High-Side IPS Charge Pump Voltage Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-side load driving circuits, such as those used in automobiles, face issues when the power supply voltage fluctuates, as they can result in abnormally high voltages being applied across capacitors, potentially exceeding the rated voltage, especially when using n-channel MOSFETs and charge pump circuits.
Innovation Solution
A load driving circuit with an n-channel transistor and a charge pump circuit that includes an oscillating unit, switching unit, and charge-up unit, where the switching unit blocks oscillation signals during power-off states, preventing excessive voltage fluctuations from affecting the capacitors, and using an internal power supply referenced to the power supply voltage to generate a boosted gate voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the output voltage of the charge pump circuit is fixed to a voltage obtained by resistively dividing the voltage of the power supply VDH, then the circuit is simple to implement, but the voltages applied across both ends of the capacitors can exceed the rated voltage when the power supply voltage fluctuates significantly
Solution Approach 1:
The patent changes the parameter of voltage reference from the fluctuating power supply voltage VDH to a stable internal power supply voltage VDD. By referencing the charge pump output to VDD instead of VDH, the capacitor voltages are decoupled from power supply fluctuations, ensuring they remain within rated limits while maintaining circuit simplicity.
2Power
If an n-channel MOSFET is used for the semiconductor switch, then the on-resistance per unit area is lower, but a gate voltage higher than the supply voltage must be applied, requiring a charge pump circuit that becomes vulnerable to voltage fluctuations
Solution Approach 1:
The patent introduces an internal power supply VDD as an intermediary between the power supply VDH and the charge pump circuit. This intermediary provides a stable reference voltage that mediates the charge pump operation, allowing the n-channel MOSFET to be driven reliably while isolating the charge pump capacitors from the effects of power supply fluctuations.
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
This configuration ensures that capacitors are not affected by significant fluctuations in the supply voltage, preventing abnormally high voltages from being applied across their ends, thus protecting the circuit components.
Implementation Method 1
a charge pump circuit that is powered by an internal power supply and that references a power supply voltage, the charge pump circuit generating a gate voltage that is boosted higher than the power supply voltage
Data Source
AI summary
A charge pump circuit in a high-side intelligent power switch includes a switching unit between an oscillating unit and a charge-up unit. When the high-side IPS serving as a load driving circuit is in a standby state, a MOSFET switches ON and the switching unit blocks the transmission of signals output from the oscillating unit to the charge-up unit. This prevents a power supply voltage, which can potentially fluctuate, from being applied to capacitors of the charge-up unit via body diodes of inverter circuits in the switching unit while the high-side IPS is in the standby state, thereby suitably protecting the capacitors.