* Product Parameters
Operating frequency: 20kHz ~ 500kHz, suitable for high-frequency switching power supplies. Operating temperature: -40℃ ~ +125℃ (some models can reach +180℃). Storage conditions: -25℃ ~ +85℃, humidity 30% ~ 95% RH. Insulation withstand voltage: Usually requires AC 2000V, insulation resistance ≥200MΩ (tested at DC 500V).
* Product Features ETD29 is a classic magnetic core with balanced performance and friendly process. It belongs to the medium - small power level. However, within its applicable power range, it has become one of the preferred choices when designing high - efficiency and reliable switching power supplies, thanks to its core advantages of circular winding, good heat dissipation, and low leakage inductance. * Typical Application Areas Switching Power Supply (SMPS):Auxiliary power supply for desktop computer power supplies, industrial control power supplies, LED driver power supplies. Communication Equipment:DC - DC power modules for network routers and switches. New Energy:Auxiliary power supplies in photovoltaic inverters, battery chargers. Industrial Electronics:Power conversion and isolation inside industrial control equipment.
* Product Standards UL, RoHS, 3C, CQC * Dimension Specifications 
Model | Structure Type | Dimensions (mm) | Number of Pins | Pin Pitc (mm) | Row Pitch
(mm) | Pin Diameter
(mm) | Remarks | A | B | C | Pin | E | F | ETD29 - 001 | Horizontal | 37.0 | 38.0 | 26.0 | 7+7 | 5.00 | 26.0 | Φ0.8 |
| ETD29 - 002 | Vertical | 37.0 | 26.0 | 43.0 | 6+6 | 5.00 | 20.3 | Φ0.6 |
| ETD29 - 003 | Vertical | 37.0 | 25.0 | 37.0 | 7+7 | 5.00 | 17.5 | Φ0.8 |
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The above are the commonly used bobbin styles of the company.,Other styles are not listed for the time being.Welcome to consult. Our company can customize high - frequency transformers of various specifications according to customer requirements.
The ETD29 transformer is a highly classic and widely used core shape, particularly prominent in modern switching power supplies. Structural Advantages
External Structure: The ETD core consists of two identical "E" cores joined face-to-face, with a circular center post that pairs with a specialized round bobbin.
Circular Center Post: Primary Advantages: Compared to traditional square center posts (such as those in EE or EI cores), the circular structure makes winding copper wire easier—especially for multiple parallel strands or Litz wire—resulting in higher fill factor and more efficient use of winding space. Better Heat Dissipation: The coils are typically closer to a cylindrical shape, offering a larger contact area with air. Additionally, the thermal coupling between the core and windings is improved, facilitating heat transfer from the interior.
Symmetrical Magnetic Path: The face-to-face structure ensures a highly symmetrical magnetic path, leading to relatively low leakage inductance and reduced magnetic interference.
Generous Window Area (Aw): Relative to its power rating, the ETD series provides a large window area, allowing for thicker wires or more turns, which is advantageous for handling high currents.
Performance Characteristics
Power Handling Capability The ETD29 is typically suitable for switching power supply applications ranging from several tens of watts to over a hundred watts. The specific power range depends on:
Operating Frequency: Higher frequencies enhance power handling. Commonly used in the 50 kHz – 200 kHz range.
Topology: Forward, flyback, half-bridge, full-bridge, etc. For example, in flyback topology, it may handle 60 W–80 W; in forward or bridge topologies, it can reach 150 W or higher.
Cooling Conditions: Good forced air cooling or the use of higher-grade core materials (e.g., PC95) can increase power capability.
Electrical Characteristics
High Efficiency Potential: The symmetrical magnetic path and low leakage inductance help reduce switching losses and EMI. Coupled with suitable winding techniques (e.g., sandwich winding), coupling can be optimized to improve efficiency.
Temperature Rise Performance: The circular coil and good thermal coupling with the core generally result in lower temperature rise compared to EE cores under equivalent conditions. The larger product of effective cross-sectional area (Ae) and window area (Aw) implies a better balance between magnetic flux density and current density.
High-Frequency Performance: The ETD series is designed specifically for high-frequency switching power supplies, offering excellent performance above 100 kHz with controllable core losses.
Design Flexibility
Easy Air-Gap Adjustment: The circular center post allows for straightforward grinding or insertion of gap spacers, enabling precise adjustment of inductance—especially useful for flyback transformers or PFC inductors.
Support for Multiple Windings: The generally wide window area can accommodate multiple secondary windings, making it suitable for multi-output power supplies.
Summary of Pros and Cons Advantages:
Good winding manufacturability and strong production consistency.
Superior heat dissipation and higher power density.
Symmetrical magnetic path, low leakage inductance, and good EMI performance.
