Power safety circuit, integrated circuit device and safety critical system

Patent metadata

Field	Value
Publication number	US-9620992-B2
Application number	US-201114354278-A
Country	US
Kind code	B2
Filing date	Oct 27, 2011
Priority date	Oct 27, 2011
Publication date	Apr 11, 2017
Grant date	Apr 11, 2017

Abstract

A power safety circuit comprises a power sense terminal; an output terminal; an output driver unit connected to the output terminal; an input terminal connectable to receive a first power from a power source and arranged to supply the first power to the output driver unit; and a power detection unit arranged to detect a state of the input terminal and provide a power sense signal to the power sense terminal; wherein the power sense terminal is arranged to supply a second power to the output driver unit when the power sense signal indicates a level of the first power below a minimum level for driving the output terminal. An integrated circuit device comprises at least one power safety circuit. A safety critical system comprises at least one integrated circuit device with at least one power safety circuit.

First claim

The invention claimed is:

1. A power safety circuit, comprising
a power sense terminal;
an output terminal;
an output driver unit connected to said output terminal;
an input terminal connectable to receive a first power from a power source and arranged to supply said first power to said output driver unit; and
a power detection unit arranged to detect a state of said input terminal and provide a power sense signal to said power sense terminal, wherein said power sense terminal is arranged to supply a second power to said output driver unit when said power sense signal indicates that a level of said first power is below a minimum level for driving said output terminal, and wherein a level of said second power is lower than said level of said first power.

2. The power safety circuit as claimed in claim 1 , wherein said level of said first power being below said minimum level corresponds to an absence of said first power.

3. The power safety circuit as claimed in claim 1 , wherein said output terminal is a fail safe terminal.

4. The power safety circuit as claimed in claim 1 , wherein said output driver unit is arranged to drive said output terminal in a fail safe state when receiving said second power.

5. The power safety circuit as claimed in claim 1 , wherein said power detection unit comprises a power-on reset detection circuit.

6. The power safety circuit as claimed in claim 1 , wherein said output driver unit comprises a dedicated low power circuit arranged to drive said output terminal when receiving said second power from said power sense terminal.

7. The power safety circuit as claimed in claim 1 , wherein said power detection unit is arranged to control a provision of said second power by said power sense terminal.

8. The power safety circuit as claimed in claim 1 , wherein said output terminal is connected to a control unit arranged to switch a safety critical system into a safety mode depending on said state of said input terminal.

9. The power safety circuit as claimed in claim 1 , wherein said output terminal is connected to a high-side switch.

10. The power safety circuit as claimed in claim 1 , wherein said output terminal is a reset pin.

11. An integrated circuit device comprising:
a power source; and
at least one power safety circuit, wherein the at least one power safety circuit comprises
a power sense terminal,
an output terminal,
an output driver unit connected to said output terminal,
an input terminal connectable to receive a first power from the power source and arranged to supply said first power to said output driver unit, and
a power detection unit arranged to detect a state of said input terminal and provide a power sense signal to said power sense terminal, wherein said power sense terminal is arranged to supply a second power to said output driver unit when said power sense signal indicates that a level of said first power is below a minimum level for driving said output terminal, and wherein a level of said second power is lower than said level of said first power.

12. The integrated circuit device as claimed in claim 11 , wherein said level of said first power being below said minimum level corresponds to an absence of said first power.

13. The integrated circuit device as claimed in claim 11 , wherein said output terminal is a fail safe terminal.

14. The power safety circuit as claimed in claim 11 , wherein said output driver unit is arranged to drive said output terminal in a fail safe state when receiving said second power.

15. The power safety circuit as claimed in claim 11 , wherein said power detection unit comprises a power-on reset detection circuit.

16. The power safety circuit as claimed in claim 11 , wherein said output driver unit comprises a dedicated low power circuit arranged to drive said output terminal when receiving said second power from said power sense terminal.

17. The power safety circuit as claimed in claim 11 , wherein said power detection unit is arranged to control a provision of said second power by said power sense terminal.

18. A method, comprising
receiving, at an input terminal of a power safety circuit, a first power from a power source;
supplying, by the input terminal, the first power to an output driver unit of the power safety circuit;
detecting, by a power detection unit, a state of the input terminal;
providing, by a power detection unit, a power sense signal to a switching unit based on the state of the input terminal;
connecting, by the switching unit, a power sense terminal of the power safety circuit to the output driver unit in response to the power sense signal; and
supplying, by the switching unit, the second power to the output driver unit in response to an indication in said power sense signal that a level of said first power is below a minimum level for driving said output terminal, wherein a level of said second power is lower than said level of said first power.

19. The power safety circuit as claimed in claim 1 , comprising a switching unit arranged to connect said power sense terminal to said output drive unit depending on said power sense signal.

Assignees

• Givelin Philippe
• Bernon-Enjalbert Valerie
• Founaud Guillaume
• Nxp Usa Inc

Inventors

• Givelin Philippe
• Bernon-Enjalbert Valerie
• Founaud Guillaume

Classifications

• Y10T307/615

  Cross-Sectional Technologies · mapped topic

• B60T8/885

  using electrical circuitry · CPC title

• B60R21/0173 Primary

  Diagnostic or recording means therefor · CPC title

• B60T2270/414

  Power supply failure · CPC title

• H02J9/061 Primary

  for DC powered loads · CPC title