Overvoltages and the resulting high surge currents can damage or even destroy electrical and electronic devices. Reliable overvoltage protection is therefore essential. Using a new ceramic material, TDK has now developed a series of multilayer varistors with high surge capabilities, combining compact dimensions with outstanding performance.

Overvoltages affecting electrical devices can arise from various sources, carry different energy levels, and enter systems through multiple paths.

ESD pulses, for example, which are measured according to IEC 61000-4-2, primarily impact the I/O ports of communication devices. These are tested using a voltage of either 8 kV for contact discharge or 15 kV for air discharge. The associated pulse shapes are characterized by an extremely steep edge with rise times in the nanosecond range. However, the energy level of these pulses is relatively low at just a few millijoules. For protection against ESD events, TDK offers a wide range of multilayer varistors (MLVs) in SMD packages across various voltage ratings. The smallest design has a footprint of just 0.4 mm x 0.2 mm with an extremely low height of only 0.23 mm. These varistors are therefore commonly used in compact mobile applications, such as smartphones, tablets, and wearables.

Another form of overvoltage is primarily injected into power supply lines. It may be caused by nearby lightning strikes or by load shedding. These events can cause surge currents of several kiloamperes that last microseconds. In the worst-case scenario, the energy of these pulses can carry several thousand joules of energy, which is several times greater than the energy levels encountered in ESD events. The ability of components to withstand these high-energy pulses is measured according to IEC 61000-4-5, using an 8/20 μs pulse shape for the short-circuit current and a 1.2/50 μs pulse shape for the open-circuit voltage (see Figures 1 and 2).

Pulse shapes according to IEC 61000-4-5

Figure 1:

Measurement of the short circuit current (8/20 μs)

Figure 2:

Measurement of the open-circuit voltage 1.2/50 μs

To ensure effective protection against such events, protection devices must be designed to handle the expected leakage currents and the corresponding energy levels. This is why conventional varistors tend to be relatively large.

New ceramic material enables more compact designs

To improve the performance and compactness of multilayer varistors, TDK has developed a new ceramic material for its new high-surge series of multilayer varistors. Thanks to a higher doping of the ZnO varistors with a special metal oxide, the new ceramic material boasts improved properties and a finer granular structure. This creates significantly more grain boundaries per unit of volume. Consequently, the current density can be increased by more than threefold within the same active volume of the component. At the same time, the relative permittivity increases severalfold, enabling a considerably higher electrical field strength (EV) – also within the same volume (Figure 3).

Figure 3:

Comparison of the conventional and new ceramic material TDK’s new multilayer varistors have a higher field strength thanks to their finer granular structure, which is achieved through a special metal oxide doping of the ZnO ceramic material. This results in two benefits: First, a higher number of internal electrodes can be integrated into the same component volume, thereby improving the high-surge performance. Second, the same performance can be achieved in a smaller component, permitting further miniaturization of the varistors.

Thanks to their improved electrical properties, varistors can now be designed with a higher voltage class by increasing the number of internal electrodes. This significantly raises the surge current capability of the component and allows for shrinking the component size for a given performance level. For example, standard varistors with a surge current capability of 1200 A (8/20 μs) are manufactured in an EIA 2220 case size. With the new ceramic, TDK has achieved the same performance in a 1210 form factor. This corresponds to a volume reduction of more than three times. The new varistors are therefore generally used in Internet of Things (IoT) and Industry 4.0 applications, where miniaturization plays a crucial role.

Lower clamping voltage and higher performance

Thanks to the higher permissible field strength of the new TDK ceramic material and the increased number of internal electrodes, the clamping voltage of the components has also been reduced. The clamping voltage is the value at which the varistor becomes conductive. At a given current level, an increase in clamping voltage leads to higher electrical power (P = V∙I), and ultimately, greater dissipation (E = P∙t) within the varistor. Conversely, smaller clamping voltages allow higher currents to achieve the same energy absorption capability.

For example, the TDK type CT2220K50E2G multilayer varistor from the existing surge protection series has a specified clamping voltage of 135 V at 10 A. In contrast, the new TDK CT2220S50E3G high-surge low-clamp type with the improved material achieves a surge current capability of 400 A at the same clamping voltage (Figure 4). Consequently, the new type provides a significantly higher protection level.

Figure 4:

Higher surge current capability at the same clamping voltage. The new TDK high-surge/low-clamp varistor allows for a surge current of 400 A at a clamping voltage of 135 V.