High cost-effectiveness in the medium power range (50 W–150 W). Disadvantages:
Compared to some planar cores or smaller RM types, its height is greater, which is not conducive to ultra-thin designs.
For very low-power applications (<20 W), it may be overly large and less economical.
The core requires dedicated clips or tape for fixation, whereas EE cores can sometimes be secured directly with tape.
ETD29 Transformer Core Features The ETD29 is a classic core widely used in switching power supplies, known for its distinct characteristics centered around "high efficiency" and "ease of use." I. Structural Advantages (Physical Features)Circular Center Post:
Key Advantage: This is the most iconic feature of the ETD series. Compared to square center posts, it offers exceptional space utilization during winding. The coil can be packed more densely, making it particularly beneficial for multi-strand parallel winding or Litz wire to reduce high-frequency skin effect losses.
Manufacturing Friendly: In automated winding processes, the circular bobbin and center post enable smoother winding movements, ensuring high production consistency and yield rates.
Symmetrical Magnetic Circuit:
Composed of two identical "E" cores joined face-to-face, the magnetic field distribution is highly symmetrical.
The resulting benefits include lower leakage inductance, which helps improve efficiency and reduce electromagnetic interference.
Excellent Thermal Design:
The cylindrical coil has a large contact area with the core, allowing heat to transfer quickly from the coil to the core.
The core itself offers a large surface area, facilitating heat dissipation into the surrounding air. This structural design typically results in better temperature rise performance compared to EE/EI cores of similar size.
II. Electrical Performance FeaturesPower and Frequency Adaptability:
Typical Power Range: Suitable for switching power supplies in the 50W–150W range, making it a "sweet spot" choice for medium-power applications.
Excellent High-Frequency Performance: Designed specifically for high-frequency operation, with controllable core losses and maintained efficiency at frequencies ranging from 50kHz to 200kHz and even higher.
High Power Density:
The product of effective cross-sectional area and window area is relatively large, meaning it can effectively handle both magnetic flux and current within a compact volume, achieving high power density.
Design Flexibility:
Easy Air-Gap Adjustment: The center post can be easily ground or fitted with gap spacers to precisely adjust inductance, making it ideal for flyback transformers or PFC inductors requiring energy storage or filtering.
Multi-Winding Support: The generous window area allows for multiple secondary windings, simplifying the design of multi-output power supplies.
III. Application and Economic FeaturesWide Application Range:
Regarded as an industrial standard component, it is extensively used in AC-DC adapters, LED drivers, communication power supplies, and industrial control power supplies.
Cost-Effective:
In the low-to-medium power range, it achieves an excellent balance of performance, cost, and availability, making it a highly cost-efficient choice.
ETD29 Application Scope With its medium-power capability, excellent high-frequency performance, and superior thermal characteristics, the ETD29 has a well-defined and broad application positioning in the field of power electronics. Its primary uses are as follows: I. Core Application Area: Switching Power SuppliesThis is the most prominent and classic application stage for the ETD29, as it is almost exclusively designed for high-frequency switching power supplies. AC-DC Power Supplies
Desktop/Industrial Computer Power Supplies: Often used in auxiliary standby power circuits to provide voltages like +5VSB, with a well-matched power range (~30W).
Medium-to-Small Power Adapters: Such as external power supplies for networking equipment, security devices, and office/printing equipment, typically in the 60W–100W range.
Internal Power Modules for Industrial and Communication Systems: Provides isolated DC voltages for chips, relays, drivers, and other components on boards.
DC-DC Power Modules
Used in communication base stations, servers, and new energy systems to convert bus voltages into various low-voltage isolated power supplies.
Commonly applied in topologies like half-bridge, full-bridge, and forward converters to achieve high power density conversion.
LED Driver Power Supplies
Widely used in commercial, industrial, and outdoor lighting applications (e.g., floodlights) with power ratings around 50W–100W. Its excellent thermal performance is crucial for the long lifespan of LED drivers.
II. Specific Functional CircuitsBeyond serving as the main power transformer, the ETD29 is also utilized in specific functional units due to its characteristics. Power Factor Correction Circuits
In boost-type PFC circuits, the ETD29 is often used as the PFC storage inductor. Its circular center post facilitates the creation of large air gaps for substantial energy storage, while its low-loss characteristics suit high-frequency operation.
Isolated Driving and Signal Transmission
In scenarios requiring high-power switching signal transmission (e.g., IGBT/MOSFET isolated gate drivers), the ETD29 can be used to construct isolated drive transformers, ensuring fast, reliable, and strong driving capabilities.
III. New Energy and Industrial FieldsPhotovoltaic/Energy Storage Systems Electric Vehicle Charging Equipment Industrial Automation Equipment |
