Chip varistors and TVS diodes are commonly used as over-voltage protection components. Their structural design and manufacturing methods are completely different, but they offer similar characteristics with regard to protection from static electricity. They generally can therefore be used interchangeably in a circuit, but there are cases where chip varistors are considered to be not suitable. For historical reasons, many of the specification items given in catalogs and data sheets are different, which makes it difficult to compare characteristics based solely on these data, unlike in the case of capacitors and other general components. The aim of this article is to clarify the difference between varistors and diodes and to introduce data that can be used to compare the two.
DK Corporation (TSE:6762) presents the EPCOS Compact S14 AdvanceD-MP series of metal oxide disk varistors that feature smaller dimensions with the same excellent performance as comparable S14 AdvanceD-MP types. The disk diameters of the new B72214P2* varistors range from 13 mm to 14 mm, a reduction of approximately 3 mm.
Industry 4.0 is being shaped by the continuing rise in the degree of automation, by the digitalization that includes the Industrial Internet of Things (IIoT) and by high levels of energy efficiency. In this respect, TDK presents a wide range of innovative EPCOS and TDK key components.
High-power loads are a major stress factor when fuses and components are switched on, as they cause very high currents to flow. To avoid this, TDK offers ceramic EPCOS inrush current limiters, based on NTC and PTC thermistors – a strong duo when used in combination.
TDK Corporation (TSE:6762) has extended its EPCOS ThermoFuse™ family of fuse protected varistors with the new compact NT14 and NT20 series. The new ThermoFuse components feature a footprint that fits into existing circuit board layouts.
TDK has an extensive lineup of inrush current limiting NTC thermistors available. This article describes various example applications of these products, used for ICL (inrush current limiting) purposes to easily and effectively suppress inrush current. When power is first applied to electronic devices such as switching power supplies and inverters, an instantaneous current with an abnormally high peak will flow through them. This is known as “inrush current” and if not addressed, can lead to problems such as semiconductor element failure or reduced service life of smoothing capacitors. However, our inrush current limiting NTC thermistors can provide protection against this phenomenon to prevent such undesirable effects.
One of the properties of PTC thermistors is that when an excessively large current flows, they generate heat by themselves and become highly resistive. With this property, they are used as overcurrent protection devices. This article describes applications for inrush current limiting, overcurrent protection and telecom application.
PTC thermistors have the property that their resistance rises significantly when a certain temperature is exceeded. This property makes them suitable for use as temperature protection devices that detect defined high temperatures to protect circuits from overheating. TDK offers various types of PTC limit temperature sensors and motor protection sensors that incorporate PTC thermistors and serve as temperature protection devices. This article describes typical applications of such sensors.
Varistors can be used as suppressors to protect devices and circuits from transient abnormal voltages including an ESD (electrostatic discharge) and a lightning surge. For protection from a relatively large surge current (100A to 25kA), leaded disk varistors and SMD disk varistors are suitable. For protection from a larger surge current (approximately 25kA or more), block varistors, and strap varistors are suitable. This article describes surge protection device applications for LED lighting system, inductive loads such as motors, motor with an electromagnetic brake, SSR (solid-state relay), load dump and field decay, joint boxes and power conditioners of solar power generation systems, important devices using a lightning transformer, and high-energy surge in industrial devices.
SMD or chip varistors are voltage-dependent resistors based on ceramic multilayer technology. They are widely used to protect electronic circuits in consumer devices and telecom, industrial and automotive applications against transient overvoltages, such as electrostatic discharges (ESD) and surge transients.
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