FAQ

The main difference between these two products lies in the core material. Although their static parameters are identical in the datasheets, their performance varies across different frequency ranges.

AF13A offers better efficiency at higher frequencies above 1 MHz, while MS13A is better suited for general-frequency applications. Customers can select the appropriate model based on their specific operating conditions and application requirements.

If you have any further questions about our products, please contact your ITG sales representative or email us at sales@ITG-Electronics.com.

Both C201371A and C201371B are common mode chokes designed with nanocrystalline core materials.

C201371B is an upgraded version of C201371A. The rated voltage has been increased from 250 VAC to 300 VAC, while the dielectric strength has been improved from 1500 Vrms to 2100 Vrms.

The operating temperature range has also been extended from -40°C to +125°C for C201371A to -55°C to +125°C for C201371B.

The main differences among the DCM, DCN, C20200, and C201371 series lie in their core materials, mounting structures, frequency characteristics, and application requirements.

The DCM series consists of common mode chokes using ferrite core materials. It offers a wide range of models and broad application coverage.
The DCN series uses nanocrystalline core materials, providing a wider operating frequency range and particularly strong performance at lower frequencies. It also offers higher inductance values, up to 190 mH.
The C20200 series consists of vertically mounted common mode chokes using Mn-Zn ferrite core materials.
The C201371 series consists of vertically mounted common mode chokes using nanocrystalline core materials.

In summary, the most suitable series should be selected based on the specific application requirements to achieve the best balance of performance and cost-effectiveness.

Selection Guide: Match the required inductance and choose the lowest DCR; use a low-loss ferrite core with a distributed air-gap or an iron-silicon-aluminum powder core.

10–20 kHz is considered the lower frequency limit for resonant inductors (LLC typically operates at 100–500 kHz). The selection criteria differ from those for high-frequency applications.

Total loss = Core loss + Copper loss. At 10–20 kHz:
• Core loss: Follows an exponential relationship with frequency (F). At 20 kHz, core loss is an order of magnitude lower than at 200 kHz, so it is not the dominant factor.

• Copper loss: The DCR portion (Irms²·DCR) dominates at DC/low frequencies. For the ACR portion (skin + proximity effects), the skin depth δ in copper at 20 kHz is ≈ 0.46 mm. Our RL series products fully meet requirements by utilizing Litz wire.

For the RL series:

• A: Initial design version, featuring a single air-gap structure.
• B: Same inductance as A, but with different ACR characteristics; may utilize a distributed air-gap design.
• C: Same inductance as A and B, but with different ACR characteristics.

300Vac,400Vdc follow IEC 61558-2-16

1. Rated Voltage
The maximum voltage level guaranteed by the manufacturer for long-term reliable operation, determined by considering insulation, temperature rise, and safety standards (UL/IEC).

2. Peak Voltage
The maximum instantaneous voltage value within a given time period. It is determined by the rated voltage, waveform shape, and possible transient superimposed components.

3. Dielectric Strength
Applying a specified high voltage (power frequency AC) to the product's insulation for a set duration (1s or 60s) to verify no breakdown or flashover occurs.
Reference standards: IEC 61558-1 and IEC 61558-2-16.

Resonant inductors carry a purely AC current, unlike output filter inductors which handle significant DC bias. Their primary loss concerns are ACR and core loss, making DCR a secondary factor rather than a main optimization target.

Resonant inductors require small, precisely controlled inductance values, necessitating a large air-gap. This demands more turns and/or thinner wire, resulting in higher DCR.

However, if the DCR becomes high enough to significantly impact efficiency, optimization is still necessary.

Works in conjunction with capacitors to achieve soft-switching, eliminating switching losses. Increases power density.

For power inductors such as the SDRS104 or SDRH127, their primary drawback is not the presence of shielding—in fact, shielding is generally beneficial. Rather, the trade-off lies in the fact that these older, shielded drum-core designs underperform compared to molded inductors.

