Boost Capacitor Charge Control Circuit for Voltage Regulator Reliability
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Solution Overview
Problem
Conventional switching voltage regulators face challenges in maintaining sufficient charge in boost capacitors, particularly during discontinuous conduction modes or when the high side and low side switches are in a tri-state, leading to potential depletion of charge and inability to turn on the high side switch due to low voltage levels.
Innovation Solution
A charge delivery circuitry is coupled to the output of a power switch, with charge control circuitry that includes comparators or amplifiers to selectively provide charging current to the boost capacitor, ensuring it remains charged by delivering current when the high side and low side switches are off or in tri-state, and removing charge when necessary to prevent output voltage rise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional switching regulators operate without charge delivery circuitry, then the circuit structure remains simple, but the boost capacitor charge may be depleted during discontinuous conduction modes, preventing high side switch operation
Solution Approach 1:
The charge delivery circuitry proactively charges the boost capacitor during specific intervals (when low side switch is on and inductor current is positive) before the high side switch needs to turn on, ensuring sufficient charge is available to maintain reliable operation during discontinuous conduction modes
2Reliability
If charge delivery circuitry continuously charges the boost capacitor, then the capacitor maintains sufficient charge, but the output voltage may rise excessively and affect normal circuit operation
Solution Approach 1:
The charge delivery circuitry incorporates feedback control that monitors the boost capacitor voltage and inductor current state, selectively enabling charge delivery only when the capacitor voltage falls below a threshold and the low side switch is on with positive inductor current, thereby preventing excessive voltage rise while maintaining sufficient charge
Solution Approach 2:
The charging process is made dynamic and conditional rather than continuous, with the charge delivery enabled/disabled based on real-time detection of circuit state (inductor current direction, switch states, capacitor voltage level), allowing the system to adapt charge delivery to actual operational needs
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution ensures the boost capacitor maintains sufficient charge to facilitate the operation of high side switches, preventing voltage depletion and ensuring reliable circuit operation by selectively managing charging and discharging currents.
Implementation Method 1
a capacitor is coupled to an output of a power switch of a voltage regulator. Charge delivery circuitry is coupled to the capacitor and configured to provide a charging current to the capacitor
Implementation Method 2
the charge control circuitry includes a comparator coupled to sense a differential voltage across the capacitor. The comparator is configured to selectively allow the providing of the charging current responsive to the sensed differential voltage crossing a threshold voltage
Implementation Method 3
the charge control circuitry includes an amplifier coupled to sense a voltage across the capacitor. The amplifier is operatively coupled as part of a feedback loop to provide a feedback signal to drive the capacitor voltage to a reference voltage
Data Source
AI summary
Disclosed are devices, apparatus, circuitry, components, mechanisms, modules, units, systems, and processes for controlling a power switch of a voltage regulator. A capacitor is coupled to an output of the power switch. Charge delivery circuitry is coupled to the capacitor and configured to provide a charging current to the capacitor. Charge control circuitry can be coupled to the charge delivery circuitry and configured to selectively allow the providing of the charging current to the capacitor.