Abstract: In various embodiments, rail decoupling circuits that are powered by an always on voltage rail allow a core voltage rail to power up independently of an I/O voltage rail without jeopardizing I/O pad circuits that are powered by the I/O voltage rail. In an embodiment, when the always on voltage rail is powered-up and a chip reset signal is asserted, the rail decoupling circuits drive control inputs of the I/O pad circuits based on default values. When the chip reset signal is de-asserted, the rail decoupling circuits drive the control inputs of the I/O pad circuits based on signals received from circuits powered by the core voltage rail. Because the rail decoupling circuits maintain control of the I/O pad circuits until the chip-reset is de-asserted, the core voltage rail can power up at any time before the chip-reset signal is de-asserted irrespective of when the I/O voltage rail powers up.

Abstract: In various embodiments, rail decoupling circuits that are powered by an always on voltage rail allow a core voltage rail to power up independently of an I/O voltage rail without jeopardizing I/O pad circuits that are powered by the I/O voltage rail. In an embodiment, when the always on voltage rail is powered-up and a chip reset signal is asserted, the rail decoupling circuits drive control inputs of the I/O pad circuits based on default values. When the chip reset signal is de-asserted, the rail decoupling circuits drive the control inputs of the I/O pad circuits based on signals received from circuits powered by the core voltage rail. Because the rail decoupling circuits maintain control of the I/O pad circuits until the chip-reset is de-asserted, the core voltage rail can power up at any time before the chip-reset signal is de-asserted irrespective of when the I/O voltage rail powers up.

Abstract: An integrated circuit (IC) based detection circuit for determining a strap value and a method of detecting a digital strap value. In one embodiment, the detection circuit includes: (1) a first receiver including transistors having first electrical characteristics that define a first threshold for the first receiver, the first receiver operable to generate a first binary digit based on an input signal and the first threshold and (2) a second receiver including transistors having second electrical characteristics that differ from the first electrical characteristics and define a second threshold for the second receiver that is lower than the first threshold, the second receiver operable to generate a second binary digit based on the input signal and the second threshold, the first and second binary digits indicating whether the strap value lies above the first threshold, between the first and second thresholds or below the second threshold.