To achieve the targets of 10 µH, 3 A, and low DCR, the following differences exist:
1. Power Density Gap: SDRS104 or SDRH127 typically require a larger package size than molded inductors. In other words, molded inductors can deliver similar current-handling capability in a significantly smaller volume.
2. Higher Saturation Characteristics—this is one of the more significant engineering differences. Ferrite drum-core inductors like the SDRS104 or SDRH127 typically exhibit a relatively sharp drop in inductance once the saturation current (Isat) is reached, known as a hard saturation characteristic. Molded inductors, by contrast, usually display a more gradual saturation behavior (soft saturation), making converter performance more predictable under overload or transient conditions.
3. Shielding Performance: Although power inductors like the SDRS104 or SDRH127 feature a shielded structure, their magnetic isolation is generally inferior to that of molded inductors, resulting in greater magnetic leakage.
4. Mechanical Durability: Power inductors such as the SDRS104 or SDRH127 are assembled structures, making them less robust than the monolithic, bulk construction of molded inductors—one reason why automotive designs increasingly favor molded inductors.
5. Audible Noise: Power inductors like the SDRS104 or SDRH127 may sometimes produce more noticeable coil vibration (coil whine), particularly under conditions such as: light-load PWM operation, burst-mode regulation, high-ripple-current scenarios. Molded inductors typically suppress vibration more effectively.

I would actually say the disadvantages of SDRS104/SDRH127 are probably acceptable.

If your priorities are: low BOM cost; 2~3 A current rating; standard buck converter topology; consumer electronics applications; operation at relatively higher frequencies — then SDRS104 or SDRH127 parts are often a very reasonable choice.

You would only find sufficient justification to switch to a series like SLNR under the following circumstances: board space is limited (the required size for performance is typically under 10 × 10 mm); cost constraints are extremely tight; lower efficiency is acceptable.

SDRH series is designed for applications demanding high current and high inductance in a relatively large footprint. It uses a ferrite core for lower core loss and is available in variants like the SDRH127B, which is AEC-Q200 qualified for automotive use.

SLNR is the compact, low-profile series for space-constrained designs.

SDRS is the low-profile series for high-density boards.

For your specific needs, if you require high current (>10A) or high inductance (>100µH), the SDRH series is the best fit. If space is critical and you need a compact solution, the SLNR series is more appropriate. For low-profile designs with moderate current requirements, the SDRS series is a good choice.

For 10 µH, 2–3 A applications where cost is the primary concern, it is advisable to avoid ITG’s larger molded inductor series. These products are designed for higher currents and lower DCR, meaning you would ultimately be paying for unnecessary performance.

For designs in the 2–3 A range, although ultra-low DCR cannot be achieved, the efficiency loss is generally acceptable compared to the savings in component cost.

If improving efficiency is required, the additional cost is justified under the following conditions: efficiency is critical; reflow temperature is a key consideration; sustained operation at 3 A load is expected.

If cost reduction is the sole priority, consider the following alternatives:
1. Drum-core inductors: SD105-100MHF or SCH2433T-100MHF. For applications not restricted to SMD packages, the SCH series is particularly ideal, as ITG positions it as a low-cost, high-current inductor family.

For molded SMD designs, try to stay within the 6 × 6 mm to 7 × 7 mm footprint range (e.g., SM2011A-100MHF or SM2511A-100MHF), with a saturation current rating ≥ 3.5 A and DCR around 60–120 mΩ. This typically represents the optimal price point.

In summary, selecting the right part from ITG’s product selection guide or website based on your project’s specific priorities—whether cost, efficiency, or size—will help you achieve significant savings in material costs.

The longer part numbers like SMF252012A or SMF322512A are due to a more descriptive naming convention that encodes physical size directly into the part number. This is different from shorter codes like SM2511A, which use an internal, less intuitive identifier.

Example:

In SMF252012A: The numbers 252012 break down as follows:
25 = Length: 2.5 mm
20 = Width: 2.0 mm
12 = Height: 1.2 mm
This corresponds to a 1008 footprint (2.5 x 2.0 mm).

In short, the longer number provides immediate, valuable information about the component's physical size, while the "A" or "B" at the end identifies the specific series variant with its own set of electrical characteristics.

Your choice depends on your application's priorities:

Choose SM5018Q or SM5026Q if you need automotive-grade (AEC-Q200) reliability.

Choose SM5026A if you need lower core loss and DCR for high-frequency server and networking applications.

Choose SMHC5020 or SMHC5026 if you need the highest possible current (up to 80 A) and can accommodate a taller component.

Choose SM5018A for a versatile, wide-range general-purpose inductor.

Choose SM5018 for a cost-effective, high-current solution with a very narrow inductance range.

