Freescale Semiconductor,inc.

Eiji Shikata

Bryce T Osoinach

Toshiaki Ito

Craig R Teegarden

Tsukasa Hoshi

Katsuaki Morishita

Keiji Tenaka

Embodiments include capacitive touch sensors and methods for configuring capacitive touch sensors. A capacitive touch sensor embodiment includes an analog-to-digital converter (ADC) and a controller. The ADC receives an analog voltage signal from an electrode, and samples the analog voltage signal to produce a plurality of digital values. The controller performs a first charging process by supplying the electrode with a first charging current for a first charging interval, and the controller determines, based on the digital values, whether a first electrode voltage value meets a criteria. If not, the controller performs a configuration process that results in setting a second charging current and a second charging interval for the electrode which, in response to performing a second charging process, results in a second electrode voltage value that meets the criteria.

Capacitive touch sensor device configuration systems and methods

A self-calibrating oscillator that increases the output frequency accuracy without using a charge pump includes an oscillation circuit, a pulse counter, a charging circuit, a reset circuit, a calibration circuit, and a timing control unit. The pulse counter counts a pulse signal having frequency ffrom the oscillation circuit based on a count start signal provided from the timing control unit, while providing an output signal to the charging circuit. The charging circuit connects a constant current source and capacitor when provided with the output signal to raise the voltage at the connection node. The calibration circuit provides the oscillation circuit with a calibration value for increasing the frequency if the voltage when the output of the output signal ends is higher than a high potential reference voltage and provides a calibration value for lowering the frequency if this voltage is lower than a low potential reference voltage.

Self-calibrating oscillator

A regulator circuit for efficiently and accurately outputting a target voltage with a simple circuit configuration. The regulator circuit includes an output circuit, a comparator, a counter block, a latch block, and a decoder block. When the target voltage is applied to an output terminal of the output circuit, the output circuit supplies the comparator with feedback voltage. Further, the feedback signal is provided to the counter block. The counter block performs counting in correspondence with the feedback signal. The latch block holds the signal acquired from the counter block and provides the held signal to the decoder block. The decoder block supplies the comparator with reference voltage. The comparator compares the reference voltage and the feedback voltage and controls the counting.

Regulator circuit

A capacitance detection circuit that compensates for the fluctuation of a reference voltage with a simple structure. A C-V circuit for a sensor element generates a detection signal by amplifying a capacitance change value of the sensor element by a predetermined gain based on a reference voltage. A voltage compensation circuit, which is connected to the C-V circuit and supplies a reference voltage to the C-V circuit, reduces the gain relative to a deviation amount when the reference voltage fluctuates by a predetermined deviation amount.

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Sendai, Japan

Eiji Shikata