Multiplexed Pin Start-Up Circuit for Power Regulator Delay Control
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Solution Overview
Problem
Existing start-up circuits for power regulators face challenges in accurately controlling delay time and protecting against inrush currents, leading to potential damage and inefficiencies during the power-on process due to the use of discrete components and lack of current-limiting protection.
Innovation Solution
A start-up circuit utilizing a multiplexed pin of an integrated chip with an external RC delay circuit for controlled delay time and current-limiting protection, where the voltage at the multiplexed pin increases continuously with a fixed rising slope, allowing for shared pin usage for both functions, thereby reducing component count and preventing output voltage overshoot.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a starting switch is used to reduce standby loss and regulate start-up delay time, then power management and sequencing are improved, but inrush current protection is insufficient leading to potential damage
Solution Approach 1:
The patent introduces an intermediary protection circuit between the power supply and the starting switch that detects inrush current conditions and intervenes to prevent damage. This intermediary mechanism monitors the start-up process and activates protection measures when inrush current exceeds safe thresholds, thereby resolving the contradiction between enabling start-up functionality and preventing inrush current damage.
Solution Approach 2:
The patent implements preliminary protective measures by pre-configuring current limiting circuits and protection mechanisms before the inrush current event occurs. The system prepares protection thresholds and response mechanisms in advance, so when start-up begins, the protection is already in place to prevent damage while allowing controlled power sequencing.
2Adaptability or versatility
If discrete components are used for delay time control, then flexibility is improved, but device complexity and component count increase
Solution Approach 1:
The patent combines multiple discrete delay control components into an integrated delay control circuit that provides the same flexibility through a unified structure. The integrated circuit internally implements multiple delay thresholds and control mechanisms that previously required separate discrete components, thereby reducing overall device complexity while maintaining adaptability for different delay time requirements.
Solution Approach 2:
The patent designs a universal delay control module that can operate with different time constants and configurations through a single integrated circuit. This multi-functional module replaces multiple discrete components by providing adjustable delay characteristics through internal programmable or selectable parameters, achieving the same versatility with reduced component count.
3Stability of the object's composition
If filter capacitor voltage is zero at start-up, then capacitor charging is necessary, but heavy inrush current occurs causing abnormal switch operation
Solution Approach 1:
The patent converts the harmful inrush current phenomenon into a beneficial controlled charging process. By implementing current-limiting circuits and soft-start mechanisms, the previously damaging instantaneous surge is transformed into a controlled, gradual capacitor charging process that maintains power voltage stability while preventing abnormal switch operation. The energy that would cause harm is redirected through protection circuits to achieve stable start-up.
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 provides accurate control over delay time and current limiting, reducing the risk of damage and ensuring smooth power-on processes by using a shared multiplexed pin for both functions, resulting in a more efficient and reliable start-up circuit.
Implementation Method 1
a delay circuit having a first resistor and a first capacitor, where the first capacitor is coupled between ground and a common node
Implementation Method 2
The voltage at the multiplexed pin can increase continuously with a fixed rising slope that is determined by input current flowing through the multiplexed pin
Data Source
AI summary
Methods and circuits related to power regulator start-up are disclosed. In one embodiment, a start-up circuit can include: (i) a delay circuit having a resistor and a capacitor, where the capacitor is coupled between ground and a common node; and (ii) a control chip that receives a reference voltage, and includes an input pin coupled to an input source, an output pin supplying power for a device, and a multiplexed pin coupled to the resistor at the common node to receive an enable signal. The start-up circuit outputs an electrical signal at the output pin based on a comparison of a voltage at the multiplexed pin against the reference voltage, and after a delay time determined by the capacitor and the reference voltage. The voltage at the multiplexed pin can increase continuously with a rising slope determined by input current flowing through the multiplexed pin during a start-up process.