Low Power Start-Up Circuit Using Zener Diode and Dynamic Switching
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Solution Overview
Problem
Conventional start-up circuits in power converters consume high power and occupy significant space due to the use of Low-Dropout (LDO) regulators and bandgap blocks, which hinder the development of energy-efficient and compact power converters.
Innovation Solution
A start-up circuit utilizing a Zener diode to provide a reference voltage, coupled with a coarse current source and a bandgap circuit to reduce power consumption and size, where the Zener diode generates a first reference voltage for initial start-up and is replaced by a more stable bandgap voltage for accurate undervoltage lockout detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional LDO regulators and bandgap blocks are used in the start-up circuit, then the circuit can perform voltage regulation and reference voltage generation, but the power consumption and circuit size increase significantly
Solution Approach 1:
The patent extracts and removes the LDO regulator from the start-up circuit, replacing it with a simpler voltage detection mechanism that uses a voltage divider and comparator. This extraction eliminates the high power consumption associated with LDO regulators while retaining the essential function of voltage monitoring and control.
Solution Approach 2:
The patent employs simple resistive voltage dividers and basic comparators instead of complex, power-hungry LDO regulators. These simpler components consume minimal power and are sufficient for the start-up phase voltage detection function, aligning with the principle of using simpler, lower-cost components when full regulation capability is not needed.
2Reliability
If conventional LDO regulators and bandgap blocks are used in the start-up circuit, then the circuit can perform voltage regulation and reference voltage generation, but the circuit area occupied increases
Solution Approach 1:
The patent removes the LDO regulator and replaces it with a compact voltage divider network and comparator arrangement. This extraction significantly reduces the circuit area while maintaining the core functionality of voltage monitoring and control during start-up.
Solution Approach 2:
The patent uses a simplified voltage detection mechanism that copies the essential function of the LDO regulator without requiring its full complexity. The voltage divider and comparator provide sufficient voltage monitoring capability for start-up operations with minimal area occupation.
3Use of energy by stationary object
If a Zener diode is used to provide reference voltage, then power consumption and size are reduced, but voltage stability may be compromised compared to bandgap circuits
Solution Approach 1:
The patent dynamically switches between different reference voltage sources during operation. During normal operation, it uses the low-power Zener diode reference, and during undervoltage lockout detection, it transitions to using the more stable bandgap circuit reference. This dynamic switching optimizes both power consumption and voltage stability according to operational requirements.
Solution Approach 2:
The patent changes the reference voltage parameter based on operational mode. It uses the Zener diode's breakdown voltage characteristic for normal operation and switches to the bandgap circuit's temperature-compensated reference voltage when undervoltage lockout detection is required, thereby adapting the voltage stability parameter to match 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
The solution significantly reduces power consumption and size, achieving lower energy loss and more accurate undervoltage lockout detection, aligning with the requirements of modern energy-efficient power converters.
Implementation Method 1
a first reference voltage generated at a Zener diode is provided to a comparator
Implementation Method 2
a second reference voltage generated at a bandgap circuit is provided to the comparator
Data Source
AI summary
A start-up circuit in a switch-mode power converter that employs a Zener diode to provide a reference voltage to reduce the power consumption and the size of the start-up circuit. The start-up circuit also includes a coarse current source and a coarse reference voltage signal generator for producing current and reference voltage for initial startup operation of a bandgap circuit. The reference signal and current from coarse current source and the reference voltage signal generator are subject to large process, voltage and temperature (PVT) variations or susceptible to noise from the power supply, and hence, these signals are used temporarily during start-up and replaced with signals from higher performance components. After bandgap circuit becomes operational, the start-up receives voltage reference signal from the bandgap circuit to more accurately detect undervoltage lockout conditions.