Electronic digital logic circuitry – Signal sensitivity or transmission integrity – Signal level or switching threshold stabilization
Reexamination Certificate
2002-02-19
2003-04-01
Le, Don (Department: 2819)
Electronic digital logic circuitry
Signal sensitivity or transmission integrity
Signal level or switching threshold stabilization
C327S512000, C327S378000, C326S082000
Reexamination Certificate
active
06541999
ABSTRACT:
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The invention relates to a configuration and a method for protecting an integrated circuit against over-temperature conditions. Furthermore, the invention relates to an integrated circuit having such a configuration.
During the operation of integrated semiconductor circuits, at least part of the electrical power is converted into heat. Under certain conditions—for example in the event of overload, short circuit, external heating of the semiconductor chip—this can lead to an undesirable over-temperature condition. In order to detect the over-temperature condition and in order to protect the integrated semiconductor circuits, the latter typically have a temperature protection device. However, the latter must satisfy various requirements.
In circuit configurations having a power switch which is configured for switching loads, such as, for example, a DC motor, an asynchronous motor or the like, a short circuit can occur in the load circuit, through which the power switch or even the load to be switched can be destroyed. In order to protect the power switch, the latter is provided with one or more temperature sensors whose signals are evaluated by an evaluation circuit and which shut down the power switch when a short circuit occurs which results in a great increase in temperature in the power switch. When a predetermined temperature threshold is exceeded, the power switch is shut down and thus protected from destruction. In this case, the temperature sensors, which are typically configured as resistors, diodes or transistor sensors, are preferably integrated in the vicinity of the corresponding hot spot, that is to say in the vicinity of the hottest point in the power switch. The signal of the temperature sensor is then processed by an evaluation circuit in such a way that the power switch is shut down or at the very least power is reduced as soon as the temperature present at the temperature sensor exceeds a predetermined temperature threshold, which is dependent on the respective application and which typically lies above 150° C.
Furthermore, temperature sensors are known which are intended to protect the entire integrated circuit from being heated to an excessively great extent. By way of example, the integrated circuit may be heated by an external temperature source, such as, for example, an incandescent lamp driven by the integrated circuit. If the temperature coupled in via the incandescent lamp becomes too high, this can lead to irreversible damage to the integrated circuit, as a result of which the functionality thereof is no longer ensured or it is even destroyed. This applies not only to external heating but also to undesirably great inherent heating. For this purpose, temperature sensors exist which monitor the ambient temperature of the integrated circuit and are preferably disposed in the vicinity of the corresponding hot spot of the integrated circuit. In this case, the so-called “shutdown/restart” principle is typically used, according to which the integrated circuit is shut down if the chip temperature detected by a corresponding temperature sensor exceeds a specific value. Once the semiconductor chip has cooled down, for example by 10° C., the integrated circuit is switched on again. In the event of a disturbance situation, that is to say if the cause of the over-temperature condition has not been eliminated, the integrated circuit is clocked in accordance with the hysteresis resulting from the shutdown and restart temperature. The constant switching on and off in the case of a disturbance represents a major burden on the integrated circuit which in the medium term—if the disturbance is not rectified—will lead undesirably to the failure of the integrated circuit.
In circuit configurations that have a plurality of circuit parts that function independently of one another, as is the case for example with monolithic multi-channel switches, the latter are in each case provided with separate temperature sensors. In the disturbance situation, typically only the defective channel is switched on and off. However, the burden associated with the switching on and off also places a very large burden on the corresponding adjacent channels.
Therefore, two different, partly conflicting requirements result for a temperature sensor. On the one hand, a temperature sensor should have a relatively low threshold for a temperature shutdown, in order that the entire semiconductor chip or the integrated circuit, the housing and further external components are thermally loaded as little as possible in the case of a disturbance. On the other hand, a temperature sensor should have a relatively high threshold for the temperature shutdown in order nevertheless to be functional under certain conditions, for example when an incandescent lamp is switched on or in the event of a momentary, yet not disturbing overload.
The prior art has only disclosed temperature sensors in which the threshold at which a temperature-dictated shutdown of the power switch or of the integrated circuit is affected is adapted in one direction or the other, but does not simultaneously satisfy all the requirements mentioned above.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a circuit configuration with temperature protection and a method for implementing the temperature protection which overcome the above-mentioned disadvantages of the prior art devices and methods of this general type, which is better adapted to the respective requirements, and furthermore, the least possible mutual thermal influencing of the individual circuit parts should be possible in so-called multi-channel ICs.
With the foregoing and other objects in view there is provided, in accordance with the invention, a configuration for protecting an integrated circuit against over-temperature conditions. The configuration contains at least one detector device for identifying a disturbance situation regarding the integrated circuit, at least one temperature sensor for detecting a temperature of at least one part of the integrated circuit, and a logic device for ascertaining a disturbance mode derived from the disturbance situation and/or the temperature. The logic device allocates a first temperature switching stage to the temperature sensor in a normal mode and a second, lower temperature switching stage to the temperature sensor in the disturbance mode. The logic device is connected to both the temperature sensor and the detector device.
With the foregoing and other objects in view there is additionally provided, in accordance with the invention, a method for protecting an integrated circuit against over-temperature conditions. The method includes the steps of checking the integrated circuit for a disturbance situation; checking a temperature of at least one part of the integrated circuit; ascertaining an occurrence of a disturbance mode based on at least one of the disturbance situation and the temperature; and allocating a first temperature switching threshold to a temperature sensor in a normal mode and a second, lower temperature switching threshold to the temperature sensor in the disturbance mode.
With the foregoing and other objects in view there is further provided, in accordance with the invention, an integrated circuit. The integrated circuit has a first terminal for a first supply potential, a second terminal for a second supply potential, and a controllable semiconductor switch disposed between the first terminal and the second terminal. The controllable semiconductor switch has a load path and a control terminal. A load is connected in series with the load path of the controllable semiconductor switch. A drive circuit is coupled to and drives the control terminal of the controllable semiconductor switch. A configuration for protection against over-temperature conditions as described above is provided.
The temperature sensor according to the invention is distinguished by an over-temperature protection configuration configured in at least two stages. The cir
Gergintschw Zenko
Heil Holger
Infineon - Technologies AG
Le Don
Locher Ralph E.
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