Driver circuit with controlled gate discharge current
AssigneeSTMicroelectronics R&D (Shanghai) Co. Ltd.
InventorsFei Wang, Wen Li Bai
Life of this patent
Estimating the term…
Abstract
The gate of a drive transistor having a drain and source is discharged by a circuit including a sensing circuit configured to sense a drain-to-source voltage of the drive transistor. A first current sink path is coupled to the gate of the drive transistor. The first current sink path applies a high discharge current to the gate of the drive transistor when the sensing current senses a lower drain-to-source voltage of the drive transistor. A second current sink path is also coupled to the gate of the drive transistor. The second current sink path is configured to apply a low discharge current to the gate of the drive transistor when the sensing current senses a higher drain-to-source voltage of the drive transistor.
Claims23
A circuit for discharging a gate of a drive transistor having a drain and source, comprising:
- a sensing circuit configured to sense a drain-to-source voltage of the drive transistor;
- a first current sink path coupled to the gate of the drive transistor, said first current sink path configured to apply a first discharge current to the gate of the drive transistor when the sensing circuit senses a first drain-to-source voltage of the drive transistor;
- and
- a second current sink path coupled to the gate of the drive transistor, said second current sink path configured to apply a second discharge current, less than the first discharge current, to the gate of the drive transistor when the sensing circuit senses a second drain-to-source voltage of the drive transistor that is greater than the first drain-to-source voltage.
A method for discharging a gate of a drive transistor having a drain and source, comprising:
- sensing a drain-to-source voltage of the drive transistor;
- activating a first current sink path coupled to the gate of the drive transistor to apply a first discharge current to the gate of the drive transistor when the sensed drain-to-source voltage of the drive transistor is lower than a first threshold;
- and
- activating a second current sink path coupled to the gate of the drive transistor to apply a second discharge current, less than the first discharge current, to the gate of the drive transistor when the sensed drain-to-source voltage of the drive transistor is higher than a second threshold.
A circuit, comprising:
- a drive transistor having a gate, drain and source;
- a circuit configured to supply a first current in response to a control signal indicating turn-off of said drive transistor;
- a sense node connected to receive said first current;
- a first circuit path connected between the sense node and the source of the drive transistor, said first circuit path presenting a first voltage drop from the sense node to the source that is dependent on a drain-to-source voltage of the drive transistor;
- a second circuit path connected between the sense node and the source of the drive transistor, said second circuit path presenting a second voltage drop from the sense node to the source that is independent of the drain-to-source voltage of the drive transistor;
- a first current sink path configured to apply a first discharge current to the gate of the drive transistor when the first voltage drop is less than the second voltage drop;
- and
- a second current sink path configured to apply a second discharge current, less than the first discharge current, to the gate of the drive transistor when the second voltage drop is less than the first voltage drop.
A circuit, comprising:
- a drive transistor having a gate, drain and source;
- a circuit configured to supply a first current and a second current in response to a control signal indicating turn-off of said drive transistor;
- a first node connected to receive said first current;
- a second node connected to receive said second current;
- a first current mirroring circuit having an input coupled to the first node and configured to receive the first current and including a first current sink path configured to apply a first discharge current to the gate of the drive transistor;
- a second current mirroring circuit having a common node at the second node and having an input coupled to the drain of the drive transistor, said second current mirroring circuit outputting a third current when a drain-to-source voltage across the drive transistor is less than a threshold;
- and
- a third current mirroring circuit having an input coupled to an output of the second current mirroring circuit and configured to receive the second current and including a second current sink path configured to apply a second discharge current, greater than the first discharge current, to the gate of the drive transistor.
Dependencies are inferred from the claim text.