DRIVING CIRCUIT

• US 20170237422A1
• Filed: 04/28/2017
• Published: 08/17/2017
• Est. Priority Date: 05/15/2015
• Status: Active Grant

• Current Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Original Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Inventors: AKAHANE, Masashi
• Granted Patent: US 10,511,298 B2
• Time in Patent Office: Days
• CPC Class Codes: H03K 17/08122 in field-effect transistor switches
• CPC Class Codes: H03K 17/163 Soft switching
• CPC Class Codes: H03K 17/18 Modifications for indicating state of switch
• CPC Class Codes: H03K 17/223 in field-effect transistor switches
• CPC Class Codes: H03K 19/018507 Interface arrangements
• CPC Class Codes: H03K 2017/0806 against excessive temperature
• CPC Class Codes: H03K 3/033 Monostable circuits
• CPC Class Codes: H03K 3/037 Bistable circuits
• CPC Class Codes: H03K 5/1252 Suppression or limitation of noise or interference specially adapted for transmission systems H04B15/00, H04L25/08

Abstract

Voltage surge is prevented when the output from a driver of a driving circuit performs a hard shutdown. In this manner, the elements in the driving circuit are prevented from being damaged by the voltage surge. A driving circuit includes a level shift circuit configured to convert an input signal from a preceding-stage circuit into an output signal having a higher voltage than the input signal, and a controller configured to determine whether a switch element is to perform a soft shutdown based on a state signal indicating a state of the preceding-stage circuit. Here, the driving circuit is configured to drive the switch element.

Claims

1. A driving circuit comprising:

a level shift circuit configured to convert an input signal from a preceding-stage circuit into a signal having a higher voltage than the input signal; and

a controller configured to output a signal to allow a first switch element to perform a soft shutdown based on an output signal from the level shift circuit, wherein

the driving circuit is configured to drive the first switch element.

2. The driving circuit as set forth in claim 1, wherein

the preceding-stage circuit includes an abnormality detecting circuit, and

the controller determines whether the first switch element is to perform a soft shutdown based on an output signal from the abnormality detecting circuit.

3. The driving circuit as set forth in claim 2, wherein

the first switch element is switched on or off according to a control signal input thereinto,

the driving circuit further comprises a latch circuit configured to generate the control signal according to a set signal and a reset signal that are input from the preceding-stage circuit to the level shift circuit, and

the controller determines whether the first switch element is to perform a soft shutdown based on an output from the latch circuit and a state signal generated based on the output signal from the abnormality detecting circuit.

4. The driving circuit as set forth in claim 3, wherein

the controller allows the first switch element to perform a soft shutdown when the output signal from the latch circuit indicates that the first switch element is to be switched on and the state signal indicates that abnormality is detected in the preceding-stage circuit.

5. The driving circuit as set forth in claim 3, wherein

the set signal indicates a predetermined logical value when the first switch element is to be switched on,

the reset signal indicates a predetermined logical value when the first switch element is to perform a hard shutdown,

the state signal indicates a predetermined logical value when abnormality is detected in the preceding-stage circuit, and

the driving circuit further comprises an anti-error circuit configured to, except when the first switch element performs a soft shutdown, maintain the first switch element switched on or off when two or more of the set signal, the reset signal and the state signal indicate the predetermined logical values.

6. The driving circuit as set forth in claim 3, wherein

the level shift circuit includes a state signal input circuit configured to shift a level of the state signal, a set signal input circuit configured to shift a level of the set signal and a reset signal input circuit configured to shift a level of the reset signal,

the state signal input circuit, the set signal input circuit and the reset signal input circuit each include a resistance element connected to a high-potential side of the driving circuit and a transistor having a drain connected to a low-potential side of the resistance element,

in the state signal input circuit, the set signal input circuit and the reset signal input circuit,

high-potential sides of the resistance elements are connected to each other and

the resistance elements have a same resistance value and the transistors have a same characteristic.

7. The driving circuit as set forth in claim 2, wherein

the preceding-stage circuit determines whether the first switch element is to perform a soft shutdown based on a signal input from outside and designed to control the first switch element and the output signal from the abnormality detecting circuit.

8. The driving circuit as set forth in claim 7, wherein

the preceding-stage circuit outputs to the level shift circuit a state signal designed to allow the first switch element to perform a soft shutdown when the signal input from outside and designed to control the first switch element indicates that the first switch element is to be switched on and the output signal from the abnormality detecting circuit indicates that abnormality is detected.

9. The driving circuit as set forth in claim 1, wherein

the controller controls the first switch element to start a hard shutdown after a predetermined period of time has elapsed after the first switch element starts a soft shutdown.

10. The driving circuit as set forth in claim 9, wherein

the controller determines the predetermined period of time depending on a type of an abnormality detected in the preceding-stage circuit.

11. The driving circuit as set forth in claim 9, wherein

the controller determines a time constant of a soft shutdown depending on a type of an abnormality detected in the preceding-stage circuit.

12. The driving circuit as set forth in claim 2, wherein

the preceding-stage circuit includes a low-side control circuit configured to switch on or off a second switch element that is connected in series with a low-potential side of the first switch element, wherein

the abnormality detecting circuit includes a circuit configured to detect a state of the second switch element.