ADAPTIVE CAPACITIVE TOUCH SENSE CONTROL CIRCUIT
First Claim
1. An adaptive capacitive touch sense control circuit, comprising a voltage buffer, a current setting resistor, a current mirror, a capacitor, a start comparator, an end comparator and a time-to-digital converter, with the voltage buffer being connected with the current setting resistor and the current mirror, the capacitor being connected with the current mirror, the start comparator and the end comparator, and the start comparator and the end comparator being connected with the time-to-digital converter, wherein the capacitor is connected with the current setting resistor;
- the control circuit further comprises a latch provided with a first control switch between the capacitor and the current mirror and between the voltage buffer and the current setting resistor and a second control switch between the capacitor and the current setting resistor; and
the current setting resistor is switched between the ground and a voltage source through a switching element, so that when the current setting resistor is grounded, the first control switch is closed and the second control switch is opened, and when the current setting resistor is connected with the voltage source, the second control switch is closed and the first control switch is opened.
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Abstract
An adaptive capacitive touch sense control circuit includes a voltage buffer, a current setting resistor, a current mirror, a capacitor, a start comparator, an end comparator and a time-to-digital converter. The capacitor is connected with the current setting resistor. The circuit further includes a latch with a first control switch and a second control switch. The current setting resistor is switched between the ground and a voltage source through a switching element, so that when the current setting resistor is grounded, the first control switch is closed and the second control switch is opened, and when the current setting resistor is connected with the voltage source, the second control switch is closed and the first control switch is opened. An adaptive charging mode is adopted to sense a capacitance variation with a great ability of interference recognition, a simple structure, low power consumption and real time processing.
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Citations
12 Claims
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1. An adaptive capacitive touch sense control circuit, comprising a voltage buffer, a current setting resistor, a current mirror, a capacitor, a start comparator, an end comparator and a time-to-digital converter, with the voltage buffer being connected with the current setting resistor and the current mirror, the capacitor being connected with the current mirror, the start comparator and the end comparator, and the start comparator and the end comparator being connected with the time-to-digital converter, wherein the capacitor is connected with the current setting resistor;
- the control circuit further comprises a latch provided with a first control switch between the capacitor and the current mirror and between the voltage buffer and the current setting resistor and a second control switch between the capacitor and the current setting resistor; and
the current setting resistor is switched between the ground and a voltage source through a switching element, so that when the current setting resistor is grounded, the first control switch is closed and the second control switch is opened, and when the current setting resistor is connected with the voltage source, the second control switch is closed and the first control switch is opened. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
- the control circuit further comprises a latch provided with a first control switch between the capacitor and the current mirror and between the voltage buffer and the current setting resistor and a second control switch between the capacitor and the current setting resistor; and
Specification