Method and apparatus for limiting startup inrush current for low dropout regulator

摘要

A low dropout (LDO) regulator with a limited startup inrush current is disclosed. The LDO includes a power source, error amplifier, pass transistor, feedback network, and a current limit control whose input is electrically connected to the pass transistor and the electrical output of the error amplifier and whose output limits current during startup. The LDO can include a current control limit comparator including a power source, and output of the pass transistor. The LDO can also include a bypass mode current control limit comparator having a first input voltage of the error amplifier, and a second input voltage from the error amplifier.

主权项

1. A low dropout device with limiting startup inrush current, the device comprising:
an error amplifier; a pass transistor coupled to said error amplifier; a feedback network electrically connected to said pass transistor wherein an output of said feedback network is electrically coupled to an input of said error amplifier; a current limit control network whose current limit control network input is electrically connected to said pass transistor and an electrical output of said error amplifier and whose current limit control network output provides a current limit; a Bypass mode current control limit comparator, wherein an input of said Bypass mode current control limit comparator comprises a supply voltage, and an output of said pass transistor; a Low Dropout (LDO) mode current control limit comparator, wherein an input of said Low Dropout (LDO) mode current limit comparator comprises a reference voltage and the output of said feedback network; and a Low Dropout (LDO) mode/Bypass mode select network whose inputs are the output of said Low Dropout (LDO) mode current control limit comparator, and said Bypass mode current control limit comparator, and whose Low Dropout (LDO) mode/Bypass mode select network output is coupled to said current limit control network to reduce the current limit at startup of the low dropout device.