Abstract:
An audio jack may include two contacts to electrically connect to a ground contact of an audio plug in order to detect that a metallic audio plug is inserted into the audio jack. A first of these two contacts may be grounded to form a current return path that generates a ground voltage at the ground contact of the audio plug. The second of these two contacts may be repurposed after the detection to sense the ground voltage. The sensed ground voltage may be added to right and left audio signals. The net voltages provided to the audio plug may be right and left audio signals that include the sensed ground voltage minus the actual ground voltage at the ground contact of the audio plug. This may remove the ground voltage from the net audio output signals, which may reduce crosstalk.
Abstract:
An audio source device has an audio connector to which an external load can be connected. An audio signal is amplified and then driven through the connector, wherein the amplification process uses feedback from the return pin of the connector. The return pin is directly connected to a ground break resistor circuit. The ground break resistor circuit is connected between the return pin of the audio connector and circuit ground. A determination is made as to whether the connected external load has a low impedance or a high impedance. When a low impedance load is detected, such as a headset, the ground break resistor circuit is essentially short-circuited. When a high impedance load is detected, the ground break resistor circuit is maintained and its value is set in accordance with the detected load. Other embodiments are also described.
Abstract:
Circuits, methods, and apparatus for grounding contacts in an audio jack. One example may provide a driver, such as a charge pump, driving a first transistor or switch coupled between a first contact in an audio jack and ground, and a second transistor or switch coupled between a second contact in the audio jack and ground. The first transistor or switch and second transistor or switch may be p-channel transistors or n-channel transistors depletion or enhancement-mode transistors, floating-gate transistors, MEMs, relays, or other switching devices. The first and second transistors or switches may be on and conducting when power is removed from the driver.
Abstract:
Audio jack optical modules that may have a reduced size. Various examples may provide an optical module for an audio jack where a driver circuit is omitted from the optical module and instead placed either elsewhere in the audio jack or separately outside the audio jack. In some examples, the driver may be integrated with a logic circuit, such as a coder-decoder (CODEC) or other logic circuit. Other examples may provide an optical module for an audio jack where a lens for a light-emitting diode is omitted. In some examples, a higher-power light-emitting diode may be used. These light-emitting diodes may be strong enough to provide a requisite amount of light to a detector in, or associated with, an audio plug.
Abstract:
An audio jack may include two contacts to electrically connect to a ground contact of an audio plug in order to detect that a metallic audio plug is inserted into the audio jack. A first of these two contacts may be grounded to form a current return path that generates a ground voltage at the ground contact of the audio plug. The second of these two contacts may be repurposed after the detection to sense the ground voltage. The sensed ground voltage may be added to right and left audio signals. The net voltages provided to the audio plug may be right and left audio signals that include the sensed ground voltage minus the actual ground voltage at the ground contact of the audio plug. This may remove the ground voltage from the net audio output signals, which may reduce crosstalk.
Abstract:
Circuits, methods, and apparatus for grounding contacts in an audio jack. One example may provide a driver, such as a charge pump, driving a first transistor or switch coupled between a first contact in an audio jack and ground, and a second transistor or switch coupled between a second contact in the audio jack and ground. The first transistor or switch and second transistor or switch may be p-channel transistors or n-channel transistors depletion or enhancement-mode transistors, floating-gate transistors, MEMs, relays, or other switching devices. The first and second transistors or switches may be on and conducting when power is removed from the driver.
Abstract:
An audio source device has an audio connector to which an external load can be connected. An audio signal is amplified and then driven through the connector, wherein the amplification process uses feedback from the return pin of the connector. The return pin is directly connected to a ground break resistor circuit. The ground break resistor circuit is connected between the return pin of the audio connector and circuit ground. A determination is made as to whether the connected external load has a low impedance or a high impedance. When a low impedance load is detected, such as a headset, the ground break resistor circuit is essentially short-circuited. When a high impedance load is detected, the ground break resistor circuit is maintained and its value is set in accordance with the detected load. Other embodiments are also described.