When conducting the lightning surge immunity test, waveform verification is a crucial step to ensure the accuracy of the test. As a professional TVS (transient voltage suppression diode) device manufacturer, Leimao Electronics has always been concerned about the compatibility of devices and waveforms in surge tests. The following, in combination with industry standards, Leimao EMC expert will explain the key points of lightning surge test and waveform verification after TVS connection for you.

一、Verification of the basic waveform of the lightning strike surge generator

Before the test, the voltage and current waveforms of the surge generator need to be calibrated. This usually involves the calibration of the host and the coupling decoupling network (CDN). 

Before the test, it is necessary to calibrate the voltage/current waveforms of the surge generator (including CDN). The items that must be calibrated include: 

Open-circuit voltage: Peak value, leading time, duration 

Short-circuit current: peak value, leading time, duration 

Verification frequency: During regular checks or calibration periods, compare the open-circuit voltage or closed-circuit current waveforms with the standard. 

The verification method for voltage waveform 

Use a voltage differential probe in conjunction with an oscilloscope to compare the measured waveform with the calibrated set value (note that the voltage rating of the probe must match the testing requirements)

2. The verification method for the current waveform

In the combined wave test, the closed-circuit current waveforms (such as the current waveform from L1 to the neutral line) need to be verified through the CDN line. During the verification process, the power supply of the EUT should be disconnected to avoid damaging the measuring equipment. Commonly used equipment includes oscilloscopes, current monitoring probes (such as HKS-20KA with a calibration capacity of 20kA), and attenuators.

二、Key points for waveform verification after connecting to the TVS device

As the core component for surge protection, the performance of TVS directly affects the waveform characteristics in surge testing. Lebao Electronics suggests focusing on the waveform verification after the TVS is connected in the following scenarios:

1. TVS clamping voltage and waveform matching performance

· Verification purpose: To confirm whether the clamping voltage of TVS under surge impact meets the design requirements, and to prevent damage to the subsequent circuit due to excessively high clamping voltage. 

· Testing Method: 

o Connect the TVS to the test circuit and apply the standard surge waveforms (such as 1.2/50μs voltage wave and 8/20μs current wave); 

Use an oscilloscope to synchronously monitor the open-circuit voltage waveform and the clamp voltage waveform at both ends of the TVS diode, and compare the differences between the two. 

Lebao Advantage: The Lebao TVS components adopt a low dynamic resistance design, with the clamping voltage fluctuation range being ≤ ±5%, which can effectively suppress the peak of surges.

2. The influence of TVS response time on waveforms

· Verification purpose: To evaluate the response speed of TVS within the pre-surge wave period, ensuring its rapid conduction under nanosecond-level pulses. 

· Testing Method: 

o Use an electrical current monitoring probe (such as HKS-20KA) to monitor the surge current waveform, and observe the changes in the current rise time before and after the TVS diode conducts; 

Compare the difference in the current front time before and after the TVS is connected. In an ideal scenario, the response time should be less than 1 nanosecond. 

3. Waveform Coordinated Verification of Multi-level Protection Circuit 

· Application scenario: When the circuit employs a multi-level protection scheme of "GDT + MOV + TVS" or "TVS common-mode protection", it is necessary to verify the waveform coordination of each component. 

· Verification Points: 

o Monitor the clamp voltage timing of each level of components to ensure that the front-stage components conduct before the rear-stage components. 

Test the residual voltage waveform of the entire circuit to ensure that the final output voltage is below the tolerance threshold of the subsequent circuit. 

Leiditech Solution: Lei Mou can offer multi-level protection integration solutions, such as the combination of GDT + MOV + SMBJ series TVS, to optimize the waveform clamping effect.

三、Leiditech Electronics: Professional ESD/TVS Components Facilitating Waveform Verification

Shanghai Lebao Electronic Technology Co., Ltd. has been deeply engaged in the field of electromagnetic compatibility protection, focusing on the research and production of EMC-related components. It possesses the following core capabilities: 

· Full range of ESD/TVS products: Covering working voltages from 1.8V to 600V, supporting SOD-123FL, SMA, SMB, SMC, DO-218AB, DO-15, DO-41 and other packages, suitable for different surge testing requirements; 

· Rigorous factory verification: Each TVS model has passed the 1.2/50μs surge waveform test, providing detailed waveform data such as clamping voltage and response time; 

· Application Support Services: Provide customers with suggestions for TVS component selection during surge testing and technical guidance on waveform verification, and assist in optimizing the design of protective circuits. 

Waveform verification is a crucial step in ensuring the accuracy of surge tests and the effectiveness of TVS protection. As a professional TVS component manufacturer, Lebao Electronics always focuses on technology and is committed to providing customers with highly reliable protection solutions. If you want to know more about the application details of TVS in surge tests, please feel free to contact us for communication and exchange! 

Leiditech is committed to becoming a leading brand in electromagnetic compatibility solutions and component supply, offering products such as ESD, TVS, TSS, GDT, MOV, MOSFET, Zener, inductors, etc. Leiditech has an experienced R&D team that can provide personalized customization services based on customer needs, offering the best solutions to customers.