Abstract:
In a system for providing electrical energy for an electronic circuit adapted to supply power to a load, one terminal for a power supply voltage of the circuit is connected to a positive pole of an energy source, and one terminal for ground for the circuit is connected to a negative pole of the energy source via a rectifying electronic component, and a capacitor is connected between the two terminals of the circuit for partial supply of the circuit with electrical energy.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a system for supplying electrical energy for an electronic circuit and a method for supplying electrical energy. 
       BACKGROUND INFORMATION 
       [0002]    In motor vehicles, the terminal control relay, for example, relay KL15, is triggered for an output of an ignition switch, relay KL50 is triggered for a starter circuit and relay KL75 is triggered for the radio, normally via intelligent switches. These switches are designed either as low-side switches or as high-side switches, depending on the make and model of the vehicle. A trigger of the terminal control relays is usually supplied redundantly from two power supply voltage paths via a high-side switch. With such a design, the terminal control relay may also be operated even during a short-term voltage dip in a startup operation. 
       SUMMARY 
       [0003]    Example embodiments of the present invention provide a system for supplying electrical energy for an electronic circuit designed for supplying a load, a terminal for a power supply voltage of the circuit being connected or connectable to a positive pole of an energy source, and a terminal for ground of the circuit being connected or connectable to a negative pole of the energy source via an electronic component having a rectifying effect, which has a forward direction and a reverse direction, and a capacitor adapted for buffering is connectable between the two terminals of the circuit. 
         [0004]    The electronic circuit, typically having at least one electronic module, may include a metal oxide semiconductor field effect transistor (MOSFET), which in this case is usually connected to the positive pole of the voltage source and may also be arranged as a high-side switch. Furthermore, the module may have a charge pump adapted for supplying electrical energy for the MOSFET, at least during normal operation of the module. 
         [0005]    In addition, the electronic circuit may have a logic circuit, which is connected to the negative pole of the energy source. This system usually has a trigger circuit connected to the electronic circuit, including a driver having an open collector output. It is possible for the logic circuit of the electronic circuit to be connected to the trigger circuit. 
         [0006]    In this system, a rectifying electronic component may be connected upstream from the negative pole of the energy source, which may be arranged as a voltage source, this latter component behaving like a diode and being arranged as a diode in example embodiments of the present invention. The rectifying component allows the current to pass through in only one direction (forward direction), but typically no flow is possible in the other direction (reverse direction). It is provided that the forward direction of the component having a rectifying effect is oriented toward the negative pole. This diode-like rectifying component, for example, an active diode, provides partial supply to the logic unit and the charge pump of the high-side switch. 
         [0007]    In operation of the system having the diode-type component or the active diode and the capacitor designed for buffering, there is a shift in the voltage potential on the electronic circuit or the at least one module of the circuit when there is a dip in the starting voltage. The potential shift together with the diode-type component or the active diode causes only the logic unit and, if necessary, the charge pump of the module to be supplied with power in buffered form via the capacitor. The system thus temporarily has a low value for an undervoltage cutoff. The system having the circuit may also be operated even at a high voltage dip after a startup operation, the voltage optionally dropping to levels below the normal minimum voltage of the circuit. 
         [0008]    The system described here is typically designed as a component of a control unit for a motor vehicle. 
         [0009]    Example embodiments of the present invention provide a method for supplying electrical energy for an electronic circuit having at least one electronic module. The electronic circuit is adapted for supplying power, for example, for controlling another load, for example, a relay. A terminal arranged as a positive terminal for a supply voltage of the circuit is connected to a positive pole of an energy source, and a terminal of the circuit arranged as a ground terminal is connected to a negative pole of the energy source via a rectifying component having a positive direction and a reverse direction, for example, via a diode or active diode. Between the two terminals of the circuit a capacitor adapted for buffering is connected. 
         [0010]    In example embodiments of the method, when a voltage dip occurs, a ground potential of the electronic module is shifted to a value of less than zero volt. With example embodiments of the present invention, a starting pulse for a fixed load triggering via a standard high-side switch, for example, the MOSFET as the module of the circuit, may be implemented. The capacitor is suitable for buffering electrical energy for a charge pump of the MOSFET and for the logic unit, which is usually also situated inside the circuit. 
