Power switching device and control method thereof

Patent metadata

Field	Value
Publication number	US-10700509-B2
Application number	US-201715830022-A
Country	US
Kind code	B2
Filing date	Dec 4, 2017
Priority date	Dec 30, 2016
Publication date	Jun 30, 2020
Grant date	Jun 30, 2020

Abstract

A power switching device is provided. A first transmitting switch transmits an input voltage to an output node when the first transmitting switch is turned on. When the current passing through the first transmitting switch exceeds a predetermined value, a current limiting circuit turns off the first transmitting switch. When a short circuit occurs between the output node and a ground node, a short protection circuit turns off the first transmitting switch. The short protection circuit includes a first comparator and a first set circuit. The first comparator compares a voltage of the output node and a first reference voltage to generate a first comparison result to turn off the first transmitting switch. The first set circuit generates the first reference voltage according to the voltage of the output node. The first reference voltage is less than the voltage of the output node.

First claim

What is claimed is:

1. A power switching device, comprising:
a first transmitting switch, wherein the first transmitting switch transmits an input voltage to an output node when the first transmitting switch is turned on;
a current limiting circuit coupled to the first transmitting switch to detect a current passing through the first transmitting switch, wherein when the current is higher than a predetermined value, the current limiting circuit turns off the first transmitting switch; and
a short protection circuit coupled to the first transmitting switch, wherein when a short circuit occurs between the output node and a ground node, the short protection circuit turns off the first transmitting switch, wherein the short protection circuit comprises:
a first comparator comparing a voltage of the output node and a first reference voltage to generate a first comparison result to turn off the first transmitting switch; and
a first set circuit receiving the voltage of the output node and generating the first reference voltage according to the voltage of the output node, wherein the first reference voltage is less than the voltage of the output node,
wherein the first set circuit is a delay circuit, and the delay circuit decreases the voltage of the output node to generate the first reference voltage.

2. The power switching device as claimed in claim 1 , wherein the first set circuit comprises:
a resistor coupled between the output node and the first comparator; and
a capacitor coupled between the first comparator and the resistor and coupled to the ground node.

3. The power switching device as claimed in claim 1 , wherein the short protection circuit further comprises:
a transistor turning off the first transmitting switch according to the first comparison result.

4. The power switching device as claimed in claim 3 , wherein when the transistor is turned on, the first transmitting switch is turned off.

5. The power switching device as claimed in claim 4 , wherein when the short circuit occurs between the output node and the ground node, the first comparator turns on the transistor such that the transistor transmits a ground voltage to the first transmitting switch to turn off the first transmitting switch.

6. The power switching device as claimed in claim 1 , wherein when the current is less than the predetermined value, the current limiting circuit turns on the first transmitting switch.

7. The power switching device as claimed in claim 1 , further comprising:
a second transmitting switch, wherein when the second transmitting switch is turned on, the second transmitting switch transmits the input voltage to the output node,
wherein when the current is less than the predetermined value, the current limiting circuit turns on the second transmitting switch, and
wherein when the short circuit occurs between the output node and the ground node, the second transmitting switch is turned on.

8. The power switching device as claimed in claim 1 , wherein the current limiting circuit comprises:
a sensing element coupled to the first transmitting switch in series and detecting the current passing through the first transmitting switch to generate a sensed signal; and
a second comparator comparing the sensed signal and a second reference voltage to generate a second comparison result and turning on or off the first transmitting switch according to the second comparison result.

9. The power switching device as claimed in claim 8 , wherein the current limiting circuit further comprises:
a second set circuit receiving the input voltage to generate the second reference voltage according to the input voltage.

10. A control method for a power switching device comprising a first transmitting switch, wherein when the first transmitting switch is turned on, the first transmitting switch transmits an input voltage to an output node, comprising:
detecting a current passing through the first transmitting switch;
turning off the first transmitting switch when the current is higher than a first predetermined value, and turning on the first transmitting switch when the current is less than the first predetermined value;
detecting a voltage of the output node; and
turning off the first transmitting switch when the voltage of the output node is less than a second predetermined value.

11. The control method as claimed in claim 10 , further comprising:
turning on or off the first transmitting switch when the voltage of the output node is higher than the second predetermined value.

12. The control method as claimed in claim 10 , further comprising:
decreasing the input voltage to generate the first predetermined value.

13. The control method as claimed in claim 10 , further comprising:
decreasing the voltage of the output node to generate the second predetermined value.

14. The control method as claimed in claim 10 , further comprising:
turning off a second transmitting switch when the voltage of the output node is less than the second predetermined value, wherein the second transmitting switch is coupled to the first transmitting switch in parallel.

15. The control method as claimed in claim 14 , further comprising:
turning off the second transmitting switch when the current is higher than the first predetermined value; and
turning on the second transmitting switch when the current is less than the first predetermined value.

16. The control method as claimed in claim 14 , further comprising:
turning on a third transmitting switch when the voltage of the output node is less than the second predetermined value, wherein the third transmitting switch is coupled to the first transmitting switch in parallel, and when the third transmitting switch is turned on, the third transmitting switch transmits the input voltage to the output node.

17. The control method as claimed in claim 16 , further comprising:
turning off the third transmitting switch when the current is higher than the first predetermined value; and

turning on the third transmitting switch when the current is less than the first predetermined value.

Assignees

• Nuvoton Technology Corp

Inventors

• Li Cheng-Tao

Classifications

• H02H3/105 Primary

  responsive to excess current and fault current to earth · CPC title

• H02H3/087 Primary

  for DC applications · CPC title

• H02H11/006 Primary

  in case of too high or too low voltage · CPC title