Series Regulator Noise Buffering in Portable DC-DC Power Supplies
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Solution Overview
Problem
Conventional switching DC-DC converters in portable devices suffer from switching noise that adversely affects other circuit blocks, leading to reliability issues and reduced performance, and existing filter circuits increase power loss, especially under heavy loads.
Innovation Solution
A power supply unit comprising a series regulator and a switching power supply circuit, where the series regulator buffers the input voltage to attenuate switching noise, maintaining a constant voltage difference and using an RC filter to reduce noise impact, while the switching power supply circuit adjusts output voltage based on load conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a switching DC-DC converter is used to convert battery voltage to output voltage, then power conversion efficiency is improved, but switching noise is generated that adversely affects other circuit blocks
Solution Approach 1:
A series regulator is introduced as an intermediary component between the battery and the switching DC-DC converter. The series regulator buffers the input voltage and attenuates switching noise before it reaches other circuit blocks, while allowing the switching converter to maintain its high efficiency operation. This mediator approach resolves the contradiction by isolating the noise-generating switching operation from sensitive circuits.
Solution Approach 2:
The power supply system is segmented into two independent stages: a series regulator stage for noise filtering and voltage buffering, and a switching DC-DC converter stage for efficient voltage conversion. This segmentation allows each stage to optimize its function independently - the series regulator handles noise suppression while the switching converter maintains high efficiency.
2Object-affected harmful factors
If a filter circuit consisting of resistor and capacitor is used to reduce switching noise, then switching noise influence is reduced, but power loss increases especially under heavy load
Solution Approach 1:
The series regulator dynamically adjusts its output impedance based on operating conditions. By controlling the series pass transistor, the regulator optimizes the balance between noise filtering capability and power loss, maintaining low power consumption under heavy load conditions while still effectively attenuating switching noise.
Solution Approach 2:
The series regulator changes its operating parameters (voltage drop, current control) to optimize performance across different load conditions. By dynamically adjusting these parameters, it maintains effective noise filtering while minimizing power loss, especially under heavy load where traditional RC filters would consume excessive power.
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
The solution effectively reduces switching noise on the input voltage, minimizing its adverse effects on circuit blocks and maintaining high power conversion efficiency by varying resistance with load conditions, thus stabilizing the operation of portable devices.
Implementation Method 1
a series regulator receiving an input source voltage, and adapted to output a first output voltage that is lower than the input source voltage by a predetermined voltage
Implementation Method 2
If this switching noise is superimposed on the source voltage, the superposed noise will become a cause of adverse influence on other circuit blocks
Implementation Method 3
a switching power supply circuit supplied with the first output voltage and adapted to output a second output voltage
Data Source
AI summary
An input source voltage is supplied from a battery for example to a switching power supply circuit such as a switching DC-DC converter via a series regulator for stepping down the input source voltage by a constant voltage. The series regulator serves as a buffer having a variable resistance to reduce the switching noise generated by the switching power supply circuit, thereby reducing the switching noise in the input source voltage and in turn reducing adverse influence of the noise on other circuit blocks that operate at the input source voltage.