         [0011]    By using inexpensive standard modules, example embodiments of the present invention provide for a load to be supplied via a high-side switch if the starting voltage dips under elevated demands, for example, from a traditional battery voltage. The selected system or circuit is easily adaptable to strong starting dips in the voltage and is therefore robust. 
         [0012]    The system described herein is adapted to perform all the steps of the aforementioned method. Individual steps of this method may also be performed by individual components of the system. 
         [0013]    In addition, functions of the system or functions of individual components of the system may be implemented as steps of the method. Furthermore, it is possible that steps of the method may be implemented as functions of individual components of the system or of the entire system. 
         [0014]    Additional advantages and aspects of example embodiments of the present invention are set forth in the following description and the accompanying drawings. 
         [0015]    The features mentioned above and those yet to be discussed below may be used not only in the particular combination indicated but also in other combinations or alone. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  shows a diagram of a voltage curve obtained with one implementation of the method according to an example embodiment of the present invention. 
           [0017]      FIG. 2  shows a schematic diagram of a conventional device. 
           [0018]      FIG. 3  shows a schematic diagram of a system according to an example embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    Example embodiments of the present invention are illustrated schematically in the drawings and are described in more detail below with reference to the drawings. 
         [0020]    In the diagram from  FIG. 1 , a curve  22  for a voltage is plotted on a vertical axis  20  as a function of time, which is plotted on a horizontal axis  24 . For curve  22  of the voltage, it is provided that the voltage is 12 volt up to a point in time t 0   26  at which a device  50  described with reference to  FIG. 1  or a system  150  according to an example embodiment of the present invention, which is described with reference to  FIG. 3 , is started. However, a starting voltage dip at which the voltage is reduced by a first voltage difference  30  of 9 volt occurs at a point in time t 1   28  immediately after startup. The period of time between points in time t 0   26  and t 1   28  is usually less than 5 ms. For approximately 15 ms, the voltage remains at a level of 3 volt up to point in time t 2   32  and then increases within a period of 50 ms to a level of 5 volt up to a point in time t 3   34  so that a voltage difference  31  relative to the 12 volt battery voltage is 7 volt. As shown by curve  22 , the voltage remains at the level of 5 volt for approximately 1 second up to point in time t 4   36 . Approximately 100 ms later, curve  22  of the voltage has reached a value of 12 volt for the starting voltage, i.e., the battery voltage up to point in time t 5   38 . 
         [0021]      FIG. 1  thus shows the specification of a starting voltage dip under elevated demands. To ensure starting ability even with a cold and highly discharged battery, the terminal voltage should still be ensured even at a very strong starting voltage dip. 
         [0022]    Device  50 , which is diagramed schematically in  FIG. 2  and is known from the related art, includes a circuit U 1   52  having a MOSFET  54  and a logic circuit  56 , a trigger circuit  58  and a relay  60  or a general load. One input of MOSFET  54  within circuit  52  is connected to a positive pole of an energy source via a first terminal “KL 30 L”  62  and a second terminal “KL 30 R”  64 . A first diode D 1   70  is situated along a first feeder line  66  between first terminal  62  and a node point  68 . A second diode D 2   74  is situated along a second feeder line  72  between second terminal  64  and node point  68 . A positive feeder line  76  runs between node point  68  and the input of MOSFET  54 . One output of MOSFET  54  is connected to relay  60  or to the general load, which includes a switch  78 . In addition, one output of relay  60  or the general load is at ground  80 . Furthermore, it is provided that logic circuit  56  of circuit  52  is connected to trigger circuit  58  and, via a third terminal “KL 31”  82 , is connected to a negative pole of the energy source. 
         [0023]    Device  50  shown in  FIG. 2  does not meet the requirement of a very strong voltage dip according to  FIG. 1 . The low voltage in the range between points in time t 1   28  and t 3   34  is below the operating voltage of circuit U 1   52 . The operating voltage usable for circuit U 1   52  is further reduced by the additional voltage drop across one of diodes D 1   70  or D 2   74 . This low operating voltage is usually outside of the specified range of circuit U 1   52  because a charge pump (not shown here) necessary for operation of MOSFET  54  is no longer functional. 