Fewer components, better protection

To achieve the highest possible surge current capability with SMD multilayer varistors, multiple components are often connected in parallel. However, since varistors have voltage tolerances of up to ±20 percent, it is necessary to use precisely matched components for such applications. This represents a considerable cost factor. Another drawback is that, even with tight tolerances, the electrical characteristics of the individual components vary slightly. Consequently, during an overvoltage event, the current is distributed unevenly among the components, which can cause the most heavily loaded varistor to fail.

Thanks to the new TDK ceramic material, high surge current capability can now be achieved in a single varistor. This enhances reliability, reduces component count, and saves both PCB space and assembly costs.

Key data

• Ultra-compact micro POL module FS3303 delivers 3 A in a 2.5 × 2.5 mm footprint with only 1.2 mm height, enabling high-density power for optical modules and AI edge systems
• High efficiency up to 95% with operation up to +90 °C (and +125 °C with derating), supporting low-voltage rails from 0.4 V to 3.3 V for ASICs, SoCs, DSPs, and AI chipsets
• Integrates controller, driver, MOSFETs, and inductor in TDK’s advanced 3D chip-embedded package, minimizing external components and maximizing board space savings

TDK Corporation (TSE: 6762) today announced the FS3303, the first member of a major expansion of its micro POL family of ultra‑compact, non‑isolated DC‑DC power modules for optical modules in AI edge systems and other space‑constrained designs. Despite its small footprint of just 2.5 x 2.5 mm and a height of only 1.2 mm, the FS3303 can deliver 3 A at ambient temperatures of up to +90 °C (up to +125 °C with derating) and boasts a peak efficiency of around 95%. The FS3303-0400-AL is in full production and is sampling at major distributors.

The FS3303 and the upcoming high‑performance point‑of‑load (POL) converter lineup spans 3 A to 80 A output across 0.3 V to 3.3 V rails. They enable next‑generation optical networking and AI accelerator platforms to push performance without sacrificing board space. An example is compact optical modules, which are scaling from 10 Gbit/s to 1.6 Tbit/s. The new portfolio delivers height profiles between 1.2 mm and 1.7 mm.

Engineered for low‑voltage rails, the FS3303 supports input voltages from 2.7 V to 6 V and output voltages from 0.4 V to 3.3 V. This makes it a versatile solution for ASICs, SoCs, DSPs, and emerging AI chipsets requiring tight regulation and high transient performance.

The FS3303 leverages TDK’s proprietary 3D chip‑embedded packaging technology, integrating the controller, driver, MOSFETs, and power inductor. This architecture minimizes external components and delivers a complete DC‑DC solution with exceptional area and height savings—ideal for next‑generation optical transceivers and edge AI modules.

TDK Corporation (TSE: 6762) presents the B82722V6*B040 series of new compact high-voltage, current-compensated ring-core double chokes. Designed primarily for rated DC voltages of up to 1250 V (630 V AC), these compact common-mode chokes (23 x 15.5 x 24 mm) effectively suppress EMI in next-generation applications. These include power converters, industrial motor drives, and switch-mode power supplies that often deploy SiC and GaN power semiconductors and feature elevated DC bus voltages, where insulation coordination and PCB space are critical.

The series covers nominal inductance values ranging from 3.3 mH to 22 mH, with rated currents between 0.85 A and 3.0 A at a rated ambient temperature of +70 °C. Multilayer solid insulation construction and testing with voltages of 3,750 V (line-to-line) ensure robust electrical isolation. Thanks to the special automated winding technique, these chokes feature high resonance frequency characteristics and a typical stray inductance of around 0.6%, helping to suppress symmetrical interference.

The epoxy coating of the ferrite core and the plastic header comply with UL 94 V-0. The design fulfills the latest IEC 60938-2 and IEC/UL 60939-3 safety requirements for EMI chokes and filters. Suitable for wave soldering and offered in a compact vertical design, the B82722V6*B040 series enables engineers to realize 1250 V DC high-voltage architectures without increasing the PCB footprint.

TDK Corporation (TSE:6762) has introduced the G series of surge protection components, comprising the G14 (ordering code: B72214G) and the G20 (B72220G). Integrating a metal oxide varistor (MOV) and a gas discharge tube (GDT) into a single hybrid design and connecting them in series leverages the strengths of both elements. This configuration reduces leakage current to virtually zero, extends the lifetime of the whole component, and provides superior surge protection compared to using either element separately in parallel. These new components are commonly used in power supplies, chargers, appliances, surge protection devices, and communication systems that demand both efficiency and reliability.

Innovation through series hybrid design:

• Zero standby leakage current: With the GDT isolating the MOV during normal operation, leakage currents are virtually eliminated, maximizing efficiency.

• Extended MOV lifetime: The MOV is only engaging when the GDT has fired, drastically reducing stress and aging.

