Overvoltage Clamp With Parallel Controlled Resistive Path

Overvoltage protection circuit comprising:

• a first terminal (V+) and a second terminal (V−) for receiving a supply voltage (VL) at a load;
• a voltage clamping circuit connected between said terminals (V+, V−) and providing an clamping current path (CCP) between said terminals (V+, V−) as soon as supply voltage (VL) over said terminals (V+, V−) reaches a preset clamping voltage (VCLP) such that said supply voltage (VL) is substantially limited to said clamping voltage (VCLP), wherein the overvoltage protection circuit further comprises a controllable resistance circuit connected between said terminals (V+, V−) parallel to the voltage clamping circuit, wherein the controllable resistance circuit is configured for providing a resistive current path (RCP) parallel to the clamping current path (CCP) of the voltage clamping circuit when the voltage clamping circuit is activated such that it conducts an electrical current (Icl), and for providing a high-impedance parallel to the clamping current path (CCP) of the voltage clamping circuit when voltage clamping circuit is deactivated;
• wherein the current through the voltage clamping circuit is detected and triggers the controllable resistance circuit to provide the resistive current path (RCP) parallel to the clamping current path (CCP);
• wherein the controllable resistance circuit is configured for changing an effective resistance of the resistive current path (RCP) over time after triggering of the controllable resistance circuit;
• wherein the controllable resistance circuit is configured for selectively activating at least one parallel resistive path by means of at least one respective switching element for setting the effective resistance of the resistive current path (RCP) by connecting at least a subset of the at least one resistive path in parallel with the clamping current path (CCP)
• wherein the selective activation of at least one parallel resistive path is controlled by a state-machine comprising a digital control circuit for digitally controlling the controllable resistance circuit.