TDK Corporation (TSE: 6762) has introduced the MT40 series of ThermoFuse varistors (ordering code B72240M), a new generation of surge protection components (SPC) that combine a compact design with advanced safety features. Thanks to their patented overmolding technology and integrated thermal disconnecting system, these SPCs provide robust protection up to 50 kA while minimizing size (38.0 x 15.2 x 40.9 mm; L x W x H). Consequently, the MT40 series is commonly used in inverters, industrial power supplies, outdoor lighting, telecommunications systems, and surge protection devices (SPDs).

Designed for extreme electrical conditions, the MT40 series has a peak surge current capability of up to 50 kA (8/20 μs pulse) and a short-circuit current rating of up to 200 kA. The series is recognized as a UL 1449 Type 1CA component assembly, designed for use in applications with AC voltages ranging from 150 V to 550 V and DC voltages spanning from 200 V to 750 V. Additional features, such as a galvanically insulated normally open micro-switch for remote monitoring and an optional visual indicator, enhance system integration and operational safety. These MT40 components operate in temperatures ranging from -40 °C to +85 °C.

Supporting sustainable design practices and aligning with TDK’s commitment to environmental responsibility, the MT40 series is encapsulated in a flame-retardant epoxy coating. Its RoHS compliance and lead-free materials underscore its eco-conscious profile while ensuring high reliability under demanding conditions. By combining innovation, safety, and sustainability, MT40 ThermoFuse varistors offer system designers a compact, future-proof solution for next-generation industrial and communication systems.

TDK Corporation (TSE:6762) extends its X2 safety film capacitor portfolio with the new B3292xU/V series, 
now supporting higher voltages and offering compact lead spacings of 15 mm and 22.5 mm, with capacitance values from 47 nF to 1.8 µF. Rated at 350 V (AC) and robust against peak voltage pulses up to 2.5 kV 
(IEC 60384-14), the series is designed for interference suppression in demanding, space-constrained industrial and automotive environments in series with the mains. Typical applications are on-board chargers, EV charging systems, PV inverters, energy meters, and capacitive power supplies.

The entire series is now available with lead spacings from 15 mm to 52.5 mm, covering capacitance values from 47 nF to 20 µF. It passed the THB (temperature, humidity, bias) test at +85 °C, 85% RH, and rated voltage for 1000 h, meeting Grade III, Test Condition B requirements. In addition, the series offers AEC-Q200 compliance, excellent self-healing properties, and a maximum operating temperature of +110 °C, ensuring durability even under severe ambient conditions.

With their compact dimensions and high DC testing voltage (1505 V for 2 s), the B3292xU/V series provides a balanced solution of performance and size for next-generation industrial drives and automotive power electronics, supporting the growing need for efficient and space-optimized EMI suppression solutions.

For the B3292xU/V series, TDK offers a range of design tools and SPICE models.

TDK Corporation (TSE: 6762) introduces the new B43655 and B43656 series of aluminum electrolytic capacitors designed specifically for DC links in on-board chargers (OBCs) of electric vehicles. Both series are optimized for forced cooling operation, supporting the growing trend toward higher voltages and currents in next-generation OBC platforms. Due to their compact design and high ripple current capability, such capacitors are commonly used in applications requiring maximum efficiency and reliability in confined spaces. 

With a high voltage rating of 475 V and 500 V, as well as capacitances ranging from 110 µF to 880 µF, the B43655 series meets the requirements of 800 V battery architectures for modern e-mobility applications. Designed for base cooling and high ripple current density, these components offer a useful life of more than 3,000 hours at +105 °C. They also feature a maximum ripple current of 3.29 A at +105 °C and ESR values down to 100 mΩ to minimize power losses. The B43656 series, rated at 450 V, handles even higher currents of up to 4.42 A at +105 °C for demanding high-power OBC topologies. 

Both series are qualified according to AEC-Q200 Rev. E and are made with RoHS-compliant materials. They are available in compact snap-in designs ranging in diameter from 22 mm to 35 mm and in length from 25 mm to 60 mm, depending on the capacitance and voltage class. The B43655 and B43656 capacitors provide design engineers with robust, future-ready solutions for on-board chargers in electric vehicles, thanks to their enhanced electrical performance and reliability. 

The new B43655 and B43656 series will also be implemented in TDK’s web-based AlCap Useful Life Calculation Tool. 

TDK Corporation (TSE: 6762) announces the B3271xP series of DC link film capacitors, offering high thermal robustness for demanding automotive and industrial power electronics. With a maximum operating temperature of +125 °C and no power derating up to +105 °C, the series ensures stable capacitance and reliable energy buffering even in tightly packed inverter environments. This performance is particularly relevant for xEV traction inverters, onboard chargers, and DC-DC converters, where elevated ambient temperatures and continuous ripple loads are common.

