System and method for driving an electronic switch dependent on temperature

Patent metadata

Field	Value
Publication number	US-8947064-B2
Application number	US-201113237703-A
Country	US
Kind code	B2
Filing date	Sep 20, 2011
Priority date	Sep 20, 2011
Publication date	Feb 3, 2015
Grant date	Feb 3, 2015

Abstract

An electronic switch is connected in series with a load dependent on an input signal. The electronic switch is operated in a first operation mode for a first time period after a signal level of the input signal has changed from an off-level to an on-level. The first operation mode includes driving the electronic switch dependent on a voltage across the load and dependent on a temperature of the electronic switch. The electronic switch is operated in a second operation mode after the first time period. The second operation mode includes driving the electronic switch dependent on the temperature according to a hysteresis curve.

First claim

What is claimed is:

1. A method for driving an electronic switch connected in series with a load, the method comprising:
operating the electronic switch in a first operation mode for a first time period, wherein the first time period comprises a time period that starts from when a signal level of an input signal has changed from an off-level to an on-level and ends after an expiration of a first predetermined delay time after the first time period starts, wherein operating the electronic switch in the first operation mode comprises driving the electronic switch dependent on a voltage across the load and dependent on a temperature of the electronic switch; and
operating the electronic switch in a second operation mode after the first time period ends, wherein operating the electronic switch in the second operation mode comprises driving the electronic switch dependent on the temperature according to a hysteresis curve.

2. The method of claim 1 , wherein operating the electronic switch in the first operation mode comprises operating the electronic switch in a first current limiting mode in which current through the electronic switch is limited to a first current limit.

3. The method of claim 1 , further comprising:
operating the electronic switch in the second operation mode before the end of the first time period when the temperature rises above a given temperature threshold but the load voltage does not meet a condition associated with an increase of the temperature above the given temperature threshold.

4. The method of claim 1 , wherein operating the electronic switch in the second operation mode comprises:
driving the electronic switch in a third current limiting mode in which the current through the electronic switch is limited to a third current limit; and
switching the electronic switch off when in the third current limiting mode the temperature rises above a third temperature threshold until the temperature decreases to a temperature that is below the third temperature threshold.

5. The method of claim 4 , wherein operating the electronic switch in the first operation mode comprises operating the electronic switch in a first current limiting mode in which current through the electronic switch is limited to a first current limit, wherein the third current limit equals the first current limit.

6. The method of claim 4 , further comprising:
when a current through the load reaches the third current limit, generating a status signal indicating that the third current limit has been reached, and
when the electronic switch is switched off when in the second operation mode the temperature rises above the third temperature threshold, generating a status signal indicating that the electronic switch has been switched off.

7. The method of claim 1 , further comprising:
evaluating a duration of the off-level of the input signal before the on-level;
operating the electronic switch in the first operation mode, when the duration of the off-level has been longer than a first off-period; and
operating the electronic switch in the second operation mode, when the duration of the off-level has been shorter than a second off-period that is shorter than the first off period.

8. The method of claim 7 ,
wherein the first off period is between 1 second and 3 seconds, and
wherein the second off period is between 0.3 seconds and 1 second.

9. The method of claim 7 , further comprising:
operating the electronic switch in a fourth current limiting mode in which a current through the load is limited to a fourth current limit when the duration of the off-level has been longer than the second off-period but shorter than the first off-period.

10. The method of claim 1 , wherein the first predetermined delay time is between 50 ms and 500 ms.

11. The method of claim 1 wherein the electronic switch comprises a transistor.

12. A method for driving an electronic switch connected in series with a load, the method comprising:
operating the electronic switch in a first operation mode for a first time period after a signal level of an input signal has changed from an off-level to an on-level, wherein operating the electronic switch in the first operation mode comprises driving the electronic switch dependent on a voltage across the load and dependent on a temperature of the electronic switch;
operating the electronic switch in a second operation mode after the first time period, wherein operating the electronic switch in the second operation mode comprises driving the electronic switch dependent on the temperature according to a hysteresis curve;
wherein operating the electronic switch in the first operation mode comprises operating the electronic switch in a first current limiting mode in which current through the electronic switch is limited to a first current limit; and
wherein operating the electronic switch in the first operation mode further comprises operating the electronic switch in a second current limiting mode in which the current through the electronic switch is limited to a second current limit higher than the first current limit, when in the first current limiting mode, the temperature rises above a first temperature threshold and the voltage across the load meets a first condition.

13. The method of claim 12 , wherein operating the electronic switch in the first operation mode further comprises switching the electronic switch off when the temperature rises above a second temperature threshold higher than the first temperature threshold and when the voltage across the load meets a second condition different from the first condition.

14. The method of claim 13 , wherein the first temperature threshold is between 125° C. and 175° C. and wherein the second temperature threshold is between 175° and 225° C.

15. The method of claim 13 ,
wherein the voltage across the load meets the first condition when the voltage across the load is above a first voltage threshold and/or when an increase of the voltage across the load over time is above a first voltage increase threshold; and
wherein the voltage across the load meets the second condition when the voltage across the load is above a second voltage threshold that is higher than the first voltage threshold and/or when an increase of the voltage across the load over time is above a second voltage increase threshold that is higher than the second voltage increase threshold.

16. The method of claim 15 ,
wherein the voltage across the load meets the first condition when the voltage across the load is above the first voltage threshold;
wherein the voltage across the load meets the second condition when the voltage across the load is above the second voltage threshold; and
wherein the second voltage threshold is at least 2 times the first voltage threshold.

17. The method of claim 15 ,
wherein the voltage across the load meets the first condition when the increase of the voltage across the load over time is above the first voltage increase threshold;
wherein the voltage across the load meets the second condition when the increase of the voltage across the load over time is above the second voltage increase threshold; and
wherein the second voltage increase threshold is at least 2 times the first voltage increase threshold.

18. The method of claim 15 , further comprising applying a supply voltage to a series circuit that includes the electronic switch and the load;
wherein the voltage across the load meets the first condition when the voltage across the load is above the first voltage threshold;
wherein the vol

Assignees

• Feldtkeller Martin
• Infineon Technologies Austria

Inventors

• Feldtkeller Martin

Classifications

• G05F1/573

  with overcurrent detector · CPC title

• G05F1/567

  for temperature compensation · CPC title

• H02H5/048

  additionally responsive to excess current due to heating of the switch · CPC title

• H03K17/0822 Primary

  in field-effect transistor switches · CPC title

• H03K2017/0806

  against excessive temperature · CPC title