Power-on reset circuity for low battery voltages

An integrated circuit with a power-on reset circuitry to activate the rest of the integrated circuit based on an external supply voltage supplied at a supply pin of the integrated circuit, the power-on reset circuity comprising:

• a fine POR detector built to compare the external supply voltage with a bandgap reference voltage, generated by a bandgap module of the integrated circuit, to detect a rise of the external supply voltage beyond a power-on reset threshold voltage to reset the integrated circuit at power-on and
• a low-dropout regulator to provide an intermediate supply voltage for internal blocks of the integrated circuit that would be damaged by a higher damage voltage which damage voltage is below a maximal voltage of the external supply voltage at the supply pin,
• wherein the power-on reset circuity comprises:
• a switch built to enable in a first switch mode to connect the internal blocks and bandgap module with the supply pin and disconnect them from the intermediate supply voltage during ramp-up of the external supply voltage before the power-on reset and built to enable in a second switch mode to connect the internal blocks with the intermediate supply voltage and disconnect them from the supply pin after power-on reset.