Methods, apparatus, and systems are disclosed for voltage supervisors. An example apparatus includes a first switch having a first source, a first drain, and a first gate, a first resistor having a first terminal and a second terminal, the first terminal coupled to the first source and second terminal coupled to the first drain, a second resistor having a third terminal and a fourth terminal, the third terminal coupled to the second terminal, a third resistor having a fifth terminal and a sixth terminal, the fifth terminal coupled to the fourth terminal, a fourth resistor having a seventh terminal and an eighth terminal, the seventh terminal coupled to the sixth terminal, a second switch having a second source, a second drain, and a second gate, the second source coupled to the seventh terminal, and a comparator having an output, the output coupled to the first gate and the second gate.