Abstract:
The power supply device has a temporary energy store, a main energy store, and a switching device. The switching device has three switching states. The temporary energy store is connected in the first switching state to a power supply input and is connected in the second switching state to the main energy store, which is connected to a power supply output. An energy discharge device is connected to the temporary energy store in the third switching state of the switching device which follows directly the second switching state.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]    This application is a continuation of International Application No. PCT/DE99/02717, filed Aug. 31, 1999, which designated the United States.  
     
    
     
       BACKGROUND OF THE INVENTION  
       Field of the Invention  
         [0002]    The invention lies in the electronics art and pertains, more specifically, to a power supply device and to a circuit configuration having the power supply device.  
           [0003]    Japanese patent Abstracts JP 61161967 discloses a power supply device having a temporary energy store, a main energy store and a switching device. The switching device has two switching states. In a first switching state, the temporary energy store is connected to a power supply input and in a second switching state it is connected to the main energy store. The latter is connected to a power supply output. The same applies to European published patent application EP 0 818 875 A2.  
           [0004]    European published patent application EP 0 386 261 A1 discloses a similar configuration, with the temporary energy store being switched by means of two switching devices which alternately drive the input and output of the temporary energy store. Furthermore, a configuration for controlling a switching device in a power supply device is described in U.S. Pat. No. 5,278,489.  
           [0005]    There exists an increasing need to provide a data processing circuit with secure power supplies. This requirement arises from the fact that there is an increasing need in data processing technology to check whether a data processing circuit may or may not be operated. Attempts are increasingly being made to circumvent such measures, which are based on identification or authentication involved in the process and checking whether operation is or is not allowed. One possibility for gaining unauthorized access to operations or data in a data processing device is the possibility of detecting changes in the power consumption of the data processing device during authorized operation. These changes can then be used to gain access to specific processes and/or data to which access is intrinsically not allowed.  
         SUMMARY OF THE INVENTION  
         [0006]    The object of the present invention is to provide a power supply device, and a circuit configuration with a data processing device, which overcome the above-noted deficiencies and disadvantages of the prior art devices and methods of this general kind, and wherein it is not possible to deduce any processes or data in the data processing device by monitoring the power consumption.  
           [0007]    With the above and other objects in view there is provided, in accordance with the invention, a power supply device, comprising:  
           [0008]    a power supply input and a power supply output;  
           [0009]    a switching device having a first switching state, a second switching state, and a third switching state temporally following the second switching state;  
           [0010]    a main energy store connected to the power supply output;  
           [0011]    a temporary energy store connected to the power supply input in the first switching state and to the main energy store in the second switching state of the switching device; and  
           [0012]    an energy discharge device connected to the temporary energy store in the third switching state of the switching device.  
           [0013]    In accordance with an added feature of the invention, the switching device is one of a plurality of switching devices and the temporary energy store is one of a plurality of temporary energy stores respectively associated with the switching devices and selectively connectible in parallel with one another to the power supply input and to the main energy store.  
           [0014]    In accordance with an additional feature of the invention, the plurality of temporary energy stores are connected to the power supply input at different predetermined times.  
           [0015]    In accordance with another feature of the invention, the plurality of temporary energy stores are simultaneously connected to the main energy store.  
           [0016]    With the above and other objects in view there is also provided, in accordance with the invention, an integrated circuit configuration comprising a power supply device as outline above and a data processing device connected to the power supply output. The power supply and the data processor are expediently integrated on a common semiconductor chip.  
           [0017]    In accordance with a concomitant feature of the invention, the switching device is configured to be operated at a frequency which is less than or equal to a maximum operating frequency of the data processing device.  
           [0018]    By decoupling the charged temporary energy store from the power supply input and by changing the charge on the main energy store, the power consumption which can be observed at the power supply input is independent of the instantaneous value of the power consumption which can be observed at the power supply output or which is caused by the data processing device, since the temporary energy store is connected to an energy discharge device once the charge has been transferred to the main energy store.  
           [0019]    Other features which are considered as characteristic for the invention are set forth in the appended claims.  
           [0020]    Although the invention is illustrated and described herein as embodied in a power supply device, and a circuit configuration having this power supply device, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.  
           [0021]    The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]    [0022]FIG. 1 is a schematic circuit diagram of a first exemplary embodiment according to the invention;  
         [0023]    [0023]FIG. 2 is a schematic circuit diagram of a development of the exemplary embodiment illustrated in FIG. 1;  
         [0024]    [0024]FIG. 3 is a schematic circuit diagram of a further refinement of the exemplary embodiment of the invention illustrated in FIG. 1; and  
         [0025]    [0025]FIG. 4 is a diagram of a second exemplary embodiment.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0026]    Referring now to the figures of the drawing in detail and first, particularly, to FIG. 1 thereof, there is seen a first exemplary embodiment according to the invention. In this case, the figure shows that a voltage U is applied to an input E and is supplied to a switch S when the switch S assumes a first switching state Z 1 . In the first switching state, the voltage is also supplied to a capacitor CZ. In the process, the capacitor CZ is charged to the value of the voltage U applied to the input E. When the switch S assumes the second state Z 2 , then the capacitor CZ is no longer connected to the input E, but is connected to a capacitor C which is in turn charged by the capacitor CZ. The voltage UV applied to the capacitor C is present at the output A and is used as a supply voltage for a data processing device  1 , which is likewise connected to the node A. The operation of the data processing device  1  once again results in power being consumed, so that the capacitor C is discharged. The switch S must therefore be switched back to the state Z 1 , so that the capacitor CZ is recharged and, once the switch S has been switched back to the state Z 2 , recharges the capacitor C once again.  
