Capacitive discharge circuit for touch sensitive screen
First Claim
1. An electronic device, comprising:
- an input line coupled to a sense capacitance of a touch sensitive screen;
a voltage regulator circuit having a supply input node and a regulated node;
a capacitor having first and second terminals;
a first switch circuit having inputs coupled to the regulated node of the voltage regulator circuit and to a common mode node, and an output coupled to the first terminal of the capacitor;
a second switch circuit having inputs coupled to a power supply node and to a ground node, and an output coupled to the second terminal of the capacitor; and
a third switch circuit having inputs coupled to the input line and to the power supply node, and an output coupled to the supply input node of the voltage regulator circuit.
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Accused Products
Abstract
A capacitive discharge circuit includes a line having a capacitance, a switched capacitor circuit including a capacitor, a switched circuit coupled to the line, and a voltage regulator coupled between the switched capacitor circuit and the switched circuit. A controller operates the switched capacitor circuit and switched circuit to in a first phase, charge the capacitor by coupling the capacitor between a common mode and a power supply, and in a second phase, discharge the capacitor by coupling the voltage regulator in series with the capacitor between the power supply node a ground. The controller is also configured to in a third phase, charge the capacitor by coupling the capacitor between the common mode and the power supply, and in a fourth phase, share charge between the line and the capacitor by coupling the voltage regulator and the capacitor in series between the line and the ground.
9 Citations
14 Claims
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1. An electronic device, comprising:
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an input line coupled to a sense capacitance of a touch sensitive screen; a voltage regulator circuit having a supply input node and a regulated node; a capacitor having first and second terminals; a first switch circuit having inputs coupled to the regulated node of the voltage regulator circuit and to a common mode node, and an output coupled to the first terminal of the capacitor; a second switch circuit having inputs coupled to a power supply node and to a ground node, and an output coupled to the second terminal of the capacitor; and a third switch circuit having inputs coupled to the input line and to the power supply node, and an output coupled to the supply input node of the voltage regulator circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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Specification