         [0024]    The system  150  according to an example embodiment of the present invention diagramed schematically in  FIG. 3 , like the device  50  diagramed schematically in  FIG. 2 , includes a circuit U 1   152 , which has as a first component a MOSFET  154  to which a charge pump (not shown here) is assigned and has as a second component a logic circuit  156 . Furthermore, system  150  has a trigger circuit  158  cooperating with circuit U 1   152  and a load  160 , arranged as a relay to be controlled with respect to a state via circuit U 1   152 . One input of circuit  152 , corresponding here to an input of MOSFET  154 , is redundantly connected to a positive pole of an energy source (not shown in  FIG. 3 ) arranged as a battery via a first terminal “KL 30 L”  162  and via a second terminal “KL 30 R”  164 . 
         [0025]    A first diode D 1   170  is situated along a first positive feeder line  166  of first terminal  162  up to a positive terminal  168 . A second diode D 2   174  is situated along a second positive feeder line  172  between second terminal  164  and positive terminal  168 . Between positive terminal  168  and the input of circuit  152  and thus of MOSFET  154  there runs a third positive feeder line  176 . Since MOSFET  154  is connected to the positive pole of the energy source, it is also referred to here as a so-called high-side switch. One output of MOSFET  154  is connected to general load  160 . One output of general load  160  having a switch  178  is at ground  180 . Logic circuit  156  of module  152  is connected, on the one hand, to trigger circuit  158  and, on the other hand, to a negative pole of the energy source via a third terminal “KL 3 1 ”  182 . 
         [0026]    In addition, the system  150  diagramed schematically in  FIG. 3  has a connecting line  188  along which a capacitor  190  provided for buffering is situated, this connecting line being situated between positive terminal  168  and a ground terminal  184  situated along a negative feeder line  186  between logic circuit  156  and third terminal  182 . In the example embodiment of system  150  shown, it is provided that a third diode D 3   192  is situated as a rectifying electronic component having a forward direction and a reverse direction between third terminal  182  and negative terminal  184 . Furthermore, trigger circuit  158  includes a driver  194 , arranged as a transistor, having an open collector output. 
         [0027]    The triggering of a consumer connected to circuit  152  D 1 , i.e., load  160  here, may be ensured even during the starting voltage dip depicted in  FIG. 1  by the system shown in  FIG. 3 . 
         [0028]    Low voltages on circuit  52  U 1  within device  50  shown in  FIG. 2  result in a failure of the charge pump and thus a failure of a switching function of circuit  52  U 1 . 
         [0029]    To keep the charge pump active to supply MOSFET  154  within system  150  from  FIG. 3  during the strong voltage dip, it may be provided that it is to be supplied with a sufficient voltage. In the circuit  152  arranged as an integrated high-side circuit, the charge pump is connected internally to the power supply of power MOSFET  154 . To support the positive supply potential of the charge pump, thus very large capacitances would be necessary in conventional applications. To buffer only the lower operating current of the charge pump and not of the entire load circuit, the rectifying electronic component having one forward direction and one reverse direction and thus additional third diode D 3   192  are inserted into the ground or GND terminal of circuit U 1   152 , and capacitor  190  is connected between positive terminal  168  (VBB) and the GND or ground terminal  184  of circuit U 1   152 . It is provided that the forward direction of third diode D 3   192  is oriented as the rectifying component toward third terminal  182  and thus toward the negative pole. 
         [0030]    Using this additional circuit including capacitor  190  and third diode D 3   192  as a rectifying component, the power supply of logic circuit  156  in circuit U 1   152  is adequately buffered via capacitor  190  to be supplied through capacitor C 1   192  in the period of time between points in time t 1   28  and t 3   34 . In the period of time between points in time t 3   34  and t 5   38 , the power supply voltage is high enough to supply circuit U 1   152  again directly via diodes D 1   170 , D 2   174  and D 3   192 . The additional circuit results in the ground potential of circuit U 1   152  shifting to less than 0 volt in a voltage dip. The resulting level offset in trigger circuit  158  may be compensated, for example, by using an open collector driver.