Over-voltage tolerant power supply sensing circuit with programmable trip-point

Abstract

A power sensing circuit in a first voltage domain senses an input voltage from a second voltage domain and provides a power OK signal. The maximum supply voltage of the first voltage domain is above a maximum tolerance for devices in the first voltage domain. Accordingly, protection techniques are employed to ensure that the potential difference between any two terminals of devices in the power sensing circuit does not exceed the maximum tolerance limit. The protection techniques utilize reference voltage-based techniques including level shifting and use of protection devices in transistor stacks. An over-voltage tolerant Schmitt trigger circuit is also employed in the power sensing circuit. A trip point device on the input of the power sensing circuit utilizes a programmable bias voltage to adjust the trip point of the power sensing circuit to accommodate different maximum input voltages from the second voltage domain.