Capacitive discharge circuit for touch sensitive screen
First Claim
1. A circuit, comprising:
- a voltage regulator circuit having an input node and a regulated node, wherein the input node is coupled to a line having a capacitance;
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; and
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.
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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.
13 Citations
18 Claims
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1. A circuit, comprising:
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a voltage regulator circuit having an input node and a regulated node, wherein the input node is coupled to a line having a capacitance; 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; and 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. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A system, comprising:
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a line coupled to a sense line of a capacitive sensing panel having a capacitance; an analog processing circuit having an input coupled to said line, said analog processing circuit configured to sense said capacitance; and a discharge circuit configured to discharge said capacitance, the discharge circuit comprising; a voltage regulator circuit having an input node and a regulated node, wherein the input node is coupled to said line; a capacitor having first and second terminals; and switching circuitry configured to charge said capacitor during one phase of operation and connect said capacitor to the regulated node in order to share charge between said capacitance and said capacitor during another phase of operation. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A circuit, comprising:
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a voltage regulator circuit having an input node and a regulated node, wherein the input node is coupled to a line having a capacitance; a capacitor having first and second terminals; and switching circuitry configured to charge said capacitor during one phase of operation and connect said capacitor to the regulated node in order to share charge between said capacitance and said capacitor during another phase of operation. - View Dependent Claims (14, 15, 16, 17, 18)
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Specification