Reverse Current Protection Circuit for Switch Circuits
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Solution Overview
Problem
Conventional reverse current protection circuits in switch circuits fail to provide timely and effective protection against reverse currents, leading to unstable output voltages during start-up and load changes, and potential damage to the device.
Innovation Solution
A reverse current protection circuit with a reverse current control circuit that disconnects the output terminal from the input terminal when the output voltage exceeds a predetermined voltage, and an enable/disable circuit that temporarily disables the reverse current control circuit to prevent overshoot voltage issues, coupled with a voltage regulator to stabilize the output voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the voltage reference is set equal to the input terminal voltage for reverse current protection, then reverse current protection is provided, but the protection is not timely and output voltage becomes unstable during start-up and load changes
Solution Approach 1:
The patent applies preliminary action by setting the voltage reference lower than the input terminal voltage before reverse current conditions occur. This allows the reverse current protection circuit to activate in advance, disconnecting the output terminal before reverse current damage can occur. The enable/disable circuit further refines this by temporarily disabling protection during known safe periods (start-up and load changes) before re-enabling it when conditions are favorable.
2Reliability
If the voltage reference is set lower than the input terminal voltage to provide timely protection, then reverse current protection is timely, but output voltage becomes unstable during start-up and load changes
Solution Approach 1:
The patent applies dynamics by making the voltage reference adjustable rather than fixed. The enable/disable circuit dynamically modifies the voltage reference based on operating conditions: during start-up and load changes, the reference is temporarily raised to prevent false disconnection, and after a predetermined time period, it is lowered again to provide timely reverse current protection. This dynamic adjustment resolves the contradiction between timely protection and voltage stability.
3Reliability
If the reverse current control circuit disconnects the output terminal during reverse current conditions, then reverse current damage is prevented, but overshoot voltage is pulled down causing repeated disconnection and voltage instability
Solution Approach 1:
The patent applies periodic action through the enable/disable circuit, which temporarily disables the reverse current control circuit for a predetermined time period after disconnection occurs. This periodic disabling prevents the oscillating disconnection-reconnection cycle by maintaining the disconnected state during the time when overshoot voltage would otherwise cause repeated triggering. After the predetermined period, the circuit is re-enabled to resume reverse current protection when conditions are stable.
Data Source
AI summary
A reverse current protection circuit for a switch circuit includes a reverse current control circuit and an enable/disable circuit coupled to the reverse current control circuit. The reverse current control circuit is coupled to an input terminal and an output terminal of the switch circuit, and disconnects the output terminal of the switch circuit from the input terminal of the switch circuit when an output voltage of the switch circuit is higher than a first predetermined voltage. The enable/disable circuit disables the reverse current control circuit for a first predetermined time period when the output voltage of the switch circuit becomes lower than the first predetermined voltage after being higher than the first predetermined voltage, and enables the reverse current control circuit after the first predetermined time period.