         [0027]    The data processing device  1  is in turn intended to be operated at clock rate T. If the switching frequency which is used in order to recharge the capacitor C repeatedly is less than twice the clock rate T, then it is not possible to use the charging current which is used to charge the capacitor CZ to deduce the current with which the data processing device  1  is being operated from the capacitor C.  
         [0028]    A simple low-pass filter attenuates the high frequencies and thus makes it harder to deduce the function, although the actual current profile can be made visible once again by appropriate amplification.  
         [0029]    The configuration in the form of a sampling filter now makes it possible to use a switching frequency (sampling frequency) which is less than twice the clock frequency of the circuit to deliberately contravene the sampling theorem and thus to make it considerably more difficult to reconstruct the original current profile. The desired corruption becomes greater the lower the switching frequency in comparison to the clock frequency.  
         [0030]    Reconstruction can be made even more difficult by varying the switching frequency with time.  
         [0031]    Referring now to FIG. 2, there is shown a development of the exemplary embodiment illustrated in FIG. 1. Here, identical and comparable elements are denoted by the same reference symbols. In this development, a large number, that is to say a number N, of capacitors Z 1  to ZN are provided, which are charged with the voltage U from the voltage input via respective switches S 1  to SN. The invention now provides either for the capacitors to be charged at the same time using the input voltage U in order after this to be connected successively in parallel to the capacitor C. This reduces the voltage ripple on the capacitor C, without any more information being transmitted to the input E. A further option is to connect the capacitors CZ 1  to CZN sequentially in a complex sequence to the input E and to the capacitor C. In both cases, the charging current drawn from the input voltage is made uniform or is smooth. Furthermore, it is possible in both cases for the described arrangement to be operated as a voltage regulator for the data processing device  1 . In this case, the clock switching rate T is regulated as a function of the current drawn, that is to say as a function of the supply voltage UV.  
         [0032]    Referring now to FIG. 3, there is shown a further development of the exemplary embodiment illustrated in FIG. 1. Here, the switch S has a third state Z 3 . Furthermore, a parallel voltage regulator  2  is provided in parallel with the capacitor C and the data processing device  1 . The difference in operation, as is shown in FIG. 3, to the arrangement illustrated in FIG. 1 is that, once the charge stored on the capacitor CZ has been moved to the capacitor C, the switch S assumes the state Z 3 . In this position, the capacitor is connected in parallel with a discharge circuit  3 . This discharge circuit  3  at that point discharges the capacitor CZ to a predetermined value. The switch S then switches back to the state Z 1 , so that the capacitor CZ is connected to the input E, so that it is once again charged from the input voltage U. In this way, the capacitor CZ is in a predetermined state before being recharged, so that it is always charged with the same charging current from the input voltage U.  
         [0033]    All three refinements of the first exemplary embodiment according to the invention are suitable for being constructed in the form of an integrated circuit on a semiconductor chip.  
         [0034]    In this case, for example for a data processing device which requires a supply voltage of two volts and is operated with a mean power loss of 2 milliwatts and with a switching frequency of 1 MHz and an input voltage of 3 volts, a capacitance of 1 nF is required for the capacitor CZ. A current of 1 mA is transmitted in this case. The switch S in a case such as this is in the form of a conventional electronic switch. The circuit configuration is preferably for use in integrated circuits which are produced based on the technology using ferroelectric dielectrics. In a case such as this, the dielectric constant ε which can be used is greater than the previously used dielectric constants, so that a smaller area is required for a predetermined capacitance in a case such as this.  
         [0035]    Referring now to FIG. 4, there is shown a second exemplary embodiment. Here, the capacitance CZ as shown in FIGS.  1  to  3  is replaced by an inductance. The following situation is brought about by switching the switch S from the state Z 1  to the state Z 2 . In the state Z 1  a current I(T) is forced to flow into the inductance L, and thus forms a magnetic field. This magnetic field corresponds to magnetic energy stored in this coil. When the switch S changes from the state Z 1  to the state Z 2 , then the coil is once again connected to the capacitor C which is once again charged by a charging current to a voltage UV(T) drawn from the magnetic energy stored in the inductance L. In order to prevent over-voltages occurring when switching from the state Z 1  to the state Z 2 , a so-called freewheeling diode D must be provided in parallel with the inductance L. If it is not possible to integrate the inductance L on the semiconductor chip, then it can be arranged at least directly on the surface of the semiconductor chip. It will be understood that the developments and variations shown in FIGS. 2 and 3 can be transferred in a corresponding manner to the second exemplary embodiment.