The B3271xP series covers capacitance values from 0.47 µF to 110 µF and rated DC voltages from 600 V to 1200 V, enabling flexible design-in for frequency converters, high-end industrial power supplies, and solar inverters. Its polypropylene (MKP) dielectric provides inherently low losses, high ripple current capability, and excellent self-healing behavior, maintaining efficiency and extending system lifetime under harsh electrical stress.

Engineered with a flame-retardant plastic case and epoxy sealing (UL 94 V-0), the components are available with lead spacings of 27.5 mm, 37.5 mm, and 52.5 mm, and in 2-pin or, on request, 4-pin configurations to support mechanical stability and low-inductance layouts. Typical ESR values down to the single-digit milliohm range and high current capability at 10 kHz contribute to robust DC link filtering and reduced thermal rise.

Compliant with AEC-Q200E and UL 810 (construction), the B3271xP series delivers the reliability expected in automotive platforms while supporting global industrial requirements. Its combination of high-temperature endurance, broad electrical performance, and compact dimensions helps engineers optimize converter designs for efficiency, stability, and long-term durability.

For the B3271xP series, TDK provides various SPICE model libraries and the web-based Capacitor Life And Rating Application (CLARA) tool.

• µPOL module F1525 delivers 25 A each, up to 200 A when stacking multiple units, for a compact and low-height form factor in vertical power delivery designs
• Ultra-fast transient response, ultra-low DC ripple, and low spectral noise
• Integrates MOSFETs, inductors, and control in a thermally enhanced 3D structure with analog and digital interfaces

TDK Corporation (TSE: 6762) expanded its µPOL family of non-isolated DC-DC power modules by adding the FS1525. This just 3.82 mm high point-of-load (PoL) converter delivers up to 25 A and is engineered to meet the demanding requirements of AI servers, edge computing, and data center systems. By stacking or paralleling several FS1525 modules, they can deliver 200 A combined in vertical power delivery designs. This is a novel approach in which the PoL converters are located directly under the FPGA/SoC or ASIC on the backside of the PCB.

Leveraging advanced 3D chip-embedded package technology, the FS1525 integrates all critical components—including controller, driver, MOSFETs, digital core, memory banks, bypass capacitors, and power inductor—into a single component with a footprint of 7.65 x 6.80 mm (L x W). The thermally enhanced architecture with a thermal impedance of 1.4 K/W delivers superior current performance, outperforming conventional solutions at high ambient temperatures while simplifying PCB routing and enabling high-density power architectures.

Supporting input voltages from 4.5 V to 16 V and an adjustable output range from 0.6 V to 1.8 V, the FS1525 is optimized for powering modern low-voltage AI processors, including the core voltage of 3-nm to 6-nm ASICs, and SERDES rails with sub-5mV peak-to-peak ripple. Its low spectral noise performance matches well with DSPs, imaging, and advanced Automated Test Equipment (ATE) applications. Being scalable up to 200 A and designed for vertical power delivery designs, the new µPOL enhances thermal performance and maximizes board space efficiency.

FS1525 has a fast transient response, low ripple, and true differential remote sensing to ensure accurate voltage regulation at the point of load. Digital programmability via I²C and PMBus enables real-time telemetry, adaptive tuning, and fault management for voltage, current, and temperature monitoring, critical for dynamic AI workloads. The module also offers analog Vout settings tailored to leading FPGA/SoCs and ASICs, supporting advanced features such as Altera’s SmartVID for Agilex FPGA series.

The new µPOL module integrates seamlessly with modern computing form factors, including PCIe, VPX, SMARC, and 1U to 3U rack systems, providing high flexibility for system designers. It is already deployed in proven designs for FPGA/SoCs such as Altera Agilex™, AMD Versal™ Edge, and AMD-Xilinx platforms, including Zynq UltraScale+ MPSoC and Versal ACAP, widely used in AI and machine learning applications.

As part of TDK’s comprehensive µPOL portfolio spanning 1 A to 200 A, the FS1525 offers a unified system-level power solution. With plug-and-play simplicity and no external compensation required, it accelerates development cycles, reduces design complexity, and lowers overall system cost. More than a power module, the FS1525 represents a complete power ecosystem designed to drive the future of intelligent computing. Evaluation boards for 25 A and 50 A are in stock at DigiKey and Mouser. Stackable boards for 100 A and 200 A are available upon request.

