Shutdown protection for bus line drivers

• US 9,172,235 B2
• Filed: 06/03/2013
• Issued: 10/27/2015
• Est. Priority Date: 06/03/2013
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Metzner, Dieter, Widerin, Peter, Wallner, Paul, Rickes, Thomas
• Primary Examiner(s): Tran, Thienvu
• Assistant Examiner(s): Comber, Kevin J
• Application Number:
  US13/908,770
• Publication Number:
  US 20140355158A1
• Time in Patent Office: 876 Days
• Field of Search: 361/63
• US Class Current: 1/1
• CPC Class Codes: H02H 3/08 responsive to excess current responsive to abnormal temperature caused by excess current H02H5/04
• CPC Class Codes: H04L 25/0272 Arrangements for coupling to multiple lines, e.g. for differential transmission
• CPC Class Codes: H04L 25/0282 Provision for current-mode coupling

Abstract

An electrical circuit for driving a bus is described that includes a plurality of branches coupled to at least one signal line at a termination of the bus and a transmit data input configured to receive data that the electrical circuit drives across the bus. The electrical circuit also includes an over-current validation unit coupled to the transmit data input which is configured to validate an over-current condition detected at a first branch of the plurality of branches based at least in part on the data at the transmit data input. The electrical circuit also includes a branch control unit coupled to the over-current validation unit which is configured to disable at least one of the plurality of branches in response to a validated over-current condition at the first branch.

Claims

1. An electrical circuit for driving a bus, comprising:

a plurality of branches coupled to at least one signal line at a termination of the bus;

a transmit data input configured to receive data that the electrical circuit drives across the bus;

an over-current validation unit coupled to the transmit data input, wherein the over-current validation unit is configured to validate an over-current condition detected at a first branch of the plurality of branches based at least in part on the data at the transmit data input; and

a branch control unit coupled to the over-current validation unit and configured to disable at least one of the plurality of branches in response to a validated over-current condition at the first branch.

2. The electrical circuit of claim 1, wherein the over-current condition is a first over-current condition and the over-current validation unit is further configured to:

validate the first over-current condition detected at the first branch based at least in part on the data at the transmit data input and a second over-current condition detected at a second branch of the plurality of branches.

3. The electrical circuit of claim 2, wherein the second over-current condition is not a validated over-current condition at the second branch.

4. The electrical circuit of claim 1, wherein the over-current condition is a first over-current condition detected at a first point in time and the over-current validation unit is further configured to:

validate the first over-current condition based at least in part on the data at the transmit data input and a second over-current condition detected at the first branch at a second point in time subsequent to the first point.

5. The electrical circuit of claim 1, wherein the over-current validation unit is further configured to:

validate the over-current condition based at least in part on a quantity of valid over-current conditions counted at the first branch within a predetermined amount of time.

6. The electrical circuit of claim 5,

wherein the predetermined amount of time is based on a bit length of the data.

7. The electrical circuit of claim 1, wherein the over-current validation unit is further configured to:

validate the over-current condition at a point in time which is at least a predetermined amount of time subsequent to a first change of the data at the transmit data input.

8. The electrical circuit of claim 1, further comprising:

a current detection unit coupled to the plurality of branches, wherein the current detection unit is configured to detect a current through each of the plurality of branches including the first branch; and

an over-current determination unit coupled to both the current detection unit and the transmit data input, wherein the over-current determination unit is configured to detect the over-current condition at the first branch based on the current at the first branch and the data at the transmit data input.

9. The electrical circuit of claim 1, further comprising:

wherein the plurality of branches are arranged in an H-bridge configuration at the termination unit.

10. A method comprising:

detecting an over-current condition at a first branch of a plurality of branches of a driver unit coupled to a bus for driving at least one signal line of the bus;

validating the over-current condition based at least in part on data at a transmit data input of the driver unit; and

disabling at least one branch of the plurality of branches in response to validating the over-current condition at the first branch.

11. The method of claim 10,

wherein validating the over-current condition is in response to a change in the data at the transmit data input of the driver unit.

12. The method of claim 10,

wherein validating the over-current condition is further based at least in part on a value of the data at a transmit data input.

13. The method of claim 10,

wherein validating the over-current condition is further based at least in part on an over-current condition or a lack of an over-current condition detected at one or more branches of the plurality of branches other than the first branch.

14. The method of claim 10, wherein the over-current condition is a first over-current condition detected at a first point in time, the method further comprising:

detecting a second over-current condition at the first branch at a second point in time subsequent to the first point;

validating the second over-current condition based at least in part on the data at the transmit data input; and

disabling the at least one branch of the plurality of branches in response to validating the first and second over-current conditions.

15. The method of claim 14,

wherein a quantity of time between the first and second points in time is less than a bit length of the data.

16. The method of claim 10, wherein disabling the at least one branch of the plurality of branches further comprises:

adjusting a position of a switch associated with the at least one branch to at least partially open the switch.

17. The method of claim 10, wherein disabling the at least one branch of the plurality of branches further comprises:

increasing a resistance of a resistor associated with the at least one branch.

18. The method of claim 10, further comprising:

detecting a current through the first branch; and

in response to detecting the change in the data, determining the over-current condition at the first branch based at least in part on the detected current and a value of the data.

19. The method of claim 10,

wherein the plurality of branches are arranged in an H-bridge configuration.

20. A device comprising:

means for detecting an over-current condition at a first branch of a plurality of branches of a driver unit coupled to a bus for driving at least one signal line of the bus;

means for validating the over-current condition based at least in part on data at a transmit data input of the driver unit and in response to a change in the data; and

means for disabling at least one branch of the plurality of branches in response to validating the over-current condition at the first branch.

21. The device of claim 20, wherein the over-current condition is a first over-current condition detected at a first point in time, the device further comprising:

means for detecting a second over-current condition at the first branch at a second point in time subsequent to the first point;

means for validating the second over-current condition based at least in part on the data at the transmit data input; and

means for disabling the at least one branch of the plurality of branches in response to validating the first and second over-current conditions.

22. The device of claim 20, further comprising:

means for validating the over-current condition based at least in part on a quantity of valid over-current conditions counted at the first branch within a predetermined amount of time.

23. The device of claim 20, further comprising:

means for detecting a current through the first branch; and

in response to detecting the change in the data, means for determining the over-current condition at the first branch based at least in part on the detected current and a value of the data.