(EN) A semiconductor component (200) is suitable for limiting transient voltages on the supply lines (42, 44) of a system having at least three supply lines, one of the supply lines being a current sink. The semiconductor comprises: at least three input means (30) for connection to respective ones of the supply lines; and for each input means, a respective overvoltage-triggered semiconductor protection unit (10'). Each protection unit comprises a multi junction diode which has a threshold voltage at which it changes from a high-impedance state to a low-impedance state and a respective further diode connected in shunt with it and in the opposite sense to it. Each multi- junction diode is connected in the same sense between a respective input means (30) and a common terminal (32); and each protection unit is adapted to use a lateral turn on current. A shielding diffusion (50) is provided between adjacent protection units (10') for blocking lateral current flow between the adjacent protection units (10').