Reserve circuit for supplying emergency power to a load in a vehicle

摘要

A reserve circuit for supplying emergency power to an electronic load in a vehicle, for example a passenger vehicle diagnostic apparatus or passenger vehicle accident-data recorder, having - an output connection (U3) to which the load to be supplied with emergency power can be connected, - an input connection (UB) to which an on-board voltage, that is to say, for example, an on-board voltage (UB) fluctuating between 8 and 16 V, is applied via the on-board power supply under normal circumstances, that is to say in normal operating hours, and - a reserve capacitor (C2) for storing an energy reserve, in order, in an emergency, specifically after an unacceptably major drop in the on-board voltage (UB), or after a failure of said on-board voltage (UB), at least for a short time, for example for 20 or 60 seconds, to make available sufficient power for the load, said reserve circuit including a voltage increasing device (V4, L1, T5, D4), which charges the reserve capacitor (C2) to a capacitor voltage (U2), which is more or less stabilised in normal operation and is raised considerably above the maximum on-board voltage (UB) which is usual in normal operation, that is to say of, for example, 16 V. <IMAGE>