Circuit Having a Low Power Mode

A portable audio player including an integrated circuit (IC) capable of responding to power-up messages while in a low-power state, the IC comprising:

• a digital interface;
• a digital input connected to the digital interface;
• primary operation circuitry configured to perform one or more primary tasks and connected to the digital interface, the IC being configured to selectively remove substantially all power from the primary operation circuitry;
• and
• thin power circuitry connected to the primary operation circuitry and the digital input and configured to
• while power is removed from the primary operation circuitry, receive a set of one or more predefined digital signals over the digital input, and
• in response to the set of predefined digital signals, power up the primary operation circuitry.

A mobile telephone including an integrated circuit (IC) capable of responding to power-up messages while in a low-power state, the IC comprising:

• a digital interface;
• a digital input connected to the digital interface;
• primary operation circuitry configured to perform one or more primary tasks and connected to the digital interface, the IC being configured to selectively remove substantially all power from the primary operation circuitry;
• and
• thin power circuitry connected to the primary operation circuitry and the digital input and configured to
• while power is removed from the primary operation circuitry, receive a set of one or more predefined digital signals over the digital input, and
• in response to the set of predefined digital signals, power up the primary operation circuitry.

A method for operating an integrated circuit (IC) including primary operation circuitry and thin power circuitry, the method comprising:

• powering down the primary operation circuitry while keeping the thin power circuitry powered;
• receiving a set of one or more predefined digital signals over a digital input by the power manager circuitry;
• and
• in response to the set of predefined digital signals, powering up the primary operation circuitry by the thin power circuitry.

An integrated circuit (IC) capable of reconfiguration while in a low-power state, the IC comprising:

• a configuration memory configured to store configuration information for the IC;
• a digital interface;
• a digital input connected to the digital interface;
• primary operation circuitry configured to perform one or more primary tasks and connected to the digital interface, the IC being configured to selectively remove substantially all power from the primary operation circuitry;
• and
• thin power circuitry connected to the primary operation circuitry, the digital input and the configuration memory and configured to
• while power is removed from the primary operation circuitry, receive a set of one or more predefined digital signals over the digital input, and
• in response to the set of predefined digital signals, change the information stored in the configuration memory,
• wherein changing the information stored in the configuration memory results in a change of the configuration of the IC.

An integrated circuit (IC) capable of communication with external devices while in a low-power state, the IC comprising:

• an external device interface connected to one or more external devices;
• a host interface connected to a host;
• primary operation circuitry configured to perform one or more primary tasks and connected to the external device interface and the host interface, the IC being configured to selectively remove substantially all power from the primary operation circuitry;
• and
• thin power circuitry connected to the primary operation circuitry, and the external device and host interfaces and configured to
• while power is removed from the primary operation circuitry, receive a set of one or more predefined digital signals over the external device interface, and
• in response to the set of predefined digital signals, send a signal to the host over the host interface.

An integrated circuit (IC) capable of responding to power-up messages while in a low-power state, the IC comprising:

• a digital interface;
• a digital input connected to the digital interface;
• primary operation circuitry connected to the digital interface and configured to perform one or more primary tasks, during a normal power mode of operation of the IC, and to seize operation during a low power mode of operation of the IC, the primary operation circuitry including at least one primary power on reset cell, configured to initialize the primary operation circuitry during a power up of the primary operation circuitry;
• and
• thin power circuitry connected to the primary operation circuitry and the digital input, the thin power circuitry configured to operate during the normal and low power modes of the IC, the thin power circuitry including at least one thin power on reset cell configured to initialize the thin power circuitry during a power up of the thin power circuitry, the thin power on reset cell being distinct from the primary power on reset cell.