Charge-pump voltage divider and associated control method

摘要

The embodiments of the present invention disclose a charge-pump voltage divider and associated start-up method. The charge-pump voltage divider comprises a start-up circuit that can regulate an inrush current during start up. The start-up circuit comprises a switch, which operates in linear region state during start-up, and operates in switching state after the start-up completes. The charge-pump voltage divider may further comprise a load control switch configured to ensure the start-up is independent of a load current.

主权项

1. A charge-pump voltage divider, comprising:
a first switch, a second switch, a third switch and a fourth switch sequentially connected in series between an input terminal and ground; a first capacitor having a first terminal and a second terminal, wherein the first terminal of the first capacitor is coupled to a common connection of the first switch and the second switch, and the second terminal of the first capacitor is coupled to a common connection of the third switch and the fourth switch; a second capacitor having a first terminal and a second terminal, wherein the first terminal of the second capacitor is coupled to a common connection of the second switch and the third switch, and the second terminal of the second capacitor is connected to ground; a start-up circuit comprising the first switch; a load control switch having a first terminal and a second terminal, wherein the first terminal of the load control switch is coupled to a load of the charge-pump voltage divider, and the second terminal of the load control switch is connected to ground; and a logic controller, configured to provide a plurality of control signals to the start-up circuit, the second switch, the third switch, the fourth switch and the load control switch according to an output voltage across the second capacitor of the charge-pump voltage divider; and wherein when the output voltage is lower than a threshold voltage, the plurality of control signals is configured to control the charge-pump to operate in a start-up stage so as to turn the load control switch OFF to disconnect the load from the charge-pump voltage divider, and to operate the first switch in a linear region; when the output voltage is higher than the threshold voltage, the plurality of control signals is configured to turn the load control switch ON to connect the load to the charge-pump voltage divider, and is further configured to switch the first switch ON and OFF alternately; and wherein during the start-up stage of the charge-pump voltage divider, the plurality of control signals is configured to maintain the second switch and the fourth switch ON, and maintain the third switch OFF.