Controlled start-up of a linear voltage regulator where input supply voltage is higher than device operational voltage

摘要

A controlled start-up circuit mechanism in a linear voltage regulator can handle a higher supply voltage at start-up and limits the voltage seen at the devices to be lower than the maximum allowed operation voltage. The circuit may regulate voltage for operating a device coupled to a host when the host supply exceeds that necessary for device operation. The controlled start-up mechanism handles a sudden ramp up or spike of supply voltage relative to the device's operational voltage.

主权项

1. A circuit with a linear voltage regulator that generates a regulated voltage from a high input voltage, the circuit comprising:
a plurality of devices limited to at least one operational voltage, wherein the high input voltage exceeds the at least one operational voltage and the regulated voltage is at or below the at least one operational voltage; a startup mechanism for implementing a startup process that slowly ramps an intermediate voltage to avoid a sudden voltage spike of the high input voltage during the startup process before the high input voltage is settled, the startup mechanism comprising:
a plurality of switches;a resistor divider with one resistor that corresponds with each of the switches; anda control amplifier; and a protection device bias arm comprises devices corresponding to the plurality of devices that generate a bias voltage for the plurality of devices, wherein the protection device bias arm controls a sudden voltage spike of the high input voltage after the startup process and after the high input voltage is settled.