Amplifier circuit and method for operating an amplifier circuit

A device for controlling field devices, the device comprising:

• an amplifier circuit acting as a line driver in a transmission line between a central station and field devices connected to the transmission line, the amplifier circuit comprising:
• a DC/DC converter comprising a DC/pulse converter with two electrically isolated switching stages;
• a logic block upstream of the DC/DC converter;
• wherein, the logic block generates control signals for switches of both electrically isolated switching stages from a PWM signal;
• wherein the control signals are fed into the two electrically isolated switching stages by drivers;
• a priority block generating the PWM signal by forwarding at least one of an output signal of a first controller or an output signal of a second controller to the logic block;
• the first controller generating a first fault signal based on a predefined or predefinable voltage limit value and
• an output voltage fed back within the amplifier circuit via a feedback path and sending the first fault signal to the priority block;
• and
• the second controller generating a second fault signal based on a predefined or predefinable current limit value and
• an output current fed back within the amplifier circuit via a feedback path and sending the second fault signal to the priority block;
• and
• the central station defining the current limit value and the voltage limit value at a first input (current set) and a second input (voltage set) respectively.