Current limit controller for an air bag deployment system
First Claim
1. An air bag deployment system, comprising:
- a switch circuit having a first terminal and a second terminal;
a transistor having a base terminal coupled to the first terminal of the switch circuit, a collector terminal coupled to the second terminal of the switch circuit for receiving a first energy, and an emitter terminal for receiving a second energy;
a drive limit controller having a voltage terminal coupled to the emitter terminal of the transistor, a first input terminal, a second input terminal, and an output; and
a transistor having a gate coupled to the output of the drive limit controller, a drain terminal coupled to the second terminal of the switch circuit, and a source terminal that provides the first energy as a deployment energy in the air bag deployment system.
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Accused Products
Abstract
An air bag deployment system (10) generates the proper current to activate a squib (74) and deploy an air bag. A separate capacitor (48) powers circuitry in a drive limit controller (54) for providing a variable voltage drive to a MOS device (68) to regulate squib (74) firing current. A switch circuit (38) supplies gate current to a transistor (46) such that an electrical connecting path allows a capacitor (22) to charge a capacitor (48). During squib (74) firing and air bag deployment, the switch circuit (38) provides electrical isolation between the decaying voltage stored on the capacitor (22) that powers the squib (74) current and the capacitor (48) that provides current regulation to the squib (74) from the drive limit controller (54).
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Citations
17 Claims
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1. An air bag deployment system, comprising:
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a switch circuit having a first terminal and a second terminal; a transistor having a base terminal coupled to the first terminal of the switch circuit, a collector terminal coupled to the second terminal of the switch circuit for receiving a first energy, and an emitter terminal for receiving a second energy; a drive limit controller having a voltage terminal coupled to the emitter terminal of the transistor, a first input terminal, a second input terminal, and an output; and a transistor having a gate coupled to the output of the drive limit controller, a drain terminal coupled to the second terminal of the switch circuit, and a source terminal that provides the first energy as a deployment energy in the air bag deployment system. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An electrical conduction path for an air bag deployment system, comprising:
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a switch circuit having a first terminal for receiving a first stored energy and a second terminal for receiving a second stored energy; and a transistor having a control electrode coupled to the first terminal of the switch circuit, and a current conducting electrode coupled to the second terminal of the switch circuit, wherein the transistor provides an electrical conduction path controlled by the switch circuit, the transistor being off during deployment of an air bag for separating the first stored energy from the second stored energy. - View Dependent Claims (11, 12, 13, 14, 15)
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16. An integrated circuit for air bag deployment, comprising:
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a transistor having a control electrode and a first and a second conducting electrode; a switch circuit having a first terminal coupled to the control electrode of the transistor and a second terminal coupled to the first conducting electrode of the transistor; and a high side current circuit having a first input and a second input, wherein the first input of the high side current circuit is coupled to the first conducting electrode of the transistor and the second input of the high side current circuit is coupled to the second conducting electrode of the transistor, and the transistor isolates the first input from the second input of the high side current circuit when the second terminal of the switch circuit receives a signal for air bag deployment. - View Dependent Claims (17)
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Specification