Electronic Switch Drive Circuit Slew Rate Control
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Solution Overview
Problem
Conventional drive circuits for electrical loads face challenges in integrating passive components like resistors or capacitors, which increase manufacturing costs and fail to effectively limit the slew rate of voltage across loads, leading to EMI issues.
Innovation Solution
A method that involves an electronic switch with a drive terminal, where the switch is cycled between operation states, and a drive profile is generated based on a measured switching profile compared to a reference profile, using multiple drive parameters at different times to control the switching speed and reduce slew rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If passive components (resistors or capacitors) are used to filter the drive voltage and control switching behavior, then the switching behavior can be controlled, but the manufacturing costs increase and integration into the semiconductor chip becomes difficult
Solution Approach 1:
The invention extracts the filtering function from separate passive components and integrates it into the semiconductor chip itself through a filter unit that is part of the drive circuit. This eliminates the need for external resistors or capacitors while maintaining the switching control functionality.
Solution Approach 2:
The drive circuit is merged with the semiconductor chip, combining the electronic switch and filter unit into a single integrated device. This integration eliminates external passive components, reduces manufacturing costs, and simplifies the overall system architecture.
2Productivity
If the electronic switch switches fast from off-state to on-state, then the switching efficiency is improved, but the slew rate of voltage across the load increases causing voltage peaks and EMI
Solution Approach 1:
The drive circuit dynamically adjusts the switching speed of the electronic switch by varying the drive voltage over time. The filter unit shapes the drive voltage waveform to achieve optimal switching performance while controlling the slew rate, balancing switching efficiency with EMI reduction.
Solution Approach 2:
The measured switching profile is compared with a reference profile to generate a drive profile that is stored and used to drive the electronic switch in subsequent switching cycles. This feedback mechanism optimizes switching performance while controlling voltage slew rate and EMI.
3Object-affected harmful factors
If the slew rate of voltage across the load is limited to reduce EMI, then EMI is reduced, but the switching speed of the electronic switch must be controlled
Solution Approach 1:
The drive circuit applies periodic drive voltage waveforms with controlled rise and fall times. The filter unit shapes these periodic waveforms to limit the voltage slew rate across the load, reducing EMI while maintaining adequate switching speed through optimized waveform characteristics.
Data Source
AI summary
An electronic switch includes a load path connected in series with the load and a drive terminal for receiving a drive signal. The electronic switch is operable to switch between a first operation state and a second operation state dependent on the drive signal. In a first switching cycle, the electronic switch is switched from the first operation state to the second operation state and a voltage across the load is evaluated during the first switching cycle in order to obtain a measured switching profile. The measured switching profile is compared with a reference profile. A drive profile dependent on the comparison is provided. The drive profile is used to drive the electronic switch in a second switching cycle after the first switching cycle. At least two drive parameters are used at different times in the at least one second switching cycle to drive the electronic switch.