Management of power domains in an integrated circuit

A method of operating a circuit, the method comprising:

• operating in a first mode, wherein in the first mode, a first power domain operates in an active power mode and a second power domain operates in an active power mode, wherein in the first mode, a first set of at least one terminal of a first circuit of the first power domain are coupled to a second set of at least one terminal of a second circuit of a second power mode via an isolation circuit for providing signals from the first circuit to the second circuit;
• and
• operating in a second mode, wherein in the second mode, the first power domain operates in a power gated mode and a second power domain operates in an active power mode, wherein in the second mode, the second set of at least one terminal is coupled to a third set of at least one terminal via the isolation circuit, wherein the first set of at least one terminal is not coupled to the second set of at least one terminal via the isolation circuit,
• wherein when operating in the first mode, the third set of at least one terminal is not coupled to the second set of at least one terminal via the isolation circuit, and
• wherein when operating in the second mode, the third set of at least one terminal provides via the isolation circuit to the second set of at least one terminal a first value at a first time and a second value at a second time.

A method of operating a circuit, the method comprising:

• operating in a first mode, wherein in the first mode, a first power domain of the circuit operates in an active power mode and a second power domain of the circuit operates in an active power mode, wherein in the first mode, a first set of at least one terminal of a first circuit of the first power domain are coupled to a second set of at least one terminal of a second circuit of the second power domain via an isolation circuit for providing signal values from the first circuit to the second circuit;
• transitioning from the first mode to a second mode, wherein the transitioning includes placing the isolation circuit in a mode to couple a third set of at least one terminal to the second set of at least one terminal and to decouple the first set of at least one terminal from the second set of at least one terminal and then placing the first power domain in a gated power mode;
• operating in the second mode, wherein in the second mode, the first power domain operates in the gated power mode and a second power domain operates in an active power mode, wherein in the second mode, the second set of at least one terminal is coupled to the third set of at least one terminal via the isolation circuit, wherein the first set of at least one terminal is not coupled to the second set of at least one terminal via the isolation circuit;
• wherein when operating in the first mode, the third set of at least one terminal is not coupled to the second set of at least one terminal via the isolation circuit;
• wherein when operating in the second mode, providing by the third set of at least one terminal via the isolation circuit to the second set of at least one terminal a first value at a first time and a second value at a second time;
• transitioning from the second mode to the first mode, wherein the transitioning includes placing the first power domain in an active mode and then placing the isolation circuit in a mode to couple the first set of at least one terminal to the second set of at least one terminal and to decouple the third set of at least one terminal from the second set of at least one terminal.