Ldo overshoot protection

A circuit comprising:

• a DC-DC converter configured to receive a main supply voltage and to generate a first regulated output voltage from the main supply voltage;
• an LDO comprising:
• an input configured to receive the first regulated output voltage,
• an output transistor having a current path coupled between the input of the LDO and an output of the LDO, and
• an error amplifier having an output coupled to a control terminal of the output transistor, a first input configured to receive a reference voltage, a second input coupled to the output of the LDO, and a supply terminal configured to receive the main supply voltage to power the error amplifier, wherein the LDO is configured to generate a second regulated output voltage from the first regulated output voltage at the output of the LDO;
• a capacitor coupled to the input of the LDO;
• and
• a switch coupled to the input of the LDO and configured to discharge the capacitor when the main supply voltage falls below a predetermined threshold.

A circuit comprising:

• a main supply terminal configured to receive a main supply voltage;
• a DC-DC converter having an input coupled to the main supply terminal and an output coupled to an intermediate supply terminal;
• an LDO comprising:
• an output transistor having a current path coupled between the intermediate supply terminal and an output terminal of the LDO, and
• an error amplifier having an output coupled to a control terminal of the output transistor, a supply terminal coupled to the main supply terminal and configured to receive the main supply voltage for powering the error amplifier, a first input coupled to the output terminal of the LDO, and a second input;
• a capacitor coupled to the intermediate supply terminal;
• and
• a switch coupled to the intermediate supply terminal and configured to discharge the capacitor when the main supply voltage falls below a predetermined threshold.