• Reliable surge handling: When fired, the GDT quickly becomes low resistive and acts as the "first line of defense." Meanwhile, the MOV clamps residual voltages, absorbs remaining energy, and eliminates follow-current to prevent the GDT from reigniting.

• Compact integration: A single hybrid device simplifies design and reduces board space compared to discrete solutions.

The G series is available in two leaded versions: G14 and G20, which refer to MOV disk diameters of 14 mm and 20 mm, respectively. G14 models support AC operating voltages from 50 V to 680 V, while G20 versions extend this range to 750 V. The maximum surge current capability for a single pulse (8/20 µs) is 6,000 A (G14) and 10,000 A (G20), absorbing up to 200 J (G14) or 490 J (G20) of energy. Their operating temperature range is specified as -40 °C to +105 °C.

TDK Corporation (TSE:6762) has expanded its ultra-low clamping voltage TVS diode lineup with three new models in the SD0201 series, tailored for high-speed consumer electronics interfaces. These TVS diodes offer compact protection for USB Type-C, HDMI, DisplayPort, and Thunderbolt connections in smartphones, laptops, tablets, wearables, and networking devices.

Each component comes in a 0201 chip-scale package (CSP), measuring just 0.58 x 0.28 x 0.15 mm (L x W x H) for space-constrained designs. Having working voltages of ±1 V, ±2 V, and ±3.6 V, the new TVS diodes safeguard sensitive circuits from electrostatic discharge (ESD) and transient surges. This means they meet IEC 61000-4-2 standards with ESD discharge robustness up to ±15 kV and support surge current handling up to 7 A, depending on the variant. Their symmetrical design enables bidirectional protection and thus flexible PCB routing, while very low leakage currents and dynamic resistance as low as 0.16 Ω enhance application-level efficiency.

The individual components differ in their DC working voltage and parasitic capacitance: the SD0201SL-S1-ULC101 (ordering code B74121U1036M060) has a working voltage of ±3.6 V and a parasitic capacitance of 0.65 pF, the SD0201-S2-ULC105 (B74121U1020M060) of ±2 V and 0.7 pF, and the SD0201SL-S1-ULC104 (B74121U2010M060) of ±1 V and 0.15 pF. A LTspice model library for SEED simulations for TVS diodes is available for download.

TDK’s new ultra-low clamping voltage TVS diodes are engineered to meet the challenges in today and tomorrow’s consumer electronics, ensuring reliable performance and safeguarding sensitive electronic devices from damaging transients.

• New 100-V product for commercial applications with 1 μF capacitance in 1608 case size (achieving large capacitance)
• Contributes to the reduction of component count and the miniaturization of sets

TDK Corporation (TSE: 6762) has expanded its C series for commercial multilayer ceramic capacitors (MLCCs) to 1 µF at 100 V in the 1608 size (1.6 x 0.8 x 0.8 mm – L x W x H), with X7R characteristics. This is the industry’s highest capacitance* for a 100-V-rated product in this size and this temperature characteristic. Mass production of the product series began in June 2025.

In recent years, 48-V systems have become increasingly common for AI servers, energy storage systems, and a wide range of industrial equipment to improve system efficiency and reduce power loss. This has led to a growing demand for 100 V-rated MLCCs used as capacitors on power lines.

This new 100-V product of the C series achieves ten times the capacity of conventional products of the same size, thanks to optimized material selection and product design. Therefore, it makes it possible to reduce the number of MLCCs used and the mounting area, contributing to the reduction of component counts and miniaturization of sets. TDK will further expand its lineup to meet the needs of customers.

*Source: TDK, as of June 2025

• The smallest size in the industry* in the 0201 size
• Achieves high-frequency characteristics through proprietary patterning and sintering technologies
• Lineup of inductances with fine increments, taking advantage of the features of the multilayer method
• Wide temperature range of -55 °C to +125 °C

TDK Corporation (TSE: 6762) announces the expansion of the MUQ0201022HA series* of high-frequency inductors. The 0201 size (0.25 x 0.125 x 0.2 mm; L x W x T) are the smallest inductors of their kind in the industry with the same electrical characteristics as the existing MHQ0402PSA series, which is one size larger at 0402 (0.4 x 0.2 mm; L x W). The lineup covers an inductance from 0.6 nH to 3.6 nH. Mass production of these new components began in May 2025.

As mobile devices such as smartphones and wearable devices become increasingly sophisticated and compact, there is a growing need for small-sized, high-performance components. By applying its proprietary patterning and sintering technologies, TDK has achieved high-frequency characteristics equivalent to or better than existing products while reducing the component mounting area by around half. TDK will further expand its line to meet the needs of customers.

*Source: TDK, as of May 2025