Abstract: Techniques and apparatus for driving the gate of a high-side transistor in a switched-mode power supply (SMPS) circuit, such as an inverting buck-boost converter or a buck converter. One example technique to pull down the gate voltage of the high-side transistor involves a multi-step approach, in which the gate voltage is initially discharged to a lower voltage level, and once the gate voltage falls below a certain level, an auxiliary switch can take over to completely turn off the high-side transistor. One example SMPS circuit generally includes a high-side transistor, a pulldown gate driver having an output coupled to a gate of the high-side transistor, a pulse generator having an output coupled to an input of the pulldown gate driver, and a first switch coupled between the gate and a source of the high-side transistor.

Abstract: Techniques and apparatus for driving transistor gates of a switched-mode power supply (SMPS) circuit. One example power supply circuit generally includes a switching converter having a switching transistor and a gate driver having an output coupled to a gate of the switching transistor. The gate driver includes a first switching device coupled between the output of the gate driver and a first voltage rail; a second switching device coupled between the output of the gate driver and a voltage node of the gate driver; a third switching device coupled between the voltage node of the gate driver and a second voltage rail; and a voltage clamp coupled in series with a fourth switching device, the voltage clamp and the fourth switching device being coupled between a third voltage rail and the voltage node (or the output of the gate driver).

Abstract: Innovative techniques to design and generate haptics waveforms are proposed. The proposed techniques reduce or eliminate audible noises being generated by a haptic actuator during operation. A haptic controller may compose a voltage waveform at a resonant frequency of the haptic actuator and generate a corresponding control signal. Instead of suddenly entering a high impedance state from a driving state, the voltage waveform may include a ramp down portion in which the voltage ramps down continuously but quickly so that the current flowing within the actuator is brought down before entering the high impedance state. In this way, audible noises may be reduced or even eliminated.

Abstract: Innovative techniques to design and generate haptics waveforms are proposed. The proposed techniques reduce or eliminate audible noises being generated by a haptic actuator during operation. A haptic controller may compose a voltage waveform at a resonant frequency of the haptic actuator and generate a corresponding control signal. Instead of suddenly entering a high impedance state from a driving state, the voltage waveform may include a ramp down portion in which the voltage ramps down continuously but quickly so that the current flowing within the actuator is brought down before entering the high impedance state. In this way, audible noises may be reduced or even eliminated.

Abstract: Certain aspects of the present disclosure generally relate to electronic circuits and, more particularly, to a power supply circuit and techniques for voltage regulation. One example method for voltage regulation is performed by a switched-mode power supply (SMPS). The method generally includes charging a first capacitive element during a first discharge phase of the SMPS having a first voltage rail and a second voltage rail, the first voltage rail being separate from the second voltage rail. Charging the first capacitive element may include directing a first current to flow from the second voltage rail to a reference potential node through the first capacitive element. In some aspects, the method also includes generating an output voltage at the output node during a first charge phase by directing a second current to flow from the first voltage rail to an inductive element of the SMPS through the first capacitive element.

Abstract: Abstract: In some aspects, a controller may obtain a back electromotive force (BEMF) signal associated with a haptic feedback component, wherein the BEMF signal is generated by movement of the haptic feedback component. The controller may determine a time length for the BEMF signal to cross an amplitude-based window. The controller may determine, based on the time length, a braking amplitude for a control signal to reduce an energy level of the haptic feedback component. The controller may control the control signal according to the braking amplitude. Numerous other aspects are provided.

Abstract: In some implementations, a measurement circuit may drive, using a first transistor, a first node of a haptic load. The measurement circuit may trigger a first comparator when a voltage driving the haptic load satisfies a first condition. The first comparator may have a first node connected, in parallel, to a drain of a second transistor and may have a second node connected to the first node of the haptic load. Additionally, the second transistor may have a gate connected to a gate of the first transistor and may have the drain connected to a first reference current.

Abstract: An apparatus is disclosed for a switch-mode power supply with a network of flying capacitors and switches. In an example aspect, the apparatus includes a switch-mode power supply with an inductor, a switching circuit, and a network of flying capacitors and switches. The switching circuit is coupled to the inductor. The network of flying capacitors and switches is coupled to the switching circuit and includes at least two flying capacitors and multiple switches. The multiple switches are configured to selectively connect the at least two flying capacitors in parallel between a first terminal of the network of flying capacitors and switches and a second terminal of the network of flying capacitors and switches or connect the at least two flying capacitors in series between the first terminal and the second terminal.

Abstract: An apparatus is disclosed for voltage regulation. In example implementations, an apparatus includes a battery subsystem having a first terminal, a second terminal, a third terminal, and at least one battery. The apparatus also includes a voltage regulator that is coupled to the first terminal, the second terminal, and the third terminal. The voltage regulator includes multiple switches, an energy storage unit, and control circuitry. The multiple switches include a first switch coupled to the first terminal, a second switch coupled to the second terminal, and a third switch coupled to the third terminal. The energy storage unit is coupled to the multiple switches. The control circuitry is coupled to the multiple switches and is configured to selectively couple the energy storage unit to the first terminal via the first switch, the second terminal via the second switch, or the third terminal via the third switch.