Versal is a registered trademark of AMD

Agilex is a registered trademark of Altera

Design collateral for ease of design

• FS1525 Starter Design schematics and PCB layout at Ultra Librarian, URL:
   https://www.ultralibrarian.com/partners/tdk
• FS1525 SIMPLIS model and PDN libraries for top FPGAs/SoCs, URL:
   https://www.us.tdk.com/news_center/upol/index.php
• FS1525 Evaluation boards from 25A, 50A, 100A, and 200A

TDK Corporation (TSE:6762) announces the extension of its high-performance MEMS inertial sensors portfolio with Tronics AXO315®T1, a high-temperature MEMS accelerometer with ±14 g input range and a digital interface for measurement while drilling (MWD) applications operating up to +175 °C.

With this launch, TDK is taking the next step in temperature robustness, following the release of the Tronics AXO315T0 in June 2025 — its first digital MEMS accelerometer to be qualified for oil and gas applications at temperatures of up to +150 °C. This confirms the company's position as a leading provider of high-reliability MEMS inertial sensors for precise downhole navigation in extreme environments.

The AXO315T1 is powered by TDK’s unique closed-loop architecture, which has already been proven on several Tronics sensors. This architecture enables a 10x improvement in vibration rectification error compared to traditional open-loop MEMS accelerometers. The device is a cost-effective, digital, and low-SWaP (Size, Weight, and Power) alternative to quartz accelerometers for inclination measurement in directional drilling tools operating in harsh temperature and vibration conditions.

With a lifetime of more than 1000 hours at +175 °C, it paves the way for a new generation of MWD tools to meet the accuracy and productivity requirements of complex and unconventional drilling operations.

AXO315T1 sensors and evaluation boards are available for sampling and customer evaluations.

SiC and GaN semiconductors push converters to higher power densities and temperatures—but conventional polypropylene capacitors can't keep up. TDK's new ModCap UHP solves this with a PP-COC blend dielectric rated 25 K higher than standard film capacitors. The result: up to 40% smaller DC-link designs for renewable energy, EV, and industrial drive applications.

Power electronics engineers face a familiar challenge: new semiconductor technologies deliver smaller, more efficient converters with higher power output. At the same time, every other component in the system must keep pace. Wide-bandgap (WBG) semiconductors such as silicon carbide (SiC) and gallium nitride (GaN) are driving this shift. Their faster switching speeds, lower losses, and higher junction-temperature capability enable more compact converter layouts that can operate at elevated temperatures. Capacitors must evolve to match these demands (Fig. 1).

Figure 1:

New capacitor requirements based on new semiconductor characteristics.

Modern DC-link capacitors need to handle higher electric fields and larger current densities in smaller packages. They require extremely low equivalent series inductance (ESL) for fast transient response and a low, frequency-stable ESR to minimize losses at high switching frequencies. Internal capacitor design matters too; parasitic effects like skin effect, internal resonances, and non-uniform current distribution can increase ESR and reduce efficiency.

Thermal management has become equally critical. Engineers often mount capacitors close to power semiconductors to minimize loop inductance, exposing them to conducted heat from power modules. Combined with softer cooling systems and higher semiconductor junction temperatures, capacitors face increased thermal stress. They must operate reliably at higher temperatures and current densities without sacrificing lifetime.

This article explains how TDK tackled these challenges by developing a new high-temperature dielectric film and integrating it into the ModCap UHP series, a new generation of modular high-power DC-link capacitors.

A New Polymer Engineered for Higher Temperatures

TDK has worked with industry partners for years to develop a dielectric film material capable of handling higher operating temperatures in metallized film capacitors. Building on earlier work with polypropylene–cyclic olefin copolymer (PP-COC) blends, Borealis and TOPAS Advanced Polymers recently introduced Stelora™ EPN (Ethylene-Propylene-Norbornene).

EPN blends two materials:

• Polypropylene (PP): a proven, easy-to-process dielectric
• Cyclic olefin copolymer (COC): a dielectric with superior temperature capability

COC alone cannot be stretched into a film. When blended with PP, however, the result is a material that processes like standard PP while retaining COC's high-temperature strength.

Figure 2:

Curves of electric field derating vs temperature for the BOEPN capacitors and BOPP capacitors. (Source: [4])

Biaxially oriented EPN (BOEPN) films deliver excellent performance in practice. At moderate temperatures, they self-heal as effectively as standard biaxially oriented polypropylene (BOPP), matching its dielectric strength and capacitance density. At elevated temperatures, BOEPN clearly outperforms BOPP. Even during Accelerated Life Tests (ALT), BOEPN films maintain good self-healing capability, lower leakage current, and higher breakdown strength. This combination prevents thermal runaway under DC voltage stress and ensures robust operation at elevated temperatures.

