| 摘要 |
The appliance comprises an IC card reader (3) for an operation with an IC card and a power supply (4) for providing a supply voltage (VCC), in particular for the IC card. The appliance comprises further an overload protection circuit (6), which simulates an IC card extraction in case of an overload of the supply voltage. The power supply (4) is then immediately switched off to avoid any damage for the power supply. In a preferred embodiment, the IC card reader (3) is equipped with a card presence switch (2) for indicating to a micro-controller (5) of the appliance, that an IC card has been inserted into the card reader. The micro-controller provides then a control signal for switching on the power supply for the operation with the IC card. The protection circuit (6) is coupled between the supply voltage for the IC card and the signal line of the card presence switch and provides a detection of a short circuit. The protection circuit may comprise a diode, a comparator or a transistor, which switches off the power supply (4) via a logic circuit (IC3).
|
