Charge-Pump Voltage Divider Startup Circuit Inrush Current Control
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Solution Overview
Problem
The existing charge-pump voltage divider experiences an instantaneous large inrush current during startup, which can lead to switches M1 and M3 being burned down due to the voltage across capacitor Cout being zero when switches M1 and M3 are turned on.
Innovation Solution
A start-up circuit is introduced that controls the first switch to operate in the linear region, regulating the inrush current, and includes a mirror current source, control switches, and a load control switch to manage the inrush current and ensure smooth startup without burning down components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If switches M1 and M3 are turned on instantaneously during startup, then the charge-pump voltage divider can start operating, but an instantaneous large inrush current occurs that may burn the switches
Solution Approach 1:
The start-up circuit is activated before the main switches M1 and M3 are turned on. It preliminarily charges capacitor Cout through a controlled current path, ensuring that when M1 and M3 are subsequently switched on, the voltage difference across them is minimized, thereby preventing inrush current and protecting the switches from damage
Solution Approach 2:
The start-up circuit acts as an intermediary component between the input voltage source and the main switching circuit. It provides a controlled intermediate charging path through resistor R1 and diode D1, allowing capacitor Cout to be charged gradually before the main switches operate, thus mediating the harmful inrush current effect
Data Source
AI summary
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.