Talk about the parameters of TVS, Yuansheng Da teach you how to select TVS

Transient voltage suppression diode is a common circuit protection device, and is often mentioned by engineersTVS (Transient Voltage Suppression).TVSIs a diode form of high efficiency protective device with a singlePNKnot or morePNAn integrated device. In the selection of the main reference to the following indicators

1, Maximum operating voltageVWM

When working normally,TVSIt's not supposed to work, soVWMIt should be greater than the highest working voltage on the line. So as to ensure thatTVSThe circuit will not be affected under the normal operation of the circuit. But do not choose too high, if too high, clamp voltage will be high, so in the selectionVMMWhen, the working voltage of the protected circuit and the bearing capacity of the post-stage circuit should be considered comprehensively.

2, Breakdown voltageVBR

The breakdown voltage is defined atV-lCharacteristic curve at specified pulse DC currentIROr near avalanche current conditionsTVSThe voltage at both ends. For low pressureTVS, because the leakage current is large, so the test current is selectedIRLarger, asSMAJ5.0A, test currentIRselect10mA. Make the pulse constant current source pairTVSimposeIRThe size of the current when readTVSThe voltage at both ends is the breakdown voltage. The current application time should not exceed400msIn order not to causeTVSBe damaged by heat.VBR MINandVBR MAXisTVSA deviation of the breakdown voltage, in generalTVSfor±5%The deviation of

3, Clamp voltageVcPeak pulse currentIpp

Ipp: Peak pulse current, peak value of the measured pulse current waveform.TVSGeneral selection10/100μs Current waveform.

Vc: Clamp voltage, applying the peak pulse current of the specified waveformIppWhen,TVSThe peak voltage measured at both ends.TVSClamp voltage should be less than the maximum transient safety voltage that can be borne by the rear protection circuit.

IppandVcIs to measureTVSThe parameter of the ability to resist surge pulse current and limit voltage in circuit protection. These two parameters are related to each other. forTVSThe clamp characteristics in the lightning protection circuit can be referred toVcThis parameter, for the same modelTVSIn the same wayIppinferiorVcThe smaller it is, the betterTVSThe better the clamping characteristics.TVSThe impulse current impact resistance can be referred toIppThe same modelTVS,IppThe larger the size, the stronger the impulse current impact resistance.

4, Rated powerPPPM

TVSThe rated transient power of the product shall be greater than the maximum transient surge power that may occur in the circuit:PPPM=Vc*Ipp

5, Leakage currentIR

For some low power circuits, special attention should be paidIR. If the voltage allows, try to choose10VaboveTVS, the leakage current will be smaller. There are also low-power onesTVS.

6, Junction capacitance

TVSThe junction capacitance is generally in the tenspFTo dozensnF. For the same power classTVSThe lower the voltage, the larger the capacitance value. On some communication buses, especially high-speed lines, pay attentionTVSExcessive junction capacitance may affect the bus.

7, Encapsulation form

TVSThe power from the packaging form can also be reflected, packaging volume is smaller, its power is generally smaller, becauseTVSThe chip area is directly determinedTVSThe power level of Suitable package can be selected according to circuit design and test requirementsTVSDevice.

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