Multi-functional pin of an integrated circuit

1. An integrated circuit comprising:

a first pin;

a second pin;

a latch;

a switchable resistive element coupled between the first pin and the second pin, the switchable resistive element having a control input, and the switchable resistive element configured to have a pull down resistance state or a high resistance state responsive to the control input;

a comparator having a comparator input, a reference input and a comparator output, the comparator input coupled to the first pin; and

a logic circuit having a logic input, a power good input and a control output, the logic input coupled through the latch to the comparator output, and the control output coupled to the control input;

the first pin configured to have a first voltage during the pull down resistance state, a second voltage during the pull down resistance state, and a third voltage during the high resistance state, in which the third voltage is larger than the second voltage, and a voltage at the reference input is between the first and second voltages.

2. The integrated circuit of claim 1 , wherein the switchable resistive element comprises a pull down resistor connected in series with a switch, in which the control input is part of the switch, the switch is configured to close in the pull down resistance state, and the switch is configured to open in the high resistance state.

3. The integrated circuit of claim 1 , wherein the switchable resistive element is a controllable resistor.

4. The integrated circuit of claim 3 , wherein the controllable resistor is a transistor.

5. The integrated circuit of claim 1 , wherein the switchable resistive element is configured to be a pull down path responsive to a power good signal indicating that a power supply is outside an operating range.

6. The integrated circuit of claim 1 , wherein the switchable resistive element is configured to decouple the first pin from the second pin responsive to a power good signal indicating that a power supply is within an operating range.

7. The integrated circuit of claim 1 , further comprising a power good monitor coupled to the first pin, the power good monitor configured to determine that a power supply is either: within an operating range, responsive to a power good signal; or outside the operating range, responsive to an enable signal that has a lower voltage level than the power good signal.

8. The integrated circuit of claim 7 , wherein a voltage of the enable signal has a range of a logic low state for the power good, and a voltage of the power good signal has a range of a logic high state for the power good monitor.

9. The integrated circuit of claim 1 , wherein the second pin is coupled to a reference or to a ground.

10. The integrated circuit of claim 1 , further comprising an integer number of pins including the first pin and the second pin, in which the integer number is at least three and less than seven.

11. The integrated circuit of claim 1 , further comprising a voltage divider that comprises: the switchable resistive element; and a second resistive element internal or external to the integrated circuit.

12. A system comprising:

an integrated circuit comprising:

a first pin;

a second pin;

a latch;

a switchable resistive element coupled between the first pin and the second pin, the switchable resistive element having a control input, and the switchable resistive element configured to have a pull down resistance state or a high resistance state responsive to the control input;

a comparator having a comparator input, a reference input and a comparator output, the comparator input coupled to the first pin; and

a logic circuit having a logic input, a power good input and a control output, the logic input coupled through the latch to the comparator output, and the control output coupled to the control input;

a supply voltage input;

a second resistive element coupled between the supply voltage input and the first pin; and

a control circuit having an enable input and an enable output, the enable input coupled to the first pin, and the control circuit comprising a control element configured to control an enable signal at the enable output responsive to the enable input;

the first pin configured to have a first voltage during the pull down resistance state, a second voltage during the pull down resistance state, and a third voltage during the high resistance state, in which the third voltage is larger than the second voltage, and a voltage at the reference input is between the first and second voltages.

13. The system of claim 12 , wherein the control element is configured to control the enable signal by selectively coupling the first pin to a reference or to a ground, responsive to the enable input.

14. The system of claim 12 , wherein the control circuit comprises a monitor circuit coupled to the first pin, the monitor circuit configured to monitor a power good signal that has the third voltage.

15. An integrated circuit comprising:

a first pin;

a second pin;

a switchable path coupled between the first pin and the second pin, the switchable path having a control input, and the switchable path configured to: couple the first pin to the second pin, or decouple the first pin from the second pin, responsive to the control input;

a comparator having a comparator input, a reference input and a comparator output, the comparator input coupled to the first pin;

a latch having a latch input and a latch output, the latch input coupled to the comparator output; and

a logic circuit having a logic input, a power good input and a control output, the logic input coupled to the latch output, and the control output coupled to the control input, in which the control output is responsive to the power good input.

16. The integrated circuit of claim 15 , wherein the switchable path includes a pull down resistor and a switch coupled in series, and the control input is part of the switch.