When used in metallized film capacitors, BOEPN delivers significantly better aging behavior and reliability than BOPP (Fig. 2). Tests at +125 °C show that BOPP-based capacitors age faster. They lose capacitance, show higher losses (tan δ), and exhibit decreased insulation resistance. This, in turn, means higher leakage current and increased risk of thermal failure. BOEPN-based capacitors, by contrast, show only a slow increase in tan δ, primarily from mild electrode oxidation.

Multiple endurance tests confirm this advantage. As Figure 2 summarizes, capacitors using BOEPN withstand higher electric fields above +85 °C, enabling higher capacitance density without derating or a shortened lifetime. With optimized capacitor design and BOEPN integration into ModCap technology, the rated electric field can be pushed even further (Fig. 3)—delivering higher power density and thermal stability for next-generation converters.
 

Figure 3:

Change in the electrical properties of BOEPN- and BOPP-based capacitors (1 μF, 10 pieces per group) over time at a LET of +125 ºC: Left: change of capacitance at 1 kHz, Middle: tan δ at 1 kHz; right: insulation resistance after 10 s at 500 V. (Source: [4])

ModCap UHP: Built for Extreme Conditions

TDK's ModCap HF series (B25647) with BOPP dielectric film has set the benchmark for DC-link capacitors used with advanced semiconductors. Building on this proven platform, TDK now offers the ModCap UHP series (B25648) with the new BOEPN dielectric film. This material enables operation at higher temperatures and current densities without derating, while maintaining the same mechanical design. ModCap UHP targets the most demanding applications where power density, cooling constraints, and temperature push ModCap HF to its limits or even beyond. Typical applications include energy storage systems (ESS), central solar inverters, electrolyzers, high-power DC-DC converters, and auxiliary drives using SiC semiconductors.
 

Figure 4:

ModCap UHP drawing and configuration. (Source: [7])

ModCap HF and UHP share the same modular concept, terminal layout, and external dimensions—ensuring mechanical and electromagnetic compatibility (Fig. 4). Both  feature extremely low inductance (ESL ≈ 8 nH) for fast transient handling, low ESR across a wide frequency range, and ISCC-certified bio-circular polypropylene. They offer identical capacitance values, high voltage strength, and a 200,000-hour lifetime at rated voltage and temperature.

ModCap UHP goes further:

• Up to +21% higher current density, enabling up to +45% higher converter power density in the same footprint
• Rated operating temperature increased from +80 °C to +105 °C without voltage or lifetime derating

This makes ModCap UHP the right choice when converters must deliver more power under demanding thermal conditions—whether due to softer cooling systems or heat transfer from nearby semiconductors.
 

Figure 5:

Capacity change over time (left) for ModCap HF and (right) for ModCap UHP. (Source: [2])

Figure 6:

Mean lifetime of ModCap UHP. (Source: [7])

Testing beyond IEC 61071:2017 and IEC 61881-1:2010 confirms that ModCap UHP maintains aging behavior at +105 °C comparable to ModCap HF at +80 °C—demonstrating excellent stability and robustness under elevated-temperature operation (Figs. 5 and 6). 

ModCap UHP is currently available in rated voltages from 1350 V to 1800 V; Table 1 shows the main electrical parameters. Voltage extensions ranging from 900 V to 2000 V are under development.

Real-World Comparison: ModCap HF vs. ModCap UHP

To verify the practical advantages of switching from BOPP (ModCap HF) to BOEPN (ModCap UHP), TDK conducted a detailed case study on a high-current DC-link application. The goal: assess how the +25 K higher rated temperature and +21% higher current density translate into actual design benefits—performance, volume, and lifetime.

The analyzed converter represents a typical high-power application:

• DC-link voltage: 1600 V
• Total capacitance: ≥1850 µF
• RMS current: 570 A
• Ambient temperature: +75 °C
• Temperature at power module terminals: +95 °C
• DC-link lifetime: ≥200,000 h

Two DC-link configurations were evaluated: one using ModCap HF capacitors (BOPP dielectric) and one using ModCap UHP capacitors (BOEPN dielectric).

ModCap HF Solution

According to the ModCap HF datasheet [8], a suitable starting point is the B25647A1647K003 (1600 V / 640 µF / 160 A). Three capacitors in parallel meet the capacitance requirement (≥1850 µF), but deliver only 480 A (3 x 160 A)—below the required 570 A. At least four units in parallel are needed to satisfy both current and capacitance demands.

Since this configuration is current-limited rather than capacitance-limited, a higher-voltage variant—B25647A11477K003 (1800 V / 470 µF / 150 A)—provides a more robust lifetime margin. The resulting DC-link has a total volume of 15.4 dm³.