SMF2511A (New!) – Lowest DCR and High Power Density: lowest DCR; enables smaller, lighter design; highest Irms current rating; larger terminal area improves thermal and mechanical performance; bottom exit SMT terminals minimize PCB area; lowest power losses over wide frequency range (up to 5 MHz); soft saturation characteristic to withstand high current spikes.

SM2511A (New!) – Lower DCR and Widest Inductance Range: lower DCR; widest inductance range; higher Irms current rating; anti-rust itself; alloy iron powder provides soft saturation; low power losses over wide frequency range (up to 5 MHz).

SMX2511A (New!) – Lower DCR and Widest Inductance Range: lower DCR; widest inductance range; higher Irms current rating and higher saturation current characteristics; coating for rust resistance; composite iron powder provides soft saturation; lower power losses over wide frequency range (up to 5 MHz).

SM2511 – Higher saturation current: higher saturation current characteristics; coating for rust resistance; iron powder provides soft saturation; low power losses over wide frequency range (up to 5 MHz).

SM2515A: The High-Current Powerhouse. This series is physically taller (4.0mm) than the others. This extra height allows it to handle very high currents (up to 65A) with extremely low DCR (as low as 0.66 mΩ). It is designed for applications that need to deliver a lot of power in a compact space.

SMF2511Q: The Automotive-Grade Choice. The "Q" in the name stands for AEC-Q200 compliant. This is the only series in this list that is certified for automotive applications, meaning it has passed rigorous reliability and stress tests.

ITG's molded inductor part numbers is a series identifier used to differentiate between variations (often in size or performance) within the same product family. For the exact meaning in a specific case, you should always refer to the relevant series datasheet on the ITG Electronics website.

SM Series: Lower DCR and lower core loss. This is ITG's general-purpose line of molded inductors. It serves as the foundation for many applications where a specific, targeted optimization isn't the primary requirement. The SM, SMHC and SMF, SMX series share a common appearance criteria document.

SMHC Series: High current and low DC resistance (DCR) and low core loss, making them ideal for high-performance computing, servers, and voltage regulator modules (VRMs).

SMF Series: SMF indicates a focus on high-frequency operation, typically up to 5MHz. They are available in very compact footprints, such as the 2.5 x 2.0 mm size, making them suitable for space-constrained, high-frequency applications like those in smartphones and portable devices, DDR, VRM and so on.

SMX Series: SMX denotes a series engineered for better performance, combining very high current with ultra-low DCR. For instance, the SMX40187A series can handle up to 120A with a DCR as low as 0.24 mΩ. This positions the SMX series for the most demanding power conversion tasks.

If you are interested in ITG’s molded inductors, their product line covers a full range—from commercial-grade inductors to automotive-grade, high-current power inductors. These designs are optimized for both PCB space utilization and cost efficiency.

Key features include: low DC resistance (DCR); high saturation current; minimal footprint.

In many buck converter applications (e.g., 12V → 1V or 5V → 1.xV), moving to a larger package size often delivers greater efficiency gains than expected. This is because copper and core losses decrease significantly, while the cost increase remains modest.

Of course, ITG offers flexible pricing for its molded inductors, with purchase volume being a key factor. Sample quantities command higher prices, whereas volume purchases can lead to substantial discounts through negotiations with distributors or directly with the manufacturer.

Thanks to their integrated molded core structure, these inductors exhibit soft saturation characteristics and excellent EMI performance. While their electrical performance may resemble that of automotive-grade parts, choosing an automotive-qualified version entails additional costs covering: AEC-Q200 certification (more rigorous reliability testing); extended temperature validation (wide-temperature design supporting –55°C to +85°C, +125°C, or even +165°C, meeting demanding automotive and industrial environmental requirements); longer traceability periods.

If your products are not intended for automotive or industrial applications, these expenses typically represent unnecessary overhead.

Additionally, ITG pursues a differentiated product strategy: its portfolio is exceptionally broad (with packages ranging from 2.2 × 1.8 mm to 17.45 × 17.15 mm) and offers a high degree of customization. This allows ITG to flexibly address niche application needs—something standardized suppliers often struggle to provide. We recommend treating ITG’s product lineup as a configurable platform, leveraging its extensive offerings to precisely match the performance, cost, and reliability requirements of your specific design.