Custom EF25 High Frequency Transformer for Flyback SMPS Power
Supply Charger
1.Product Description
The EF25 high-frequency transformer is a compact ferrite core
transformer designed specifically for flyback topologies in switch
mode power supplies (SMPS), battery chargers, and power adapters.
The power range is 10W to 30W, the operating frequency is 20kHz to
200kHz, the performance is stable, the temperature rise is low, and
the efficiency is high. 5+5 pin configuration, inductor voltage
size, and other specifications are fully customizable. Very
suitable for applications with limited space but requiring
reliability and customized specifications.
Application Scenario: 24W USB-C Fast Charger for smartphones and tablets
How the EF25 Transformer Works in This Product:
Inside the charger, the EF25 high frequency transformer is used in
a flyback SMPS circuit. It steps down the high voltage AC
(100-240V) to a low voltage DC (5V, 9V, 12V, or 15V) while
providing isolation for safety. The transformer operates at 100kHz
switching frequency, delivering up to 24W of power (e.g., 12V / 2A
or 15V / 1.6A). Its compact EF25 core size fits perfectly inside
the small USB-C charger housing, while the custom winding ensures
low leakage inductance and high efficiency (>88%), reducing heat
generation during fast charging.
Why Choose the EF25 for This Application:
Small footprint fits slim charger design
Supports multiple output voltages for fast charging protocols
(QC/PD)
Low temperature rise ensures safe surface temperature
Customizable parameters meet specific voltage and current
requirements
2.Performance Characteristics
| Parameter | Specification |
| Core Type | EF25 (Ferrite Core) |
| Topology | Flyback |
| Power Range | 10W – 30W |
| Pin Configuration | 5+5 Pin (customizable) |
| Operating Frequency | 20kHz – 200kHz |
| Hi-Pot Test | 1500V AC / 1min (or custom) |
| Insulation Class | Class B (130°C) / Class F (155°C) optional |
| Compliance | RoHS, REACH |
