Custom EE25 Ferrite Core Transformer For Industrial LED Driver Power

The EE25 is a high frequency switching transformer built on an EE25 ferrite core with a vertical PCB-mount bobbin, designed to transfer power across an isolation barrier inside compact switch mode power supplies. It receives the chopped high frequency waveform from a flyback or forward converter stage, converts it to the required secondary voltage, and maintains full galvanic isolation between the primary mains side and the low voltage output. The unit shown carries the CHIPSEN marking with UL file number E332338 and part code EE25-102-13616.

An EE25 is not a scaled-down mains transformer. Because it operates at tens to hundreds of kilohertz instead of 50/60 Hz, the design is governed by core loss, leakage inductance and winding capacitance rather than by copper cross-section alone. Turns ratio, primary inductance, layer sequence and insulation barriers are all defined by the converter topology it serves, which is why this size is normally built to a customer schematic rather than selected from a catalogue.

The EE25 core size sits in the practical middle ground between board area and deliverable power. It provides enough winding window for reinforced insulation and multiple secondary rails, while still fitting the height and footprint budget of adapters, LED drivers, industrial instrument supplies and auxiliary rails inside larger equipment. Below this size the window becomes too tight for safety spacing on universal mains input; above it the component begins to dominate the board.

Electrical values are project specific. Send the converter topology, switching frequency, input range, output rails and target output power, and our engineering team will return a wound sample specification with confirmed inductance, turns ratio and pin-out.

• Compact vertical footprint. The vertical bobbin keeps board area small and places all pins on one plane, suited to wave soldering and selective soldering lines.
• Full galvanic isolation. Primary and secondary windings are separated by a defined insulation barrier, so the low voltage output stays safely referenced away from the mains side.
• Controlled gap for flyback duty. The core can be supplied with a defined air gap to set primary inductance and keep the core out of saturation under peak current.
• Low core and copper loss construction. Wire gauge, layer sequence and winding split are chosen to limit skin and proximity effect at the intended switching frequency.
• Reinforced insulation option. Margin tape or triple insulated wire construction is available where the end product must meet reinforced isolation requirements.
• Multi-output capability. The winding window accepts multiple secondary rails plus an auxiliary bias winding within the same EE25 body.
• Flexible pin-out. Pin count and pin assignment follow your PCB layout instead of forcing a layout change.
• Repeatable production quality. Automated winding with in-process electrical testing keeps inductance and turns ratio consistent across production batches.
• Traceable marking. Each unit is labelled with the part code and UL file number for incoming inspection and audit traceability.

• Switch mode power supplies and AC-DC adapters
• LED driver and lighting control power stages
• Industrial control and instrumentation auxiliary supplies
• Battery chargers and small inverter power conversion
• Communication and networking equipment power modules
• Home appliance and building automation control boards
• Security, metering and IoT device power sections
• Auxiliary bias supplies inside larger industrial equipment

• 26 years of magnetics focus. DongGuan Chipsen Electronics Technology Co., Ltd. was established in 2000 and has concentrated on custom transformers and inductors for industrial and power electronics customers ever since.
• Owned manufacturing base. Production runs on 8 complete lines inside a 10,000 sqm owned facility, not a rented workshop, with an annual transformer output of approximately 2,400KK pcs.
• In-house engineering and quality teams. A 20-person R&D team and a 20-person QC team support each project from prototype through mass production.
• Complete certification system. ISO 9001 and ISO 14001 management systems, with CE, CB, UL / cUL and RoHS at product level.
• Proven export record. Long-running supply to North America, South America, Northern Europe and Southeast Asia, including industrial equipment and inverter manufacturers.
• Direct factory communication. You talk to the engineers who design and build the part, which shortens the loop between a specification change and a corrected sample.

• Designed to your circuit, not adapted to it. Turns ratio, inductance, gap and pin-out are set from your schematic, so the transformer matches the controller and topology you already selected.
• Insulation designed for the target standard. The isolation structure is defined against the safety standard your end product must pass, rather than applied as a generic build.
• Thermal margin built in. Wire gauge and insulation class are selected with headroom for the enclosure temperature the unit will actually see.
• Consistency across batches. Electrical testing in production keeps key parameters within the tolerance band agreed on the approved drawing.
• Sample before commitment. Engineering samples are wound and verified before mass production release, so the design is proven on your board first.
• Stable supply capacity. Line capacity absorbs volume increases without pushing your delivery schedule out.

Q1: Are you a factory or a trading company?

We are a manufacturer. Our own 10,000 sqm production base in Changping, Dongguan, China runs 8 complete production lines. You are welcome to arrange a factory audit.

Q2: Can you build the EE25 to our own schematic?

Yes, custom design is our core business. Please provide the converter topology, switching frequency, input voltage range, output rails and current, target power, safety standard and PCB pin-out. Our engineers will return a proposed winding structure for your confirmation.

Q3: What is your MOQ?

MOQ is normally 1,000 pcs. For complex custom designs the quantity can be discussed based on tooling and setup requirements.

Q4: Do you provide samples before mass production?

Yes. Engineering samples are wound and electrically verified before mass production is released, so the design can be validated on your board first.

Q5: What payment terms do you accept?

We accept T/T, PayPal and Western Union.

Q6: What trade terms and shipping do you support?

We support DDP and DDU. All goods ship directly from our factory in Dongguan, China. We do not operate overseas warehouses and we do not offer one-piece dropshipping.

Q7: What certifications do you hold?

Management systems: ISO 9001 and ISO 14001. Product level: CE, CB, UL / cUL and RoHS. The unit shown carries UL file number E332338. If your market requires an additional approval, we can review feasibility with you.

Q8: How do you control quality?

Quality management follows ISO 9001. A dedicated 20-person QC team covers incoming material inspection, in-process control and final electrical testing. Every design is verified against the approved drawing before release.

Q9: Can you supply a reinforced insulation version?

Yes. Margin tape construction or triple insulated wire is available depending on the creepage, clearance and isolation level your end product must meet.

Q10: Can you supply other core sizes as well?

Yes. Besides EE series we produce EFD, EPC, PQ and RM type high frequency transformers, plus low frequency transformers, toroidal inductors, SMD inductors and filters. A single order can combine several magnetic components.