Apple Inc.

Manisha P Pandya

Asif Hussain

Jingdong Chen

Mohammad Jafar Navabi-Shirazi

Behzad Mohtashemi

Inhwan Oh

Shimon Elkayam

Bharat K Patel

Yanhui Xie

Zaki Moussaoui

Alejandro Lara Ascorra

Kisun Lee

Jun Qi

Nicholas Ainsley Sims

Adrian E Sun

Antoin J Russell

Nileshbhai J Shah

Ji Yeoul Ryoo

Edward H Frank

Weihong Qiu

Kevin Scott Fetterman

Michelle Rae Goldberg

Bogdan Tudor Bucheru

Kathleen A Bergeron

Marco Soldano

Mao Ye

Rohan Dayal

Juan Carlos Pastrana

Sameer G Kelkar

Abby Cherian

Andrew P Aitken

Steve Xing-Fu Zhou

Bharatkumar K Patel

John Douglas Field

Malhar V Bhatt

Harsha Lakshmanan

Deborah Claire Sharrah

A wireless power transmitting device transmits wireless power signals to a wireless power receiving device using an output circuit that includes a wireless power transmitting coil. Measurement circuitry is coupled to the output circuit to help determine whether the wireless power receiving device is present and ready to accept transmission of wireless power. The measurement circuitry includes a measurement circuit that is coupled to the output circuit and that measures signals while oscillator circuitry supplies the output circuit with signals at a probe frequency. The measurement circuitry also includes a measurement circuit that is coupled to the output circuit and that measures signals while the oscillator circuitry sweeps signals applied to the output circuit between a first frequency and a second frequency to detect sensitive devices such as radio-frequency identification devices. Impulse response circuitry in the measurement circuitry is used to make inductance and Q factor measurements.

Wireless charging system with object detection

A power converter can be implemented as a series of power conversion stages, including a wireless power conversion stage. In typical embodiments, the power converter receives power directly from mains voltage and outputs power to a battery within an electronic device. A transmitter side of the power converter converts alternating current received from a power source (e.g., mains voltage) to an alternating current suitable for applying to a primary coil of the wireless power conversion stage of the power converter.

Low-profile power converter

Aspects of the subject technology relate to control circuitry for light-emitting diodes. The control circuitry may operate a light-emitting diode using a multi-peak pulse-width-modulation signal. The control circuitry may include a multi-stage driver having a relatively larger driver stage for providing a direct current through a light-emitting diode and a relatively smaller driver stage configured to cooperate with a pulse-width-modulation controller to pulse-width-modulate a current through the light-emitting diode.

Split driver backlightsystems and methods

A half bridge power converter can be coupled to, or included in, a wireless transmitter device. The half bridge power converter includes an upper switching element connected between a direct current supply voltage and a lower switching element. A duty controller is coupled to the upper and the lower switching elements and is configured to asymmetrically control the duty cycles of the upper and lower switching elements based on a voltage level of the direct current supply voltage. In general, the duty cycle of the lower switching element is different than the duty cycle of the upper switching element. Additionally or alternatively, the duty controller is configured to determine and control the duty cycles of the upper and lower switching elements to adjust a direct current gain of a wireless energy transfer system that includes the wireless transmitter device.

Asymmetric duty control of a half bridge power converter

Aspects of the subject technology relate to display of an electronic device. The display includes a backlight unit having a voltage source, a string of light-emitting diodes and a bypass switch for each light-emitting diode in the string. The string of light-emitting diodes can receive, at a first end, a supply voltage from the voltage source. The bypass switch for each light-emitting diode is controllable to pulse-width-modulate that light-emitting diode. The headroom voltage feedback circuit is coupled to a second end of the string.

Local display backlighting systems and methods

Split driver backlight systems and methods

Aspects of the subject technology relate to control circuitry for light-emitting diodes. The control circuitry includes a two-dimensional light-emitting diode (LED) array. The control circuitry may include a single LED array operable by a common driver or multiple LED arrays each operable by a dedicated LED matrix driver. Each matrix driver may receive a synchronization signal from a common controller and may include a programmable phase lock loop (PLL) to synchronize each matrix driver to the synchronization signal. The LED array may include multiple strings of LEDs mounted in series along the string. Each LED in each string may include a bypass switch operable to modify the current through that LED by pulse-width modulation.

