Technique for drive current stabilization of an automotive ignition system
View Patent ↗Drive current stabilization is achieved through the management of a drive current. The drive current may include a control current that is provided to a control terminal of a switch, a current limit input current that is provided to a current limit circuit associated with the switch and a stabilization current. The switch carries a load current responsive to a control signal on the control terminal. The magnitude of the control current is monitored and a magnitude of the stabilization current is increased responsive to a decrease in the magnitude of the control current to substantially maintain a magnitude of the drive current.
1. An automotive subsystem, comprising:
an ignition coil including a primary winding having a first side and a second side, wherein the first side of the primary winding is coupled to a power source;
a switch including a first output terminal, a second output terminal and a control terminal, wherein the first output terminal is coupled to the second side of the primary winding and the second output terminal is coupled to a common return;
a current source providing a drive current; and
a drive current stabilization circuit coupled between the current source and the control terminal of the switch, wherein the drive current stabilization circuit divides the drive current into a control current that is provided to the control terminal of the switch, a current limit input current that is provided to a current limit circuit associated with the switch and a stabilization current, and wherein the switch carries a load current responsive to a magnitude of a control signal on the control terminal, where the magnitude of the stabilization current is increased responsive to a decrease in a magnitude of the control current to substantially maintain a magnitude of the drive current.
2. The subsystem of claim 1 , wherein the drive current stabilization circuit reduces the magnitude of the stabilization current responsive to an increase in the magnitude of the current limit input current to substantially maintain a magnitude of the drive current.
3. The subsystem of claim 1 , wherein the switch is one of an insulated-gate bipolar transistor (IGBT) or a field-effect transistor (FET).
4. An automotive subsystem, comprising:
an ignition coil including a primary winding having a first side and a second side, wherein the first side of the primary winding is coupled to a power source;
a switch including a first output terminal, a second output terminal and a control terminal, wherein the first output terminal is coupled to the second side of the primary winding and the second output terminal is coupled to a common return;
a current source providing a drive current; and
a drive current stabilization circuit coupled between the current source and the control terminal of the switch, wherein the drive current stabilization circuit divides the drive current into a control current that is provided to the control terminal of the switch and a stabilization current, and wherein the switch carries a load current between the first and second output terminals responsive to a control signal on the control terminal, where the magnitude of the stabilization current is increased responsive to a decrease in a magnitude of the control current to substantially maintain a magnitude of the drive current.
5. The subsystem of claim 4 , wherein the drive current further includes a current limit input current that is provided to a current limit circuit.
6. The subsystem of claim 5 , wherein the current limit circuit monitors the load current through the switch and increases the current limit input current when the load current obtains a desired level.
7. The subsystem of claim 5 , wherein the drive current stabilization circuit reduces the magnitude of the stabilization current responsive to an increase in the magnitude of the current limit input current to substantially maintain a magnitude of the drive current.
8. The subsystem of claim 4 , wherein the switch is one of an insulated-gate bipolar transistor (IGBT) or a field-effect transistor (FET).