TVS Diodes for Almost All Kind of Applications - High Performance Protection for Green and Sustainable Technologies

PublishTime： 2021-05-26 Article Source：Diotec

To design sustainable or "green" technologies means also to ensure longest possible lifetimes of electronic devices, once they are produced. An important item is here the protection against transient voltage peaks, as they occur on the power grid in case of lightning strikes. Transient Voltage Suppressors (TVS) prevent high voltage surges from damaging sensitive electronic circuits. DIOTEC offers TVS Diodes for almost all kind of applications, and from low up to very high voltage levels. Check out our latest Application Note to find the optimal TVS solution for your project.

Green and sustainable technologies require high performance and low power electronics that operate at low voltages. Interfacing sensitive components like sensors, microcontrollers, data converters etc. to the real world, or connecting them to other circuits like inductive loads can expose them to voltage surges higher than their specified maximum limits. In order to avoid permanent damage, caused by voltage transients, designers must take protection measures that isolate the active circuit from such events while not affecting operation during normal conditions. Diotec’s portfolio of Transient Voltage Suppressors (TVS) offers a wide variety of solutions for a broad range of applications.

TVS Diodes are silicon devices designed to protect against voltage surges greater than a desired maximum level. When connected in parallel to the circuit, they create a protective path around it (Fig. 1, Fig. 2). During normal conditions, when the input voltage stays within the desired limits, the TVS diode exhibits a high impedance, thus not affecting the behaviour of the downstream circuitry. As soon as the maximum voltage level is reached, the avalanche effect kicks in and the TVS Diode creates a low impedance path, thus diverting all excessive energy into the ground. Like this, the circuit remains unharmed and normal operation can continue.‘

TVS Diodes are available for a multitude of voltage ranges, both as unidirectional and bidirectional types. Unidirectional TVS Diodes have an asymmetrical behaviour protecting against surges of one polarity (Fig. 1., Fig. 3). For signals of the opposite polarity they work much like a standard rectifier. Some applications require protection against both positive and negative voltage spikes. For these cases, bidirectional TVS diodes are the solution of choice (Fig. 2). They have a symmetrical characteristic, blocking excessive energy of both polarities (Fig. 4).

When selecting a TVS Diode, designers must make sure that it is capable of accommodating the maximum expected voltage spikes. The definitions below shall provide a better understanding of the datasheet parameters.

• P_PPM: The Peak Pulse Power Dissipation is a measure of the diode's ability to dissipate energy and is defined as the peak pulse current I_PPM multiplied by the maximum clamping voltage V_C. Because surges are time-dependent, transient phenomena, P_PPM is specified with a pulse current of 10/1000 µs: 10 µs rise to peak and 1000 µs exponential decay to one-half peak (Fig. 5). For non-repetitive pulses, the peak power must stay below the curve in Fig. 6 at all times.

• V_WM: The Stand-off Voltage is the maximum specified voltage at which the TVS diode operates in high impedance mode without entering in breakdown.

• V_BR: The Breakdown Voltage is the value at which the TVS device will start con ducting. V_BR is specified at a fixed current level and is usually ca. 10% higher than V_WM.

• V_C: The Maximum Clamping Voltage defines the voltage across the TVS diode at maximum current I_PPM. The below formula applies:

P_PPM= I_PPM x V_C

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