A primary resonant flyback converter may include a primary winding, a resonant capacitor in series with the primary winding, a secondary winding magnetically coupled to the primary winding, and an output electrically coupled to the secondary winding. A main switch may be operated to energize the primary winding when closed and transfer energy stored in the primary winding to the secondary winding when open. An auxiliary switch may be configured to switch complimentarily to the main switch, thereby allowing a resonant current to circulate through the primary winding and capacitor. Switch timing may be controlled to produce a desired output voltage. The switching frequency may be varied as a function of output load, input voltage and/or voltage ripple on a DC bus of the converter. Switching may also be temporarily disabled responsive to a decrease in output load and re-enabled responsive to an increase in output load.

Variable frequency and burst mode operation of primary resonant flyback converters

A power converter includes a buck converter with a low-side switch. During a discharge mode, current passes through the low-side switch to form a current loop. The low-side switch is typically closed synchronously with the opening of a high-side switch coupled to an input voltage level to the buck converter. The power converter also includes a high-side controller and a low-side controller, which together are configured to adjust the timing of the operation mode of the high-side controller between a storage mode and the discharge mode.

Synchronous buck converter with current sensing

Various systems, apparatuses, and methods are disclosed herein, which provide a new power conversion topology for isolated systems that does not include a transformer. Embodiments of the inventive systems comprise: a switching system utilizing high voltage, low leakage switches, e.g., Silicon Carbide (SiC) MOS-FETs; a power source; an inductor and a capacitor operating as a link stage resonant LC circuit; and a load. The switching system may be configured to be controlled in a synchronized 'four phase' control loop process, wherein the input switches are prevented from being closed at the same time as the output switches, thereby providing electrical isolation between the input power source and the load&#x2014;without the use of a transformer. The techniques disclosed herein are applicable to any number of isolated systems that supply power to electronic systems such as: digital cameras, mobile phones, watches, personal data assistants (PDAs), portable music players, displays, and computers.

Transformerless AC line isolator

Various systems and methods are disclosed herein, which provide isolated systems with an auxiliary, multi-signal digital feedback loop for reporting a plurality of different potential fault conditions in an output system (e.g., output short circuit, output over-voltage, output under-voltage, output over temperature, etc.) to a Primary Controller in an input system. The signals may be sent according to any desired standardized (or proprietary) data transmission protocols. Use of a digital feedback loop allows the signals to be passed to the Primary Controller more quickly than is allowed by traditional analog feedback paths&#x2014;and while using only a single optocoupler device for the transmission of all fault conditions. The techniques disclosed herein are applicable to any number of isolated systems that supply power to electronic systems such as: digital cameras, mobile phones, watches, personal data assistants (PDAs), portable music players, monitors, as well as desktop, laptop, and tablet computers.

Multi-signal digital controller for isolated system feedback loop

A backlight driver chip for an electronic device includes an input that receives data corresponding to a brightness of a backlight device. The backlight driver chip also includes correction circuitry that determines an amplitude correction factor based at least in part on the data and the brightness of the backlight device. The correction circuitry also determines a corrected brightness based at least in part on the amplitude correction factor. The backlight driver chip further includes an output that provides a current signal that drives the backlight device, wherein the current signal is based at least in part on the corrected brightness.

Devices and methods for controlling brightness of a display backlight

This application relates to systems, methods, and apparatus for controlling a switching frequency of a boost or flyback converter to be above an audible frequency range when operating the boost or flyback converter in a pulse frequency modulation (PFM) mode. The boost or flyback converter uses one or more switches for converting power for a display panel. In order to boost the switching frequency when operating in the PFM mode, the boost or flyback converter can selectively implement certain current and/or voltage limits for pulses that are generated as a result of the switching. The current and/or voltage limits can be set according to a load of the boost or flyback converter, and a correspondence between the current and/or voltage limits and the loads can be stored in a lookup table accessible to the boost or flyback converter.

PFM scheme for boost and flyback converter in LED backlight application

An electronic device has an I/O port, a bus connector and a transistor that is connected between the I/O port and a communications contact of the bus connector. A control circuit is connected to the transistor to maintain a gate voltage of the transistor independent of power supply voltage on a power supply contact of the connector. Other embodiments are also described and claimed.

Growing community of inventors

Sunnyvale, CA, United States of America

Manisha P Pandya