of the transistor to selectively connect the first power up circuit rectifier with the output when the output voltage at the output is less than a zener voltage of the first zener diode and to disconnect the first power up circuit rectifier from the output when the output voltage at the output is greater than the zener voltage of the first zener diode.
13. The driver circuit of claim 12 , where the power up circuit further comprises:
an output capacitance coupled between the output and the circuit ground; and
a second zener diode comprising an anode coupled to the circuit ground, and a cathode coupled to the output.
14. The driver circuit of claim 1 , further comprising an impedance network coupled across the second capacitor between the first end of the secondary winding of the driver transformer and the first driver output.
15. The driver circuit of claim 1 , further comprising an impedance network coupled between the first driver output and the second driver output.
16. The driver circuit of claim 1 , wherein the second capacitor comprises:
a first terminal connected directly to the first end of the secondary winding of the driver transformer; and
a second terminal connected directly to the first driver output.
17. The driver circuit of claim 1 , wherein the first rectifier comprises:
an anode connected directly to the second end of the secondary winding of the driver transformer; and
a cathode connected directly to the first driver output.
18. The driver circuit of claim 1 , wherein the limiting circuit input is connected directly to the PWM output.
19. A universal input power up circuit for providing power to a gate drive controller circuit, the power up circuit comprising:
an input coupleable to an AC input source;
a power up circuit transformer, comprising:
a power up transformer primary winding coupled to the input to receive AC input power from the AC input source,
a first power up transformer secondary winding with a first end coupled to a first power up circuit rectifier and a second end coupled to a circuit ground, where the first power up circuit rectifier comprises an anode coupled to the first end of the first power up transformer secondary winding and a cathode, and
a second power up transformer secondary winding with a first end coupled with the circuit ground and a second end coupled to a second power up circuit rectifier, where the second power up circuit rectifier comprises an anode coupled to the second end of the second power up transformer secondary winding and a cathode coupled to the output, wherein the cathode of the first power up circuit rectifier is not directly connected to the cathode of the second power up circuit rectifier; and
an output coupled with the first and second power up circuit rectifiers and providing a generally constant output voltage to power a gate drive controller circuit independent of a voltage of the AC input power.
20. The power up circuit of claim 19 , wherein the power up circuit further comprises:
a power up circuit resistance coupled between the cathode of the first power up circuit rectifier and an intermediate power up circuit node; and
a first zener diode comprising an anode coupled to the circuit ground and a cathode coupled to the intermediate power up circuit node; and
a transistor comprising a first terminal coupled to the output, a second terminal coupled to the first power up circuit rectifier, and a control terminal coupled to the intermediate power up circuit node with a voltage between the control terminal and the first terminal determining an impedance between the first and second terminals of the transistor to selectively connect the first power up circuit rectifier with the output when the output voltage at the output is less than a zener voltage of the first zener diode and to disconnect the first power up circuit rectifier from the output when the output voltage at the output is greater than the zener voltage of the first zener diode.
21. The power up circuit of claim 20 , further comprising:
an output capacitance coupled between the output and the circuit ground; and
a second zener diode comprising an anode coupled to the circuit ground, and a cathode coupled to the output.
22. The power up circuit of claim 19 , wherein the power up transformer primary winding comprises:
a first end connected directly to a first terminal of the input; and
a second end connected directly to a second terminal of the input.
23. A driver circuit for driving a control terminal of a transistor, the driver circuit comprising:
a first driver output operative to selectively provide a drive signal to a control terminal of a transistor;
a second driver output coupleable to a second terminal of the transistor;
a driver transformer comprising:
a core,
a primary winding wound on the core, and
a secondary winding wound on the core having a first end and a second end coupled with the second driver output;
a pulse width modulation (PWM) controller comprising:
a PWM output, and
a control input;
a first capacitor coupled between a first end of the primary winding of the driver transformer and the PWM output;
a second capacitor coupled between the first end of the secondary winding of the driver transformer and the first driver output;
a first rectifier coupled between the first driver output and the second driver output; and
an impedance network coupled with the second capacitor to facilitate discharging of the second capacitor.
24. The driver circuit of claim 23 , where the impedance network is coupled across the second capacitor between the first end of the secondary winding of the driver transformer and the first driver output.
25. The driver circuit of claim 23 , where the impedance network is coupled between the first driver output and the second driver output.