High-Side MOSFET Switch Drive for Rapid Charge Pump Turn-Off
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Solution Overview
Problem
High-side electronic switches in automotive power supply systems experience significant switching delays due to the use of charge pumps, leading to voltage drops in secondary power sub-systems when the starter is actuated, necessitating a rapid switching solution to maintain voltage stability.
Innovation Solution
An electronic circuit with a drive circuit that includes a second drive unit with a further electronic switch to rapidly discharge the internal capacitances of the MOSFET, allowing for rapid switching off of the high-side switch, reducing switching delay and maintaining voltage stability in the secondary power sub-system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a charge pump is used to drive a high-side electronic switch, then the switch can be controlled to connect or disconnect power supply sub-systems, but the switching delay becomes relatively long (several 10 microseconds)
Solution Approach 1:
The drive circuit is segmented into two independent drive units: a first drive unit with a charge pump for normal switching operations, and a second drive unit with a further electronic switch for rapid switching. Each drive unit can independently control the main electronic switch, allowing the system to select the appropriate drive unit based on operational requirements.
Solution Approach 2:
The system dynamically switches between two different driving mechanisms depending on the situation. During normal operation, the charge pump provides controlled switching. When rapid response is needed (e.g., when starter actuation causes voltage drop), the second drive unit with the further electronic switch takes over to provide ultra-fast switching response.
2Reliability
If the electronic switch is opened to prevent voltage drop in the second sub-system, then the battery in the second circuit can supply the loads, but the voltage may significantly drop between detection and switching due to delay time
Solution Approach 1:
The second drive unit is pre-configured and ready to immediately discharge the internal capacitances of the MOSFET when triggered. This preliminary preparation allows the circuit to bypass the slow charge pump discharge process and directly force the MOSFET into cutoff, achieving rapid response to voltage drop conditions.
Solution Approach 2:
When rapid switching is required, the second drive unit skips the normal charge pump discharge process and directly discharges the internal capacitances through an alternative path. This rushing through of the capacitance discharge step eliminates the bottleneck that causes switching delay.
3Ease of operation
If a charge pump is used to drive the high-side switch, then the switch can be turned on and off, but the internal capacitances of the MOSFET discharge slowly causing delayed switching off
Solution Approach 1:
The second drive unit acts as an intermediary mechanism that provides an alternative discharge path for the internal capacitances of the MOSFET. When activated, this intermediary circuit bypasses the slow charge pump and directly discharges the capacitances through the further electronic switch, enabling rapid turn-off.
Solution Approach 2:
The system changes the discharge parameter of the internal capacitances by switching between two different discharge paths: the normal charge pump discharge path (slow) and the second drive unit discharge path (fast). This parameter change allows the system to achieve both controlled operation and rapid switching as needed.
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 solution effectively reduces switching delay, preventing significant voltage drops in the secondary power sub-system by rapidly disconnecting the high-side switch when the starter is actuated, ensuring continuous operation of loads connected to the secondary battery.
Implementation Method 1
The first drive unit 3 is configured to generate a drive signal SDRV and a charge pump potential Vcp
Implementation Method 2
a second drive unit 5 coupled between the second input terminal 23 and the output terminal 21, wherein the second drive unit 5 further includes a further electronic switch 6 coupled between the output terminal 21 and a terminal for a reference potential
Data Source
AI summary
An electronic circuit includes an electronic switch with a control terminal and a load path between a first and a second load terminal, and a drive circuit with an output terminal coupled to the control terminal of the electronic switch. The drive circuit includes a first input terminal and a second input terminal, a first drive unit coupled between the first input terminal and the output terminal and including a charge pump and drive unit, and a second drive unit coupled between the second input terminal and the output terminal and including a further electronic switch coupled between the output terminal and a terminal for a reference potential.