Patent ID: 11934217
Assignee: STMICROELECTRONICS RAZVOJ POLPREVODNIKOV D.O.O.
Field: Control (Instruments)
Classification: CPC G | IPC G

Claim 10:
11. An integrated circuit card system comprising;
a voltage regulator comprising:
an amplifier having a first input coupled to a reference voltage node and a second input coupled to an output node of the voltage regulator,
a first transistor having a first conduction terminal coupled to the output node of the voltage regulator, a second conduction terminal coupled to a first supply terminal configured to receive a first supply voltage provided by a contact reader, and a control terminal selectively coupled between the output node of the amplifier and a first voltage node configured to provide the disabling voltage, and
a second transistor having a first conduction terminal coupled to the output node of the voltage regulator, a second conduction terminal coupled to a second supply terminal configured to receive a second supply voltage provided by an electromagnetic field of a contactless card reader, and a control terminal selectively coupled between the output node of the amplifier and the first voltage node configured to provide the disabling voltage, and
a supply selection circuit configured to
couple the first supply terminal to a power supply input of the amplifier via a supply selection circuit output node when a voltage of the first supply terminal is higher than a voltage of the second supply terminal, and
couple the second supply terminal to the power supply input of the amplifier via the supply selection circuit output node when a voltage of the second supply terminal is higher than a voltage of the first supply terminal, wherein the supply selection circuit comprises: a comparator having inputs coupled to the first supply terminal and the second supply terminal, a first diode coupled between the first supply terminal and a supply terminal of the comparator, a second diode coupled between the second supply terminal and the supply terminal of the comparator, and a capacitor coupled between the supply terminal of the comparator and a supply node.