Abstract: A multi-stage DC-DC power converter includes a first switched-capacitor stage driven by an input voltage. A second switched-capacitor stage is coupled to the first switched-capacitor by an inductor coupling current source. A controller controls charging and discharging of a flying capacitor by the inductor coupling current source in each of the first and second switched-capacitor stages. The controller operates such that each of the flying capacitors of the first and second switched-capacitor stages is soft charged by the inductor coupling current source and a frequency of a switched voltage across the inductor coupling current source is maintained to be high enough to limit inductor current ripple to be negligible compared to its DC component and ensure average inductor current is effectively reduced by factor equal to a voltage conversion ratio of the second switched-capacitor stage.

Abstract: Electronic devices may be provided with audio circuits and circuitry configured to support communications and test mode operations. During normal operation, a standards-compliant connector such as an audio connector may be inserted into a connector port in an electronic device. The audio connector may be associated with a headset or other accessory and may be used to carry audio signals. During test mode operations, a nonstandard test connector may be inserted into the connector port. The electronic device may detect the presence of the nonstandard connector and may direct the electronic device to operate in a testing mode.

Abstract: Electronic devices may be provided with audio circuits and circuitry configured to support communications and test mode operations. During normal operation, a connector such as an audio connector may be inserted into a connector port in an electronic device. The audio connector may be associated with a headset or other accessory and may be used to carry audio signals. During test mode operations, a tester may be coupled to the connector port using an audio connector. The tester may generate voltages, resistances, time-varying signals, or other input that directs the device to configure switching circuitry to support testing. Monitoring circuitry in the device may be used to detect input from the tester. In response to detected input from the tester, the switching circuitry may be adjusted to couple a control circuit that supports test mode operations to the audio connector.

Abstract: Electronic devices may be provided with audio circuits and controller circuitry configured to support test mode operations. A connector such as a reversible connector may be inserted into a mating device connector in an electronic device. The reversible connector may be connected to the device connector in either a normal orientation or a reversed orientation in which the reversible connector is rotated 180° with respect to the normal orientation. During test mode operations, a tester may be coupled to the device connector using the reversible connector. The tester may generate voltages, resistances, time-varying signals, or other input that directs the device to configure switching circuitry to support testing. Monitoring circuitry in the device may be used to detect input from the tester. In response to detected input from the tester, the switching circuitry may be adjusted to couple the controller to the device connector.

Abstract: Circuits, methods, and apparatus that provide an audio receptacle that can detect the presence of an audio jack without using mechanical switches or other such mechanical mechanisms. One example provides an audio receptacle having two contacts that may be electrically connected when an audio jack is inserted. When no audio jack is inserted into the audio receptacle, the two ground contacts may not be connected. When an audio jack is inserted into the audio receptacle, the resulting closed circuit may be detected and used to activate or otherwise turn on one or more audio circuits in or associated with the audio receptacle. Conversely, when no audio jack is inserted, the resulting open circuit may be detected and used to deactivate or otherwise turn off or reduce power in one or more audio circuits in or associated with the audio receptacle.