Communication interface with automatic adaptation of the level of the input signal

1. A communication interface, comprising:

an input terminal (Rx) for receiving a logic signal from a remote interface (IF 2 );

a logic level discriminator coupled to the input terminal;

a peak detector connected to store the peak value of the signal at the input terminal; and

a voltage follower connected to the discriminator for providing an auxiliary supply voltage (Vdd 2 ′) based on the value provided by the peak detector;

an electrostatic discharge (ESD) protection device, including:

a first diode (D 1 ) and an RC-circuit configured as the peak detector, connected in series between the input terminal (Rx) and a first power supply line (Vss 1 );

a transistor (MN 1 ) connected between the first power supply line (Vss 1 ) and the input terminal (Rx) through the first diode (D 1 ) or a second diode (D 1 ′); and

inverter configured to turn on the transistor when the voltage across the capacitor of the RC-circuit is less than a threshold.

2. The interface of claim 1 , further comprising:

an output terminal (Tx) designed to provide a logical outgoing signal to the remote interface (IF 2 ); and

an amplifier connected to control the output terminal from the auxiliary supply voltage.

3. The interface of claim 1 , comprising a stack of diodes connected across the capacitor.

4. The interface of claim 1 comprising:

a switchable attenuator connected between the input terminal (Rx) and the discriminator; and

a comparator connected to switch the attenuator into the circuit when the supply voltage (Vdd 1 ) of the interface is less than the peak value supplied by the peak detector (Vdd 2 ).

5. The interface of claim 1 , further comprising a voltage elevator configured to supply the voltage follower at a voltage (Vdd 1 ′) greater than the supply voltage of the interface.