Interlock Logic Circuit for Multi-Port Charging Current Control
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Solution Overview
Problem
Multi-port charging systems, such as USB charging systems, face challenges in managing current distribution to prevent simultaneous overloads across multiple ports, which can lead to brownouts if not properly controlled, as existing systems lack effective interlocking mechanisms to manage current limits and prevent simultaneous overload conditions.
Innovation Solution
The implementation of an interlocking control technique between port circuits, where one port can support an overload for a defined time interval while limiting current to other ports, using a two-level current limit scheme and interlock logic to manage current distribution and prevent simultaneous overloads, thereby ensuring stable power supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple ports are allowed to draw current simultaneously without interlocking control, then each port can operate independently, but simultaneous overloads can occur causing brownouts
Solution Approach 1:
An interlock logic circuit is introduced as an intermediary between multiple port power circuits. This circuit receives overload signals from any port and generates interlock signals to other ports, mediating the current distribution to prevent simultaneous overloads while allowing independent operation. The interlock logic acts as a coordinator that maintains system stability without restricting individual port functionality.
2Reliability
If current limit is enforced strictly on all ports simultaneously, then system protection is improved, but one port cannot support overload when another port needs high current
Solution Approach 1:
The current limit settings are made dynamic rather than fixed. When an overload condition is detected on one port, the interlock logic dynamically adjusts current limits on other ports temporarily. This allows the system to adapt current distribution in real-time based on actual load conditions, enabling one port to support overload when another port requires high current, while maintaining overall system protection.
3Adaptability or versatility
If interlock logic delays providing current limit signal, then one port can support overload for defined time interval, but response time to prevent overload is increased
Solution Approach 1:
The interlock logic circuit is pre-configured with delay circuitry that provides a defined time interval before asserting current limit signals. This preliminary timing mechanism allows ports to tolerate brief overload conditions without triggering immediate protection, while still responding quickly enough to prevent sustained overloads. The delay is built into the logic circuit design to provide controlled tolerance without sacrificing overall protection speed.
Data Source
AI summary
In a described example, a circuit includes a port power path circuit having a power input and a first overload output. An interlock logic circuit has an interlock input, a current limit input and a current limit set output. The current limit input is coupled to the first overload output, and the interlock input is adapted to be coupled to a second overload output of a second port power circuit. The interlock logic circuit is configured to delay providing an output signal to the current limit set output responsive to an overload signal at the current limit input.