Apple Inc.

Fabio Ongaro

Michael Couleur

Bogdan-Eugen Matei

Giovanni Saccomanno

Nicola Rasera

Cristian Grecu

Dashun Xue

Alessandro Molari

Yesim Inam

Ming Sun

Hao Zhou

Xiaofeng Wang

Siarhei Meliukh

Nikola Jovanovic

Frank Trautmann

Johan L Piper

Angelo Bassi

Denis M Darmon

Robert D Zucker

Miguel A Dos Santos

A piecewise linear current-mode digital-to-analog converter circuit approximates an exponential output current over a range of input codes by generating linearly varying currents with different slopes of different ranges of the input codes. The piecewise linear current-mode digital-to-analog converter circuit includes a current generator circuit that generates the output current based on a reference voltage and a feedback signal. A variable resistance circuit is used to generate the feedback signal using the output current. Respective values of the reference voltage and the variable resistance circuit vary as a function of the input code.

Piecewise linear digital-to-analog converter circuit

A high current, low dropout driver circuit is disclosed. The circuit includes a decoder configured to decode a plurality of control bits to generate a plurality of control signals, and a current source having a plurality of devices. The current source is configured to activate at least a subset of the plurality of devices using the control signals to provide a load current to a load circuit, such as a light-emitting diode (LED), using activated ones of the plurality of devices and a control voltage. A control circuit is configured to generate the control voltage based on the load current and a reference current.

High current, low dropout driver circuit

Systems and methods for electronic displays to use reference voltages to control driving current of illuminators are provided. The reference voltages are used to reduce or eliminate cross talk in driving voltages among different illuminators and driving voltage variations from frame to frame. The transient performance of the driving current of the illuminator (e.g., the current rise/decline time, current overshoot issue, current settling time) may be improved by implementing the reference voltages.

Method and apparatus for LED driver to reduce cross talk or flicker

A dual-stage boost converter is disclosed. The boost converter includes a charge pump and a boost stage. The charge pump is coupled between an input voltage source and the boost stage. The charge pump is coupled to receive the input voltage and configured to generate an intermediate voltage that is greater than the input voltage received from the input voltage source. The boost stage includes an inductor coupled to receive the intermediate voltage and is configured to generate an output voltage that is greater than or equal to the intermediate voltage.

Dual-stage boost converter

The present disclosure is directed to a pulse frequency modulation (PFM) control method for a boost converter and apparatus for carrying out the method. A boost converter includes an inductor and a transistor coupled thereto. A control circuit is arranged to control the transistor to cause current pulsed to be sourced through the inductor. When operating in a PFM mode, the control circuit may control the timing of pulses such that, at the beginning of a specified time period, current pulses may be sourced with no spacing between successive pulses. After a desired number of pulses have been sourced, no pulses are sourced for the remainder of the specified time period. Nevertheless, the number of pulses sourced over the time period corresponds to a desired average frequency of pulses.

PFM control method for boost converters

A DC-DC converter providing adaptive peak current control is disclosed. A DC-DC converter includes an inductor having first and second terminals coupled to a voltage source and a transistor, respectively. The DC-DC circuit further includes a control circuit configured to control activation of the transistor. A first control block of the control circuit controls the transistor (and thus the inductor peak current) using pulse frequency modulation (PFM). A second control block controls the transistor using pulse width modulation (PWM) and PFM. In a first mode of operation, the control circuit activates the transistor, using PFM, such that the peak-to-peak current through the inductor has a fixed value. In a second mode of operation, the control circuit activates the transistor such that the peak-to-peak current through the inductor is modulated, using both PWM and PFM.

Method and apparatus for providing adaptive inductor peak current in DC-DC converter

A power converter circuit that includes a switch node coupled to a regulated power supply node via an inductor may, in response an assertion of a control signal, source current to the regulated power supply node. In response to initiating a charge cycle, a control circuit may assert the control signal. During an assertion of the control signal, the control circuit may adjust a slope of a transition of the control signal using a voltage level of the switch node.

Power converter with overshoot compensation for a switching device

A power converter circuit that includes a switch node coupled to a regulated power supply node via an inductor may, during a charge cycle, source current to the switch node, and source a bypass current to the regulated power supply node using a regulator control signal. A control circuit may initiate the charge cycle using a first reference voltage level and a sensed inductor current, and generate the regulator control signal using a second reference voltage level and a voltage level of the regulated power supply node.

Power converter with high duty cycle compensation

Systems, apparatuses, and methods for efficiently generating a stable output for a transient load for one or more components are described. In various embodiments, a power converter includes two feedback loops to separate the stability and the equivalent output resistance, which allows the bandwidth to increase. The first loop includes a compensator receiving an output current of an amplifier. Additionally, a first converter and a first current mirror generate a target current based on the output current of the amplifier. Based on the target current, multiple step-down converters generate an output voltage, which is returned to the amplifier through a resistor. The second loop includes a second converter with a first order series RC filter to reduce the second loop's response time. A second current mirror receives current from the second converter and generates a dynamically adapting feedback current, which flows through the resistor in the first loop.

DC-DC converter with a dynamically adapting load-line

A regulator circuit that employs coupled inductors with on-time modulation is disclosed. The regulator circuit includes a driver circuit coupled via first and second inductors to a power supply node of a load circuit, and may charge the power supply node via the first inductor for a first charging period, and charge the power supply node via the second inductor for a second charging period. A control circuit may determine durations of the first and second charging periods using respective pluralities of currents.

On-time modulation for phase locking in a buck converter using coupled inductors

Systems, apparatuses, and methods for generating a stable output voltage for one or more components by checking feedback information for an entire clock period are described. In various embodiments, a power converter generates an output voltage for one or more components. When the load current drawn by the one or more components changes, an inductor current of a low pass filter and monitored by a current sense amplifier also changes. The clock period is divided into a high phase and a low phase with one of the phases being a relatively short phase. During the relatively short phase, the current sense amplifier does not have sufficient time to measure feedback information. Instead of selecting a voltage output of the current sense amplifier, control logic selects a voltage output of a voltage generator, which emulates a voltage ramp with a slope of the inductor current during the relatively short phase.

Systems and methods for generating a feedback current in a DC-DC converter

An apparatus includes a plurality of pulse control circuits and a control circuit. A given pulse control circuit of the plurality of pulse control circuits may source a current pulse to the output power signal based on a comparison of a particular feedback signal of a plurality of feedback signals and a target voltage signal. The control circuit may offset a voltage level of each feedback signal of a first subset of the plurality of feedback signals. The first subset may exclude a first feedback signal. In response to a determination that a period of time has ended, the control circuit may offset a voltage level of each feedback signal of a second subset of the plurality of feedback signals. The second subset may include the first feedback signal and exclude a second feedback signal.

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Munich, Germany

Fabio Ongaro