Vishay has introduced the IFBT series of surface-mount flyback transformers for isolated power converters operating from a 26 V to 72 V input range at 250 kHz.
The Vishay IFBT MT Flyback Transformers family combines configurable multiple windings with 1500 VRMS isolation, addressing PoE power stages and isolated DC/DC converter designs up to 30 W.
Key features and benefits
- Surface-mount flyback transformer family for compact isolated power-conversion assemblies, with package dimensions starting at 22.0 mm × 17.5 mm × 9.1 mm.
- 17 standard devices spanning 6 W, 13 W, and 30 W power options.
- 26 V to 72 V input operation at 250 kHz, matching a broad range of intermediate-bus and PoE-related converter requirements.
- 1500 VRMS isolation for 60 seconds from the primary and bias windings to the secondary, supporting galvanic separation between input and load domains.
- Multiple windings that can be connected in series or parallel, giving designers options to tailor voltage or current capability to the converter architecture.
- Open construction intended to simplify winding modifications for customer-specific requirements.
- RoHS-compliant construction and a specified operating temperature range from -40 °C to +125 °C.
Technical highlights
The IFBT family covers primary inductance values from 35 µH to 75 µH, with a ±10% tolerance. Maximum peak-current ratings range from 1.1 A to 2.6 A, depending on the part number and power class.
| Parameter | IFBT series range or option |
|---|---|
| Input voltage range | 26 V to 72 V |
| Nominal operating frequency | 250 kHz |
| Isolation | 1500 VRMS for 60 s, primary and bias to secondary |
| Primary inductance | 35 µH to 75 µH, ±10% |
| Output-voltage options | 1.8 V to 24 V |
| Output-current options | 0.5 A to 9.0 A |
| Maximum peak current | 1.1 A to 2.6 A |
| Temperature range | -40 °C to +125 °C |
| Starting package size | 22.0 mm × 17.5 mm × 9.1 mm |
The published standard options cover low-voltage outputs such as 1.8 V, 2.5 V, 3.3 V and 5 V, along with 12 V, 19.5 V and 24 V outputs. This range is relevant where a converter must derive isolated logic, control, communication or load rails from a higher-voltage distribution bus.
Selected 30 W options
| Part number | Primary inductance | Maximum peak current | Nominal output |
|---|---|---|---|
| IFBT0912ABFS303R30 | 42 µH | 2.6 A | 3.3 V / 9.0 A |
| IFBT0912ABFS305R00 | 42 µH | 2.6 A | 5.0 V / 6.0 A |
| IFBT0912ABFS301200 | 42 µH | 2.6 A | 12 V / 2.5 A |
| IFBT0912ABFS302000 | 42 µH | 2.6 A | 19.5 V / 1.5 A |
| IFBT0912ABFS302400 | 42 µH | 2.6 A | 24 V / 1.25 A |
Typical applications
Vishay positions the IFBT transformers for:
- 6 W and 30 W Power over Ethernet designs
- Isolated DC/DC converters up to 30 W
- Automotive lighting LED drivers
- Energy-generation, distribution and management equipment
- Industrial drives, tools and automation systems
- Home and building controls
- Consumer and white-goods electronics
- Telecom equipment
- Medical instrumentation
Application fit
A flyback transformer stores energy in its magnetising inductance while the primary-side switch is on, then transfers that energy to the secondary when the switch turns off. This makes the topology particularly useful for isolated low- and medium-power rails, multiple outputs, and applications where a transformer must also provide safety or functional isolation. For a practical overview of topology operation and magnetic-component requirements, see Flyback Transformer Understanding and Design.
The IFBT winding flexibility can be useful when adapting a standard magnetic platform to an output-voltage or load-current requirement. However, a winding change should be treated as a full magnetic and safety review rather than a simple turns-ratio adjustment, because it can affect leakage inductance, winding capacitance, regulation, peak current, thermal performance and isolation distances.
Design-in notes for engineers
- Verify the operating point. The 26 V to 72 V input range and 250 kHz operating point should be checked against the actual controller frequency, input transient profile and required output-power envelope.
- Select by converter energy requirements, not output voltage alone. Compare the primary inductance, peak-current rating, turns ratio, winding DCR and thermal conditions with the intended discontinuous, critical or continuous-conduction operating mode.
- Account for leakage inductance. Leakage inductance influences drain-voltage overshoot and the energy handled by the clamp or snubber network; its impact should be evaluated with the selected MOSFET, rectifier and PCB layout.
- Check isolation at system level. The stated 1500 VRMS test condition defines transformer isolation performance, but the complete converter must still meet applicable creepage, clearance, insulation-system and end-equipment safety requirements.
- Evaluate winding configuration carefully. Series and parallel winding arrangements can change output-current capability and voltage stress, but they require correct phasing, current sharing and insulation review.
- Validate temperature rise. The specified -40 °C to +125 °C range does not replace transformer temperature-rise testing in the final enclosure, particularly in sealed industrial, telecom, lighting and PoE equipment.
- Qualify custom variants early. Vishay states that the open construction supports winding modifications; designers should obtain the current manufacturer datasheet and documentation for final electrical, mechanical and production qualification.
For circuit-level context, the Flyback Converter Design and Calculation guide provides a useful starting point for relating reflected voltage, duty cycle, primary inductance and switch-current stress.
Further reading
- Flyback Transformer Understanding and Design
- Common Mistakes in Flyback Transformer Specs
- How to design a 60W Flyback Transformer
- USB PD 3.0 Flyback Transformer Optimisation
- Transformers: How Transformers and Solenoids Work
Source
This article is based on the Vishay manufacturer press release and product information for the IFBT series. Engineers should consult the current manufacturer datasheet and supporting documentation for final component selection, qualification and design release.
