Power supply controller

Abstract

A power supply controller including a MOSFET between a power source and a load, a ground terminal, a gate driving circuit structured to control a gate potential of the MOSFET to turn on power and control the gate potential of the MOSFET to turn off power based on a ground terminal potential, and a turn-off circuit structured to switch the MOSFET into a turn-off state regardless of control by the gate driving circuit when the ground terminal potential is at a higher value than a source potential of the MOSFET.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Illustrative aspects in accordance with the invention will be described in detail with reference to the following figures wherein:

FIG. 1 is a block diagram showing an overview of a power supply controller according to an illustrative aspect of the present invention;

FIG. 2 is a timing chart showing an operation of a discharge preventing circuit responsive to variations in the level of a power supply voltage; and

FIG. 3 is a block diagram showing a variation of the illustrative aspect.

Claims

1. A power supply controller comprising: an n-channel MOSFET provided between a power source and a load;a ground terminal;a gate driving circuit structured to control a gate terminal potential of the MOSFET to turn on power and control the gate terminal potential of the MOSFET to turn off power based on a ground terminal potential; anda turn-off circuit structured to switch the MOSFET into a turn-off state regardless of control by the gate driving circuit when the ground terminal potential is at a higher value than a source potential of the MOSFET.

2. The power supply controller according to claim 1, wherein the higher value is set to a value greater than the potential difference between the ground terminal and a source terminal of the MOSFET when the ground terminal is properly grounded and the MOSFET is turned off based on the gate driving circuit.

3. The power supply controller according to claim 1, wherein the higher value is set to a value smaller than a threshold voltage of the MOSFET.

4. The power supply controller according to claim 2, wherein the higher value is set to a value smaller than a threshold voltage of the MOSFET.

5. The power supply controller according to claim 1, wherein the turn-off circuit has a switching element connected between a gate terminal and a source terminal of the MOSFET and turns on the switching element to reduce the voltage between the gate and source terminal to a value below a threshold voltage of the MOSFET when the ground terminal potential is at the higher value than the source potential of the MOSFET.

6. The power supply controller according to claim 2, wherein the turn-off circuit has a switching element connected between a gate terminal and the source terminal of the MOSFET, wherein the turn-off circuit turns on the switching element to reduce the voltage between the gate and source terminal to a value below a threshold voltage of the MOSFET when the ground terminal potential is at the higher value than the source potential of the MOSFET.

7. The power supply controller according to claim 3, wherein the turn-off circuit has a switching element connected between a gate and source terminal of the MOSFET, wherein the turn-off circuit turns on the switching element to reduce the voltage between the gate and source terminal to a value below the threshold voltage of the MOSFET when the ground terminal potential is at the higher value than the source potential of the MOSFET.

8. The power supply controller according to claim 4, wherein the turn-off circuit has a switching element connected between a gate and source terminal of the MOSFET, wherein the turn-off circuit turns on the switching element to reduce the voltage between the gate and source terminal to a value below the threshold voltage of the MOSFET when the ground terminal potential is at the higher value than the source potential of the MOSFET.

9. A power supply controller comprising: an MOSFET provided between a power source and a load, wherein the MOSFET further includes a gate terminal and a source terminal;a ground terminal;a gate driving circuit structured to control a gate terminal potential to turn on power and control the gate terminal potential to turn off power based on a ground terminal potential; anda turn-off circuit capable of overriding the gate driving circuit to switch the MOSFET into a turn-off state when the ground terminal potential meets a set value, further wherein the set value is at a higher value than the source potential of the MOSFET.

10. The power supply controller according to claim 9, wherein the set value is greater than the potential difference between the ground terminal and a source terminal of the MOSFET when the ground terminal is properly grounded and the MOSFET is turned off based on the gate driving circuit.

11. The power supply controller according to claim 9, wherein the set value is smaller than a threshold voltage of the MOSFET.

12. The power supply controller according to claim 9, wherein the turn-off circuit includes a switching element connected between the gate terminal and the source terminal of the MOSFET.

13. The power supply controller according to claim 12, wherein the turn-off circuit turns on the switching element to reduce the voltage between the gate and source terminal to a value below a threshold voltage of the MOSFET when the ground terminal potential is at the higher value than the source terminal potential of the MOSFET.

14. A power supply controller comprising: an MOSFET provided between a power source and a load, wherein the MOSFET further includes a gate terminal and a source terminal;a ground terminal;a gate driving circuit means for controlling a gate terminal potential of the MOSFET to turn on power and controlling a gate terminal potential of the MOSFET to turn off based on a ground terminal potential; anda turn-off circuit means for overriding the gate driving circuit to switch the MOSFET into a turn-off state when the ground terminal potential meets a set value, further wherein the set value is at a higher value than a source terminal potential of the MOSFET.

15. The power supply controller according to claim 14, wherein the set value is greater than the potential difference between the ground terminal and a source terminal of the MOSFET when the ground terminal is properly grounded and the MOSFET is turned off based on the gate driving circuit.

16. The power supply controller according to claim 14, wherein the set value is smaller than a threshold voltage of the MOSFET.

17. The power supply controller according to claim 14, wherein the turn-off circuit means includes a switching element connected between the gate terminal and the source terminal of the MOSFET.

18. The power supply controller according to claim 17, wherein the turn-off circuit means turns on the switching element to reduce the voltage between the gate and source terminal to a value below a threshold voltage of the MOSFET when the ground terminal potential is at the higher value than the source terminal potential of the MOSFET.