DC-DC Converter DC Offset Correction for Mode Transition Glitches
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Solution Overview
Problem
Conventional dual-mode DC-DC converters experience a DC voltage anomaly when switching between PWM and PFM modes due to differences in initial conditions, leading to inaccuracies in output voltage regulation.
Innovation Solution
A DC voltage offset correction mechanism is integrated into the PWM mode error amplifier, which compensates for any DC voltage offsets by injecting a correction current into the voltage regulation path, ensuring seamless transitions between modes by setting initial conditions to zero and storing correction values for subsequent mode changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the converter transitions between PWM and PFM modes using conventional dual-mode DC-DC converter architecture, then the converter can operate in both PWM and PFM modes, but a DC voltage anomaly occurs at mode transition due to differences in initial conditions
Solution Approach 1:
The patent applies preliminary action by pre-setting the initial conditions of the PWM error amplifier before mode transition. Specifically, the initial conditions are set to match the final conditions of PFM mode, ensuring a seamless transition without DC voltage anomalies. This is achieved by controlling the PWM error amplifier's initial state in advance of the mode switch.
2Measurement precision
If a DC voltage offset correction mechanism is added to the PWM error amplifier, then DC offset anomalies are compensated for, but the device complexity increases
Solution Approach 1:
The patent implements self-service by enabling the PWM error amplifier to automatically compensate for its own DC offset errors. The error amplifier includes circuitry that detects and corrects its own DC voltage offsets without requiring external intervention or additional complex control systems, thereby improving precision while limiting complexity growth.
Solution Approach 2:
The patent uses feedback by implementing a DC offset correction mechanism that continuously monitors the output voltage and adjusts the error amplifier's operation accordingly. The correction is based on feedback from the actual output voltage compared to the expected voltage, allowing dynamic compensation for DC offsets and improving regulation accuracy.
Data Source
AI summary
To prevent a voltage glitch in the regulated DC output voltage of a PWM/PFM DC-DC converter when switching between PFM and PMW modes, the error amplifier of the converter's PWM regulation path is provided with a DC voltage offset correction mechanism. This mechanism “zeros-out” DC voltage offsets that may be present in the voltage regulation path, thereby enabling the error amplifier to accurately regulate the converter's output voltage. When the converter transitions between PFM and PWM modes, the DC offset correction mechanism establishes initial conditions of the error amplifier that effectively ensure that the converter's regulated output voltage at the beginning of a new “switched-to” PWM mode cycle is DC offset-free.