HIGHLY ACCURATE SYNCHRONIZED CHARGE PUMP FOR CAPACITIVE TOUCH SCREEN SYSTEM
First Claim
1. A touch screen controller, comprising:
- a driver circuit configured to apply a drive signal to a drive line of a capacitive touch sensing panel, the driver circuit being powered by an accurate supply voltage; and
a driver supply circuit configured to receive an input supply voltage and output the accurate supply voltage, the driver supply circuit comprising;
a clocked comparator configured to compare a divided version of the accurate supply voltage to a reference voltage and to output a comparison signal based thereupon; and
a voltage control circuit configured to generate the accurate supply voltage in response to the comparison signal;
wherein the clocked comparator and voltage control circuit are both clocked by a driver supply circuit clock.
1 Assignment
0 Petitions
Accused Products
Abstract
Disclosed herein is a touch screen controller including a driver circuit applying a drive signal to a drive line of a capacitive touch sensing panel. The driver circuit is powered by an accurate supply voltage. A driver supply circuit receives an input supply voltage and outputs the accurate supply voltage. The driver supply circuit includes a clocked comparator comparing a divided version of the accurate supply voltage to a reference voltage and outputting a comparison signal based thereupon. A voltage control circuit (e.g. a charge pump circuit) generates the accurate supply voltage in response to the comparison signal. The clocked comparator and voltage control circuit are both clocked by a driver supply circuit clock.
3 Citations
19 Claims
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1. A touch screen controller, comprising:
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a driver circuit configured to apply a drive signal to a drive line of a capacitive touch sensing panel, the driver circuit being powered by an accurate supply voltage; and a driver supply circuit configured to receive an input supply voltage and output the accurate supply voltage, the driver supply circuit comprising; a clocked comparator configured to compare a divided version of the accurate supply voltage to a reference voltage and to output a comparison signal based thereupon; and a voltage control circuit configured to generate the accurate supply voltage in response to the comparison signal; wherein the clocked comparator and voltage control circuit are both clocked by a driver supply circuit clock. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A driver supply circuit for powering a driver circuit of a touch screen controller, the driver supply circuit, comprising:
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a voltage control circuit configured to generate an accurate supply voltage from an input supply voltage, the voltage control circuit being controlled via a comparison signal; and a comparator configured to compare a divided version of the accurate supply voltage to a reference voltage and to output the comparison signal based thereupon; wherein operation of the voltage control circuit and clocked comparator is synchronized. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
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16. A circuit, comprising:
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a clocked comparator having a clock input receiving a clock signal, a non-inverting input, and an inverting input; a charge pump circuit powered by an input supply voltage and outputting a boosted supply voltage, the charge pump circuit being clocked by the clock signal; a voltage divider coupled between the boosted supply voltage and ground; wherein the inverting input of the clocked comparator is coupled to a tap of the voltage divider; and an impedance circuit coupled between the input supply voltage and ground; wherein the non-inverting input of the clocked comparator is coupled to a tap of the impedance circuit. - View Dependent Claims (17, 18)
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19. A method, comprising:
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powering a driver circuit with an accurate supply voltage; applying a generated by the driver circuit to a drive line of a capacitive touch sensing panel; and changing an input supply voltage to the accurate supply voltage by; in response to an edge of a driver supply circuit clock, comparing a divider version of the accurate supply voltage to a reference voltage and outputting a comparison signal based thereupon; and in response to the edge of the driver supply circuit clock, generating the accurate supply voltage in response to the comparison signal.
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Specification