Under-Voltage Lockout Circuit for Connector Transient Current Protection
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Solution Overview
Problem
During the extraction of a connector insert from a connector receptacle, undesirable transient currents can occur, potentially damaging electrical components due to variations in VBUS power and ground contact positions, leading to improper disconnection and current flow through ESD diodes.
Innovation Solution
The implementation of under-voltage and under-current lockout circuits that detect drops in VBUS supply or current and provide a high impedance in series with the ESD diode to prevent damage, using threshold settings relative to recent averages and hysteresis to manage transient conditions, and employing switches or variable impedance to control current flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If VBUS power and ground contacts are placed at the same distance from the front of the connector receptacle tongue, then simultaneous disconnection occurs during extraction, but manufacturing variations in contact lengths and placements cause improper disconnection sequences leading to transient currents
Solution Approach 1:
The patent applies preliminary action by implementing an under-voltage lockout circuit that proactively detects the disconnection state and preemptively activates a high-impedance state in the charging regulator before transient currents can damage the ESD diode. This advance preparation prevents the harmful effect rather than reacting to it after occurrence.
Solution Approach 2:
The under-voltage lockout circuit serves as an intermediary between the connector disconnection event and the charging regulator/ESD diode. It monitors the VBUS voltage and ground connection status, and when improper disconnection is detected, it mediates by activating the high-impedance state to block harmful transient currents from reaching the sensitive components.
2Reliability
If ground contacts are disconnected before VBUS power contacts during connector extraction, then proper disconnection sequence is maintained, but manufacturing variations cause VBUS to remain connected after ground disconnection creating current pathways
Solution Approach 1:
The under-voltage lockout circuit implements feedback by continuously monitoring the VBUS voltage level and ground connection status. When it detects that VBUS remains connected while ground has disconnected (improper sequence), the feedback signal triggers the charging regulator to enter a high-impedance state, blocking the harmful transient current pathway through the ESD diode.
Solution Approach 2:
The patent applies preliminary anti-action by having the under-voltage lockout circuit detect the improper disconnection sequence and preemptively activate the high-impedance state in the charging regulator. This counter-action occurs before the transient current can flow through and damage the ESD diode, effectively preventing the harmful effect in advance.
3Reliability
If ESD diode is used to protect against transient currents, then component protection is provided, but the diode itself can be damaged by high currents during improper disconnection sequences
Solution Approach 1:
The under-voltage lockout circuit applies preliminary action by detecting improper disconnection sequences and preemptively activating the high-impedance state in the charging regulator before transient currents can exceed the ESD diode's current capacity. This advance protection preserves the ESD diode's integrity rather than relying on it to withstand damaging currents.
Solution Approach 2:
The charging regulator in high-impedance state serves as an intermediary protective element between the VBUS power supply and the ESD diode. When improper disconnection is detected, this intermediary blocks the harmful current pathway, protecting the ESD diode from exceeding its current capacity while still allowing the ESD diode to function as a protection device under normal conditions.
4Adaptability or versatility
If threshold voltage is set to track VBUS voltage changes, then adaptability to different VBUS levels is achieved, but the threshold may never be reached during disconnection preventing lockout activation
Solution Approach 1:
The patent applies partial action by setting the threshold voltage to track only a portion of the VBUS voltage changes (using a tracking ratio less than 1:1). This partial tracking maintains adaptability to different VBUS levels while ensuring that during disconnection when VBUS drops, the threshold remains sufficiently high to be reached and activate the lockout function reliably.
Solution Approach 2:
The under-voltage lockout circuit implements parameter changes by dynamically adjusting the threshold voltage based on the tracked average VBUS level. This parameter adaptation allows the system to accommodate different VBUS voltage levels while maintaining reliable lockout activation during disconnection events, as the threshold responds to gradual changes rather than immediate drops.
Data Source
AI summary
Circuits, methods, and apparatus that prevent or limit undesirable transient currents that may occur during a connector insert extraction and may damage electrical components connected to the connector receptacle.