DUAL-MODE DATA CARRIER AND CIRCUIT FOR SUCH A DATA CARRIER WITH IMPROVED MODE CHANGE-OVER

摘要

A data carrier (1) which can be operated in a contact-bound mode and in a contactless mode and a circuit (1A) for such a data carrier (1) has a.c. detection means (69) for detecting the presence of a useful HF signal (HF) received via a transmission coil (31) and clock signal detection means (73) for detecting a clock signal (CLK1) received via a transmission contact (16), and has logic means (82) which cooperate with the a.c. detection means (69) and the clock signal detection means (73) and which enable the activation of the contact-bound mode (CONTACT) and the activation of the contactless mode (CONTACTLESS) to be initiated.