Finite element method (FEM) simulations assessed thermal behavior and expected lifetime. These include thermal boundary conditions (ambient temperature, cooling, heat transferred from power modules), the complete current amplitude spectrum over frequency, and electromagnetic effects on internal capacitor construction.

Figure 7:

FEM simulation with the same capacitance, voltage, and current requirements. ModCap HF (left), ModCap UHP (right). Source: [2]

FEM results showed a maximum internal capacitor temperature of +96 °C, caused by self-heating and heat conduction from power module terminals (Fig. 7). Since this exceeds ModCap HF's +80 °C rating, lifetime falls below 200,000 hours—violating the design target.

Maintaining lifetime and thermal margins requires five units in parallel, providing:

• DC-link voltage: 1800 V > 1600 V
• Capacitance: 2350 µF > 1850 µF
• RMS current: 750 A > 570 A
• DC-link volume: 19.3 dm³

While technically feasible, this solution significantly increases both size and cost.

ModCap UHP Solution

For the same 1600 V system, the equivalent ModCap UHP capacitor is B25648A1647K003 (1600 V / 640 µF / 190 A) [7]. This type offers identical voltage, capacitance, and outer dimensions to its ModCap HF counterpart—but features 19% higher rated current and a 25 K higher rated temperature (+105 °C vs. +80 °C).

Three capacitors in parallel fulfill all application requirements:

• DC-link voltage: 1600 V = 1600 V
• Capacitance: 1880 µF > 1850 µF
• RMS current: 570 A = 570 A
• DC-link volume: 11.5 dm³

Total DC-link volume drops by 40% compared to the ModCap HF design.

Thermal FEM simulations under identical boundary conditions revealed a maximum internal temperature of +104.8 °C—just below the +105 °C rated limit. The ModCap UHP design achieves full lifetime without derating: 200,000 hours even under elevated thermal stress.

Summary and Key Takeaways

For the high-current-density DC-link studied, only three BOEPN-based capacitors are required instead of five BOPP-based units. This reduction comes from higher current and power density, combined with the increased rated temperature of the ModCap UHP series.

Figure 8:

DC-link solution with the same capacitance, voltage, current, and thermal-lifetime requirements. ModCap HF (left), ModCap UHP (right). Source: [2]

As Table 2 and Figure 8 summarize, the ModCap UHP solution achieves:

• 40% lower DC-link volume, enabled by 19% higher current density and 25 K higher rated temperature
• 25% lower capacitor cost, excluding additional savings from a smaller external busbar

For applications with demanding current, thermal, and lifetime requirements—such as those using advanced power modules—BOEPN film capacitors deliver a more compact and cost-efficient DC-link design than conventional BOPP-based solutions.

In high-power-density designs like the application analyzed here, the critical DC-link parameters are current density, thermal management, and lifetime. ModCap UHP delivers an optimized balance of volume, capacitance density, current capability, lifetime, and cost—providing a robust, space-efficient solution for next-generation power converters based on advanced semiconductor technologies.

References

[1] M. Gómez, "Innovative film capacitor technologies for wide band-gap semiconductors," IEEE PSMA Capacitor Committee Workshop 2020

[2] F. Rodríguez, "High Temperature Capacitors for Medium Voltage Applications with New WBG Semiconductors," ECPE Hybrid Workshop, Medium Voltage Power Electronics, Freiburg, Germany, 2025.

[3] C. Alba, D. Peláez, and L. Cabo, "High-Temperature Metallized Polymer Film Capacitors Based on Blends of Polypropylene and Cyclic Olefin Copolymers," 2020 IEEE 3rd International Conference on Dielectrics (ICD), Valencia, Spain, 2020, pp. 669-672, doi: 10.1109/ICD46958.2020.9342006.

[4] U. Wahner and C. Alba, "Polymers in Film Capacitors - The Next Generation Material is available!," PCIM Europe 2023; International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management, Nuremberg, Germany, 2023, pp. 1-8, doi: 10.30420/566091018.

[5] IEC 61071:2017 Capacitors for power electronics

[6] IEC 61881-1:2010 Railway applications - Rolling stock equipment - Capacitors for power electronics - Part 1: Paper/plastic film capacitors

[7] ModCap UHP Datasheet, 2025, https://www.tdk-electronics.tdk.com/inf/20/50/ds/ModCap_UHP_B25648.pdf

[8] ModCap HF Datasheet, 2025, https://www.tdk-electronics.tdk.com/inf/20/50/ds/B25647_ModCap_HF.pdf