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Select the right TVS to protect your products from ESD --- Through the measurement by TLP(Transmission Line Pulsing System) 2012/10/05

Because the IC device sizes have been shrunk to nanometer scale, the consumer electronics, like the laptop and mobile devices, have been designed to be much smaller than ever.  Without suitable protection devices, the functions of these electronics could be reset or even damaged under ESD events.  Currently, all consumer electronics are expected to pass the ESD test requirement of IEC 61000-4-2 standard.  TVS (Transient Voltage Suppressor) is generally designed to bypass the ESD energy, so that the electronic systems can be prevented from ESD damages.  Therefore, how to select a right TVS product to improve the ESD level of electronics has already became an important issue.  The working principle of TVS is shown in Figure 1.  In Figure 1, the TVS devices are connected in parallel with the protected circuits on the PCB.  These TVS devices would be triggered immediately when a large ESD current impacts into these circuits.  In that way, each TVS device can provide a superiorly low resistance path for discharging the transient ESD current, so that the energy of the ESD transient current can be bypassed by the TVS devices.  The performance of TVS products is generally evaluated by their turn-on speeds under ESD impacts.  However, not only the turn-on speed, but also the clamping voltage of TVS products should be low enough to avoid the protected circuits from resetting, crashing or even damages when an ESD event appears.  Actually, the low-level clamping voltage has been an important factor for evaluating the performance of TVS products.

So, how to measure the clamping voltage of a TVS product under an ESD event?  The TLP (Transmission Line Pulsing) system is an available tool for TVS clamping voltage measurement.  The TLP system was first proposed by T.J. Maloney of Intel Corporation at 1985.  Its system architecture is shown in Figure 2.  It was developed to characterize the current-voltage curve of a DUT (device under test) under a large ESD current with a very short discharge period.  For a TLP generated pulse, its pulse period is in the scale of 100 nanoseconds, but the current amplitude can be reached to several amperes.  Hence, the current-voltage characteristics of the TLP generated pulse can be simply used to simulate the current-voltage response for a DUT under an ESD event.  Therefore, the measured current-voltage characteristics of a TVS protection device under a TLP generated pulse can be used to predict the turn-on voltage and the clamping voltage of the TVS device under ESD events.  With a lower turn-on voltage, the TVS device can be turned on faster to protect the DUT.  On the other hand, being with a low clamping voltage for a TVS device indicates that the performance of the TVS device is better.  Figure 3 shows the measured TVS current-voltage characteristics by the TLP system.  The turn-on voltages and clamping voltages of several kinds of TVS devices are compared in this figure.

Amazing Microelectronic Corp. (AMC, http://www.amazingIC.com/) is the ONLY ESD IC provider in Taiwan who can provide all needs of ESD protection devices.  All the provided ESD protection ICs can help our customers’ electronic products to EASILY meet the Level 4 requirement of IEC 61000-4-2 standard.  With careful design considerations, the AMC TVS products not only can sustain high ESD immunity, but also with fast turn-on speeds and the lowest clamping voltages under ESD events when comparing with the ones provided by other competitors.  Consequently, the AMC TVS products are the best choice for ESD protection design of electronic products.
 

Figure 1

Figure 2

   

Figure 3

 

 

 

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