Introduction

Electrostatic discharge (ESD) is a major cause of malfunction and failure of electronic devices.
ESD tests to evaluate this are carried out in a variety of fields based on international standards such as IEC 61000-4-2.
In ESD testing based on the IEC 61000-4-2 standard, we focus on the fact that the discharge current waveform consists of two peaks: the first peak and the second peak.

The nature and challenges of ESD testing

An ESD pulse consists of two peaks: a first peak and a second peak.

 First peak:A high-frequency, momentary current originating fromexternalstraycapacitance

The stray capacitance between the discharge gun of the ESD tester and the large metal plate of the Faraday cage (Ed2.0 1.2m x 1.2m) used for calibration

This generates a momentary (<0.8ns) high current that does not correlate to the IEC61000-4-2 150pF/330Ω setting of the ESD gun.

Second peak:Discharge of150pF/330Ωsettingsimulating a human body with anESD gun

High voltage V is charged to a 150pF capacitor that simulates the human body (see diagram on the right), and then discharged through a 330Ω resistor.

If the size of the metal plate of the product's housing is the same as that of a Faraday gauge, a large first peak will occur, similarto that during calibration. However, since the first peak is generated by the stray capacitance between the ESDgun andthe metal plateof the housing, the first peak will be significantly reducedinsmall,portable devices and other devices that do not have metal parts intheir housings.

TVS Effects Observed in Actual ESD Waveforms

The discharge waveform observed in ESD testing can be attenuated to about one-tenth of its original size by incorporatinga TVS(Transient Voltage Suppressor). Semtech's TVS in particular instantly turns on the high-energy components of the high-frequency first peak andthe second peak, which lasts for about100n, to GND with low impedance, preventing excessive current from flowing into the protectedIC.

Without a TVS, the energy from both the first and second peaks reaches the IC directly, increasing the risk of damage.

By incorporating a Semtech TVS, the energy can be reduced to a level that can be adequately absorbed bythe ESD clamp circuitry insidethe IC.

First and second peak IC destruction modes and countermeasures

1. First Peak

① Pinhole damage in the insulating layer

When destruction occurs due to the first peak of ESD, the extremely high voltage for a short period of time causes destruction that creates a small pinhole-like hole.

2. Second Peak

② Burn damage to the surface

When destruction is caused by the second peak, it is caused by a long surge of about 100 ns, which results in destruction that burns the surface wiring.

Countermeasures for each destruction mode

ESD Breakdown Mode ① – Pinhole Breakdown of the Insulation Layer/To Suppress the First Peak

-Select leadless DFN package products with low pin inductance

-Select a product with a small package and no internal bonding wires

- Place the TVS close to the ESD application point

-If there is a resistor or inductor in the circuit, place it after the TVS.

  

ESD Destruction Mode 2 – Surface Burning Destruction/To Suppress the Second Peak of Applied Energy

-Rdyn Select a TVS with a small dynamic resistance (dynamic turn-on resistance)

Why choose Semtech TVS?

1. Strongly clamps both peaks

Semtech's TVS protects ICs from system-level ESD by turning on and bypassing not only the high-frequency instantaneous high current of the first peak but also the high-energy component of the second peak with low impedance to GND.

This reduces the applied energy to a range that the IC's internal ESD clamp circuit can handle, significantly reducing the risk of IC damage.

 
2. High-speed response and wide bandwidth
Easily meets the rise time of less than 1 ns required by IEC 61000-4-2
High frequency components up to several GHz are also clamped reliably.

3. Extensive lineup and proven track record
It has been adopted in many fields including automotive, industrial, consumer, and communications.
We have a lineup of products that are ideal for the latest compact, high-performance ICs

Summary: Semtech TVS is the answer to ESD protection

Strongly suppresses both the first and second peaks
Supports high speed and high frequency, ensuring peace of mind with the latest standards
With a rich track record and lineup, it is ideal for any application

If you are having trouble with static electricity, first consider Semtech's TVS.

Inquiry / Quotation

If you have any questions about this product or would like a quote, please contact us using the form below.