Freescale Semiconductor,inc.

Tsukasa Hoshi

Hiroshi Sakamoto

Bryce T Osoinach

Eiji Shikata

Toshiaki Ito

Craig R Teegarden

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 light-emitting element drive apparatus for achieving light-emission control of a light-emitting element with high speed and high accuracy includes a monitoring photodiodethat receives light emitted from a laser diodeto generate a current, Im, that corresponds to the optical output thereof. The current Im is converted to a monitor voltage Vm by a current-to-voltage conversion circuit, and its waveform is smoothed by a first low-pass filterto produce a monitoring average value Vav that has a ripple component. A pre-modulated optical power setup voltage Vps generated by a variable direct-current voltage sourceis modulated by a pulse modulation circuitbased on a data signal delayed by a predetermined time, and smoothed via a second low-pass filterand a third low-pass filter. Then, an optical power setup voltage Vref that has a nearly similar amplitude and ripple component is generated in synchronization with the average value Vav.

Light-emitting element drive apparatus

A light-emitting element drive circuit capable of controlling the drive current of a light-emitting element in consideration of changes in a threshold value of the light-emitting element. A laser diodeemits light in accordance with a bias current Ib of a bias current drive circuitand a light-emitting current Ip of a data current drive circuit. A photodiodeoutputs a monitor current Im that corresponds to the optical output of the laser diode. A bias current feedback circuitdetects a change in the threshold current in accordance with the current Im, and outputs a control signal CS. The bias current drive circuitgenerates a bias current Ib that corresponds to the threshold current Ith of the laser diodeafter the change. A light-emitting current feedback circuitdetects a change in the optical output of the laser diodein accordance with the current Im, and outputs a controls signal CS. The data current drive circuitgenerates a light-emitting current Ip relative to a pre-determined optical output of the laser diodein accordance with the control signal CS

Light-emitting element drive circuit

Growing community of inventors

Sendai, Japan

Tsukasa Hoshi