Apple Inc.

Steven E Austin

Lawrence F Heyl

James J Blanc

Stephen J Kim

David B Townsley

Mark C Gurries

A novel battery monitoring device is described. The monitoring device determines amount of battery self-discharge, determines amount of battery discharge from a monitoring circuit, determines amount of battery discharge from a host device when the host device is in a first power consumption mode, and determines amount of battery discharge from the host device when the host device is in a second power consumption mode. The first mode causes greater discharge of the battery during a given period of time than the second mode.

Method and apparatus for monitoring discharge of a battery device based

An open-loop speaker amplifier and a dynamic range reduction circuit are disclosed. The speaker amplifier includes a bridge driver and a bridge circuit. The bridge circuit includes a first set of switches and a second set of switches. When the first set of switches are activated, a positive current flows through a speaker load. When the second set of switches are activated, a negative current flows through the speaker load. The bridge driver generates a pulse width modulated signal and a delayed pulse width modulated signal to drive the first and second set of switches of the bridge circuit responsive to a modulation signal. The modulation signal maybe for example, a plurality of pulse code modulated samples representing sound. The dynamic range reduction circuit modifies a selected signal to reduce the dynamic range of the sound reproduced based on the modulation signal. The selected signal is either the modulation signal or a reference signal. In one embodiment, the dynamic range reduction circuit modifies the selected signal by processing the selected signal based on a smooth saturating function. In another embodiment, the dynamic range reduction circuit modifies the amplitude of the reference signal based on an envelope size of the modulation signal.

Apparatus for reproducing sound with a reduced dynamic range

A low power consumption oscillator circuit. The oscillator circuit comprises a capacitor coupled to a first resistor that is capable of delaying discharge of the capacitor. The oscillator circuit further comprises a first inverter coupled to the capacitor and having a first input. The first inverter is capable of applying charge to the capacitor when a first voltage potential on the first input is above a first threshold voltage of the first inverter. The first inverter is capable of removing charge from the capacitor when a second voltage potential on the first input is below a second threshold voltage of the first inverter. The oscillator circuit further comprises threshold detection circuitry having a second circuitry is coupled to the first input of the first inverter, and the second input is coupled to the capacitor. The threshold detection circuitry is capable of applying the first voltage potential on the first input when a third voltage potential on the second input is below a third threshold voltage of the threshold detection circuitry. The threshold detection circuitry is capable of applying the second voltage potential on the first input when a fourth voltage potential on the second input is above the third threshold voltage of the threshold detection circuitry. The third threshold voltage of the threshold detection circuitry is different than the first and second threshold voltages.

Low power consumption oscillator circuit

A technique is provided for substantially reducing clicks and pops caused by power cycling, in particular, the power cycling conservation strategy used in a portable computer. More specifically, an audio amplifier arrangement for a computer, in accordance with one embodiment of the present invention, includes a differential amplifier having a first input terminal, a second input terminal and an output terminal. A sound output connector may be connected to the output terminal through a signal path. First switching circuitry is responsive to a first mute signal for connecting together the first input terminal and the second input terminal through a low-impedance path. As a result, an output signal produced by the differential amplifier is essentially forced to zero. When power is removed from or applied to the differential amplifier, however, its behavior is not entirely predictable, and the output signal produced cannot be guaranteed to remain zero throughout the power-down transition. Therefore, further in accordance with the invention, second switching circuitry is responsive to a second mute signal for substantially interrupting the signal path by switching a high impedance into the signal path. In a preferred embodiment, the first switching circuitry and the second circuitry are realized by MOSFETs which in cascade yield approximately 120 dB of attenuation, inaudible to a user by any standard.

Muting of computer sound system during power cycling

An open-loop speaker amplifier and a dynamic range reduction circuit are disclosed. The speaker amplifier includes a bridge driver and a bridge circuit. The bridge circuit includes a first set of switches and a second set of switches. When the first set of switches are activated, a positive current flows through a speaker load. When the second set of switches are activated, a negative current flows through the speaker load. The bridge driver generates a pulse width modulated signal and a delayed pulse width modulated signal to drive the first and second set of switches of the bridge circuit responsive to a modulation signal. The modulation signal may be, for example, a plurality of pulse code modulated samples representing sound. The dynamic range reduction circuit modifies a selected signal to reduce the dynamic range of the sound reproduced based on the modulation signal. The selected signal is either the modulation signal or a reference signal. In one embodiment, the dynamic range reduction circuit modifies the selected signal by processing the selected signal based on a smooth saturating function. In another embodiment, the dynamic range reduction circuit modifies the amplitude of the reference signal based on an envelope size of the modulation signal.

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San Jose, CA, United States of America

Steven E Austin