Bi-Polar Load Regulation Timing in Switching Voltage Regulators
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Solution Overview
Problem
Existing voltage regulators face inefficiencies and inaccuracies due to voltage ripples and DC offsets caused by load polarity changes, particularly in switched DC-DC converters with bi-polar load currents.
Innovation Solution
A voltage regulator system with a current source circuit and control circuit that delays the enablement of a negative current regulator until after the voltage regulator is disabled and the output node voltage exceeds a predetermined level, ensuring full charge transfer before drawing current away to mitigate voltage ripples and offsets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a current source circuit draws current away from the output node to regulate bi-polar load currents, then load regulation capability is improved, but voltage ripples and DC offsets increase
Solution Approach 1:
The control circuit delays enabling the current source circuit until after the voltage regulator is disabled and the output voltage exceeds a predetermined threshold. This preliminary timing action ensures the output capacitor is fully charged before the current source begins drawing current, preventing voltage ripples and DC offsets while maintaining bi-polar load regulation capability
2Loss of energy
If the voltage regulator is disabled to improve power efficiency, then power conversion efficiency is improved, but output voltage stability deteriorates
Solution Approach 1:
Before disabling the voltage regulator, the control circuit ensures the output voltage exceeds a predetermined threshold, indicating the output capacitor is fully charged. This preliminary charging action allows the regulator to be disabled for power efficiency while maintaining output voltage stability through the charged capacitor
Solution Approach 2:
The output capacitor acts as an intermediary energy storage element that maintains output voltage stability during periods when the voltage regulator is disabled. The capacitor bridges the gap between regulator shutdown and potential re-enablement, preventing voltage fluctuations
3Speed
If the negative current regulator is enabled immediately to respond to load changes, then response speed is improved, but voltage fluctuations increase
Solution Approach 1:
The control circuit performs a preliminary check to ensure the output voltage exceeds a predetermined threshold before enabling the negative current regulator. This preliminary verification ensures the output capacitor is charged, allowing immediate regulator response without causing voltage fluctuations
Solution Approach 2:
The control circuit continuously monitors the output voltage and uses this feedback to determine the appropriate timing for enabling the negative current regulator. The feedback mechanism ensures the regulator is only enabled when output voltage conditions are favorable, preventing fluctuations while maintaining fast response
Data Source
AI summary
The present disclosure describes a system with a voltage regulator, a current source circuit, and a control circuit. The voltage regulator has an output node and is configured to provide a supply voltage at the output node. The current source circuit is configured to draw current away from the voltage regulator's output node. And, the control circuit is configured to delay enabling the current source circuit in response to a voltage at the voltage regulator's output node being above a predetermined voltage level and the voltage regulator being disabled. With this arrangement, a voltage ripple at the voltage regulator's output node can be reduced in the presence of a bi-polar load current, which can be advantageous in voltage regulator designs (e.g., in DC-DC converters employing a Pulse Frequency Modulation scheme).