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STE Portfolio Covers Filtering and Protection in Power Electronics

Original report

STE edition

Adapted from Chongdiantou

Chongdiantou profiles STE capacitors, varistors and thermistors, with surface mount formats for compact assemblies and distinct roles in filtering, surge protection and inrush limiting.

STE's capacitor, varistor and thermistor portfolio was the subject of a Chongdiantou feature published in July 2024. The report highlighted both conventional leaded components and surface mount formats, with an emphasis on the filtering and protection functions needed in compact power electronics.

The products perform different jobs. Ceramic and film capacitors provide capacitance for specified filtering or circuit functions; varistors limit transient overvoltage; power NTC thermistors help limit inrush current. Combining these families can address several requirements in one power supply, but each component must be selected for the electrical conditions at its own circuit position.

Surface mount products for compact assemblies

The report led with STE surface mount Y capacitors. Their low-profile body offers an alternative to an upright leaded component and supports surface mount assembly. A Y designation identifies a safety-capacitor classification. It does not mean that the component creates an additional isolation layer or independently certifies the surrounding circuit.

For a specific mechanical reference, the SMD-X1Y1 3225 drawing dated March 22, 2025 lists a nominal body of 8.1 × 6.0 × 2.5 mm, with ±0.3 mm tolerances on those dimensions. This later drawing clarifies the earlier report's approximate 2.5 mm height: nominal height must not be treated as maximum height. The terminal geometry and required board clearance also remain part of the layout.

Chongdiantou also described an SMD MOV and SMD NTC thermistors. These formats bring overvoltage protection and inrush-limiting components into surface mount assemblies. Device ratings, packaging and soldering conditions should be checked for the specific product. Surface mount construction alone does not establish a production-cost saving or a measured improvement in reliability.

Leaded protection components remain part of the portfolio

The feature included conventional NTC thermistors with silicone-resin encapsulation. STE's PS-series specification lists disc sizes from 5 to 25 mm. Resistance, steady current and temperature limits depend on the selected device; a maximum stated for one option should not be assigned to the entire family.

NTC resistance decreases as temperature rises. In a power inrush-limiting application, initial resistance helps constrain turn-on current, while self-heating changes resistance during operation. The electrical and thermal conditions during a brief power interruption therefore deserve separate consideration from a cold start.

For varistors, the report emphasized surge absorption. A MOV conducts more strongly as the applied voltage rises through its nonlinear characteristic. It does not need to operate a fuse during every transient. Fuse or thermal-protection coordination must account for sustained faults as well as transient events.

Capacitor families have distinct operating envelopes

The source discussed film and ceramic capacitors as additional parts of STE's offering. Film construction, safety classification and circuit duty must be considered together. Two examples illustrate why a portfolio-wide capacitance range is insufficient:

Capacitor families have distinct operating envelopes
STE familyCapacitance in the cited specificationOperating temperatureTypical selection context
MPX/X2, revision April 8, 20240.001–10 µF−40 to +110 °CAcross-line interference suppression
MPP/CBB21, revision October 16, 20230.01–3.3 µF−40 to +105 °CHigh-frequency, DC, AC and pulse circuits within part-specific limits

Ceramic safety capacitors likewise need the correct class, capacitance, voltage and approval for their intended connection. General statements about ceramic stability or application sectors cannot replace those requirements.

The feature presents the breadth of STE's offering, rather than a universal component recommendation. Engineers can explore the STE product families and provide the intended circuit, waveform, temperature and mechanical constraints when requesting part specifications. STE product families

Technical references

  • STE SMD-X1Y1 3225 specification, revision 2025-03-22, pp. 4–6.
  • STE PS-series NTC specification, revision 2022-08-04, pp. 1–2.
  • STE MPX/X2 specification, revision 2024-04-08, pp. 1–2.
  • STE MPP/CBB21 specification, revision 2023-10-16, pp. 1–2.

Figures and tables from the original report

The following figures retain their original captions, markings and historical context. Transcribed tables present the values shown in the published images; product selection should use the specifications for the selected part.

Illustration from the original report — source figure 1
Figure 1. Illustration from the original report. Image: Chongdiantou. Image source
Illustration from the original report — source figure 2
Figure 2. Illustration from the original report. Image: Chongdiantou. Image source
Illustration from the original report — source figure 3
Figure 3. Illustration from the original report. Image: Chongdiantou. Image source
Illustration from the original report — source figure 4
Figure 4. Illustration from the original report. Image: Chongdiantou. Image source
Illustration from the original report — source figure 5
Figure 5. Illustration from the original report. Image: Chongdiantou. Image source
Illustration from the original report — source figure 6
Figure 6. Illustration from the original report. Image: Chongdiantou. Image source
Illustration from the original report — source figure 7
Figure 7. Illustration from the original report. Image: Chongdiantou. Image source
Illustration from the original report — source figure 8
Figure 8. Illustration from the original report. Image: Chongdiantou. Image source
Illustration from the original report — source figure 9
Figure 9. Illustration from the original report. Image: Chongdiantou. Image source

Related reading cited by the original report

Chinese source titles are retained below. 多家知名品牌的共同选择，一文看懂松田历年拆解案例 小身材，大能量，STE松田电子推出贴片Y电容

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