Digital Isolator Clamping Circuit for Common-Mode Transients
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Solution Overview
Problem
Existing digital isolator circuits are susceptible to damage from common-mode transient interference due to the use of high-speed low-voltage devices, which are vulnerable to high-voltage signals generated by interference.
Innovation Solution
A common-mode transient suppression protection circuit is introduced, featuring a linear voltage regulator structure with a power supply clamp and a drive circuit with a clamping module, which protects low-voltage devices from high-voltage signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high-speed low-voltage devices are used in the drive circuit, then the switching speed and data transmission rate are improved, but the circuit becomes susceptible to damage from common-mode transient interference
Solution Approach 1:
The patent applies beforehand cushioning by introducing clamping modules (first and second clamping modules) that are pre-configured to activate when voltage exceeds safe thresholds. These modules provide protective action before damage can occur to the low-voltage devices, allowing the system to maintain high-speed operation while having automatic protection mechanisms in place against common-mode transient interference.
Solution Approach 2:
The patent uses intermediary elements (clamping modules with reference voltage nodes) that mediate between the high-voltage interference environment and the low-voltage sensitive devices. The clamping modules act as intermediaries that can absorb or redirect transient voltage spikes, protecting the core low-voltage drive circuit while allowing it to operate at high speeds without direct exposure to interference.
2Reliability
If common-mode transient suppression protection circuits are added, then the reliability against interference is improved, but the device complexity increases
Solution Approach 1:
The patent merges the protection function into the existing drive circuit structure by integrating clamping modules at critical nodes (gate-source and gate-drain connections of MOS transistors). Rather than adding completely separate protection circuits, the clamping functionality is combined with the existing power supply and signal routing, reducing overall system complexity while maintaining reliable protection against common-mode transients.
Data Source
AI summary
The present invention provides a common-mode transient suppression protection circuit for a digital isolator, including a modulation circuit, a demodulation circuit and an isolation capacitor connected between the modulation circuit and the demodulation circuit. The modulation circuit includes a modulation circuit front-end and a drive circuit, which are connected in sequence, and a clamping module is arranged in the drive circuit. The protection circuit further includes a linear voltage regulator structure connected with the drive circuit, and a power supply clamp is arranged in the linear voltage regulator structure. By providing the linear voltage regulator structure having the power supply clamp and the drive circuit having the clamping module in the protection circuit, low-voltage devices in the drive circuit can be protected from being damaged by high-voltage signals generated by common-mode transient interference.