Abstract: A supply circuit has a first and a second terminal for connecting an accumulator, a third and a fourth terminal for connecting at least one battery, and an output terminal. A voltage regulator is connected to the first terminal on the input side and to a fifth terminal on the output side. An undervoltage detection circuit is adapted to activate the voltage regulator when a voltage at the first terminal is greater than a threshold voltage. A reverse polarity protection device is coupled between the third terminal and the output terminal. A blocking diode is coupled between the fifth terminal and the output terminal.

Abstract: A supply circuit for supplying a light-emitting element includes a voltage regulator having a voltage output for outputting an output voltage and having a control input for regulating the output voltage based on a voltage at a divider node of a voltage divider. A first and a second terminal are used to connect the light emitting element, the first terminal being coupled to the voltage output and the second terminal being coupled to a reference potential terminal via a series resistor. The supply circuit further includes a control block having an analog-to-digital converter for generating a digital voltage feedback value from a voltage applied to the second terminal, a control element, and a digital-to-analog converter coupled to the divider node for outputting an analog control signal based on a digital control value.