Systems and methods for measuring power system current using OR-ing MOSFETs

1. A power supply unit comprising:

an output stage configured to generate a direct-current output voltage;

a power supply output;

an OR-ing stage comprising:

a metal-oxide-semiconductor field effect transistor (MOSFET), including a source terminal connected to the output stage and a drain terminal connected to the power supply output, for preventing a reverse current flow from the output to the output stage; and

a diode including an anode cathode connected to the drain terminal and an anode connected to a MOSFET terminal selected from: the source terminal and a sense terminal;

a controller configured to:

measure a signal indicative of a voltage associated with the OR-ing MOSFET; and

determine an estimated output current of the power supply based on the signal.

2. The power supply unit of claim 1 , wherein the signal is indicative of a drain-to-source voltage of the MOSFET.

3. The power supply unit of claim 1 , wherein the MOSFET comprises a current-sensing power MOSFET and the signal is indicative of a current associated with a sense terminal of the current-sensing power MOSFET.

4. The power supply unit of claim 1 , wherein the MOSFET comprises an n-type MOSFET.

5. The power supply unit of claim 1 , wherein the controller is further configured to calibrate a drain-to-source resistance of the MOSFET.

6. The power supply of claim 5 , wherein the controller is configured to calibrate the drain-to-source resistance of the MOSFET by comparing a current measurement measured by automatic test equipment coupled to the output to the estimated output current of the power supply based on the signal.

7. The power supply of claim 5 , wherein the controller is configured to calibrate the drain-to-source resistance of the MOSFET by comparing a current measurement associated with a current transformer of the one or more stages to the estimated output current of the power supply based on the signal.

8. The power supply of claim 1 , wherein the controller is configured to perform compensation to account for temperature variation of a drain-to-source resistance of the MOSFET based on an temperature associated with the MOSFET.

9. The power supply of claim 8 , wherein the ambient temperature is sensed by a negative temperature coefficient resistor of the power supply.

10. A method comprising:

generating, in a power supply, a sense signal indicative of a voltage associated with a metal-oxide-semiconductor field effect transistor (MOSFET) of a sensing stage coupled between a power supply output and an output stage configured to generate a direct-current output voltage, wherein a source terminal of the MOSFET is connected to the output stage and a drain terminal of the MOSFET is connected to the power supply output;

amplifying the sense signal with an operational amplifier circuit to produce an amplified signal; and

determining an estimated output current of the power supply based on the amplified signal.

11. The method of claim 10 , wherein the sense signal is indicative of a drain-to-source voltage of the MOSFET.

12. The method of claim 10 , wherein the MOSFET comprises a current-sensing power MOSFET and the sense signal is indicative of a current associated with a sense terminal of the current-sensing power MOSFET.

13. The method of claim 10 , wherein the MOSFET comprises an n-type MOSFET and wherein a cathode of a diode is connected to the drain terminal and an anode of the diode is connected to a MOSFET terminal selected from the source terminal and a sense terminal.

14. The method of claim 10 , further comprising calibrating a drain-to-source resistance of the MOSFET.

15. The method of claim 14 , wherein calibrating the drain-to-source resistance comprises comparing a current measurement measured by automatic test equipment coupled to the power supply output to the estimated output current of the power supply based on the amplified signal.

16. The method of claim 14 , wherein calibrating the drain-to-source resistance comprises comparing a current measurement associated with a current transformer of the power supply to the estimated output current of the power supply based on the amplified signal.

17. The method of claim 10 , further comprising performing compensation to account for temperature variation of a drain-to-source resistance of the MOSFET based on an temperature associated with the MOSFET.

18. The method of claim 17 , wherein the ambient temperature is sensed by a negative temperature coefficient resistor of the power supply.

19. An information handling system comprising:

a power supply unit comprising:

an output stage configured to generate a direct-current output voltage;

a power supply output;

an OR-ing metal-oxide-semiconductor field effect transistor (MOSFET) including a source terminal connected to the output stage and a drain terminal connected to the power supply output for preventing a reverse current flow from the output to the output stage;

an operational amplifier configured to:

receive a sense signal indicative of a voltage associated with the OR-ing MOSFET; and

produce an amplified signal in accordance with the sense signal; and

a controller configured to:

receive the amplified signal; and

determine an estimated output current of the power supply based on the amplified signal; and

at least one information handling resource electrically coupled to the power supply unit.

20. The power supply unit of claim 19 , wherein the sense signal is indicative of one of:

a drain-to-source voltage of the MOSFET; and

a current associated with a sense terminal of a current-sensing power MOSFET integral to the MOSFET.