Method for operating an electronic module supplied with electrical energy by an operating voltage source

Abstract

1. A method for operating an electronic module which is supplied with electrical energy by an operating voltage source with a circuit unit for carrying out at least one system function, wherein in the event of an operating voltage interruption the operating voltage is supplied by a system-autonomous capacitor and wherein the system function can be activated by means of the energy reserve supplied by a function-autonomous capacitor and in which furthermore the system-autonomous capacitor is charged by a voltage converter connected to the operating voltage source. 2.1. From DE 197 15 571 A1 a control circuit for security units is known, wherein an up-converter fed by an on-board supply system supplies a system-autonomous capacitor, whose charging voltage serves as an operating voltage for the subsequently connected circuit units, in particular a down-converter, which on its part supplies for example ignition power modules as concerns the operating voltage, each of these power modules comprising its own ignition-autonomous capacitor. 2.2. In accordance with the invention the method is characterized in that the function-autonomous capacitor is connected to the voltage converter by means of a charging connection and that it can be controlled in order to fulfil various functions in different operating states, and that is both in a switching mode for clocking the charging current charging the function-autonomous capacitor, and in a current source mode wherein the charging connection operates as a controlled resistance, both for producing a constant discharging current for checking the system-autonomous capacitor and for producing a re-loading current for re-loading the function-autonomous capacitor.

1 . A method for operating an electronic module ( 10 ) supplied with electrical energy by an operating voltage source (U Bat ) with a circuit unit ( 3 ) for carrying out at least one system function, wherein in the event of an operating voltage interruption the operating voltage (U S ) is supplied by a system-autonomous capacitor (C S ) and the system function can be activated by means of the energy reserve supplied by a function-autonomous capacitor (C Z ) and wherein furthermore the system-autonomous capacitor (C S ) is charged by a voltage converter ( 1 ) connected to the operating voltage source (U Bat ), characterized in that the function-autonomous capacitor (C S ) is connected to the voltage converter ( 1 ) and to the system-autonomous capacitor (C S ) by means of a charging connection ( 5 ) and in that said charging connection ( 5 ) is controllable in following operating states: 
 a) as a switch for clocking the charging current charging the function-autonomous capacitor (C S ), and    b) as a controllable resistance for producing a constant discharging current for checking the system-autonomous capacitor (C S ) and for producing a re-loading current for re-loading the function-autonomous capacitor (C Z ).    
     
     
         2 . A method according to  claim 1 , characterized in that for checking the system-autonomous capacitor (C S ) it is discharged into the function-autonomous capacitor (C Z ).  
     
     
         3 - 5 . (canceled)  
     
     
         6 . A method according to  claim 1 , characterized in that the charging connection ( 5 ) is established by means of at least one transistor element (T) and by a resistance (R) which is series-connected to it.  
     
     
         7 . A method according to  claim 1 , characterized in that an up-converter is used as a voltage converter ( 1 ).  
     
     
         8 . Use of the method according to  claim 1  in a motor vehicle control device with a power module ( 3 ) as a circuit unit for triggering a security unit ( 4 ), wherein in the event of an operating voltage interruption the system function is the provision of the ignition energy by means of an ignition-autonomous capacitor (C Z ).