Charge Pump Failure Protection via Current Limiting
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Solution Overview
Problem
In electrical systems, particularly in applications like class D audio amplifiers, the power supply voltage is often insufficient to drive high-side transistors, and space constraints or declining battery voltage can prevent the use of optimal battery cells, necessitating a solution to generate a higher voltage efficiently.
Innovation Solution
A charge pump device that uses a capacitive voltage conversion method, combining a pumping capacitor charged to the battery voltage with an internally generated voltage to produce a higher output voltage, while incorporating current-limiting and start-up protection circuits to prevent damage from short-circuit conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a charge pump is used to generate higher voltage, then the power supply capability is improved, but the risk of short-circuit damage increases
Solution Approach 1:
The patent applies preliminary action by implementing a start-up detection circuit that activates protection mechanisms before the charge pump begins operation. The circuit detects startup conditions and enables current limiting protection in advance, preventing short-circuit damage before it can occur during high-power operation.
Solution Approach 2:
The patent uses an intermediary approach by introducing a detection circuit as a mediator between the charge pump and the power supply. This intermediary circuit monitors the startup phase and controls the enabling of protection mechanisms, allowing the system to safely transition from low-power startup to high-power operation without direct exposure to short-circuit risks.
2Reliability
If current limiting protection is implemented, then reliability against short-circuits is improved, but device complexity increases
Solution Approach 1:
The patent merges the detection and protection functions into a single integrated start-up detection circuit. By combining the startup detection, current limiting control, and protection enabling functions into one unified circuit block, the patent reduces overall device complexity while maintaining comprehensive short-circuit protection.
Solution Approach 2:
The start-up detection circuit serves multiple functions simultaneously: it detects startup conditions, controls current limiting, and enables protection mechanisms. This multi-functional design reduces the need for separate dedicated circuits for each function, thereby reducing overall device complexity while maintaining reliable protection.
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 charge pump effectively generates a voltage higher than the power supply voltage, doubling the voltage swing and power delivery, while ensuring reliability and safety through current-limiting and fault detection mechanisms, suitable for automotive and handheld applications.
Implementation Method 1
A charge pump device that uses a capacitive voltage conversion method, combining a pumping capacitor charged to the battery voltage with an internally generated voltage to produce a higher output voltage
Data Source
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Figure 3A~3B
AI summary
Disclosed is a charge pump protection device including a power supply voltage, a charge pump to produce an output voltage higher than the power supply voltage, the charge pump including, a pumping capacitor to store voltage during a charging state and to discharge the voltage during a pumping state thereof, a plurality of switches to regulate the charging and pumping states, a charge pump capacitor to store the output voltage, and at least one current limiter in series with at least one of the plurality of switches to limit current and prevent an electrical failure of the charge pump.