Abstract: Certain aspects are directed to a circuit for brightness control. The circuit generally includes: a duty cycle adjustment circuit configured to receive a first backlight control signal having a first duty cycle and generate a second backlight control signal having a second duty cycle, the second duty cycle being greater than the first duty cycle if the first duty cycle is less than a threshold; a digital processor configured to set a value of a software brightness code based on the second duty cycle; and a backlight control circuit configured to drive a backlight in accordance with the software brightness code and the second duty cycle of the second backlight control signal.

Abstract: Disclosed are various techniques operating a linear resonant actuator (LRA). In some aspects, a method for operating an LRA includes generating an LRA control signal having a period, the period having an active portion and a high-Z portion according to a duty cycle; detecting, during the high-Z portion of the period, a back electromotive force (BEMF) threshold voltage crossing time and zero voltage crossing time; calculating a period; calculating a BEMF measurement window; calculating a target duty cycle based on the period, the BEMF measurement window, and a margin time; and adjusting the duty cycle of the LRA control signal towards the target duty cycle.

Abstract: In some implementations, a measurement circuit may drive, using a first transistor, a first node of a haptic load. The measurement circuit may trigger a first comparator when a voltage driving the haptic load satisfies a first condition. The first comparator may have a first node connected, in parallel, to a drain of a second transistor and may have a second node connected to the first node of the haptic load. Additionally, the second transistor may have a gate connected to a gate of the first transistor and may have the drain connected to a first reference current.

Abstract: Techniques and apparatus for driving transistor gates of a switched-mode power supply (SMPS) circuit. One example power supply circuit generally includes a switching converter having a switching transistor and a gate driver having an output coupled to a gate of the switching transistor. The gate driver includes a first switching device coupled between the output of the gate driver and a first voltage rail; a second switching device coupled between the output of the gate driver and a voltage node of the gate driver; a third switching device coupled between the voltage node of the gate driver and a second voltage rail; and a voltage clamp coupled in series with a fourth switching device, the voltage clamp and the fourth switching device being coupled between a third voltage rail and the voltage node (or the output of the gate driver).

Abstract: Disclosed are various techniques operating a linear resonant actuator (LRA). In some aspects, a method for operating an LRA includes generating an LRA control signal having a period, the period having an active portion and a high-Z portion according to a duty cycle; detecting, during the high-Z portion of the period, a back electromotive force (BEMF) threshold voltage crossing time and zero voltage crossing time; calculating a period; calculating a BEMF measurement window; calculating a target duty cycle based on the period, the BEMF measurement window, and a margin time; and adjusting the duty cycle of the LRA control signal towards the target duty cycle.

Abstract: Certain aspects are directed to a circuit for brightness control. The circuit generally includes: a duty cycle adjustment circuit configured to receive a first backlight control signal having a first duty cycle and generate a second backlight control signal having a second duty cycle, the second duty cycle being greater than the first duty cycle if the first duty cycle is less than a threshold; a digital processor configured to set a value of a software brightness code based on the second duty cycle; and a backlight control circuit configured to drive a backlight in accordance with the software brightness code and the second duty cycle of the second backlight control signal.

Abstract: Certain aspects of the present disclosure generally relate to methods and apparatus for switching between modes of a multi-mode power supply circuit. One example power supply circuit generally includes a switched-mode power supply (SMPS) circuit, a voltage regulator circuit having an input coupled to an output of the SMPS circuit, the voltage regulator circuit being configured to be selectively enabled, a first voltage divider selectively coupled to the output of the SMPS circuit and selectively coupled to an output of the voltage regulator circuit, and a second voltage divider coupled to the output of the voltage regulator circuit.

Abstract: Certain aspects of the present disclosure generally relate to a switch mode power supply (SMPS). The SMPS generally includes at least one switch, an inductive element coupled to the at least one switch, and control circuitry, the control circuitry being configured to control the at least one switch, during each switching cycle of a plurality switching cycles of the SMPS, to transfer charge from an input voltage (Vin) node of the SMPS to the inductive element during an on-time of the switching cycle and transfer the charge to an output voltage (Vout) node of the SMPS during an off-time of the switching cycle. The on-time may be set based on a duty ratio of the SMPS, the duty ratio representing a ratio between a voltage at the Vin node and a voltage at the Vout node, the on-time being fixed depending on the duty ratio of the SMPS.

Abstract: Certain aspects of the present disclosure generally relate to methods and apparatus for switching between modes of a multi-mode power supply circuit. One example power supply circuit generally includes a switched-mode power supply (SMPS) circuit, a voltage regulator circuit having an input coupled to an output of the SMPS circuit, the voltage regulator circuit being configured to be selectively enabled, a first voltage divider selectively coupled to the output of the SMPS circuit and selectively coupled to an output of the voltage regulator circuit, and a second voltage divider coupled to the output of the voltage regulator circuit.