Content last revised on March 10, 2026
VHF28-12IO5 IXYS 1200V 28A Half-Controlled Bridge Rectifier
The VHF28-12IO5, a high-performance half-controlled bridge rectifier from IXYS (a Littelfuse company), integrates planar passivated thyristors and diodes into a single ECO-PAC 1 package to offer superior power density and long-term reliability. Featuring a blocking voltage of 1200V and an average on-state current of 28A, this module serves as a critical building block for space-constrained industrial power electronics. It effectively eliminates the need for discrete component assemblies, reducing parasitic inductance and simplifying thermal management in sensitive drive systems. For engineers prioritizing system integration, the VHF28-12IO5 provides a robust, pre-configured solution for AC-to-DC conversion with controlled output capabilities. For 690V line systems requiring significantly higher current handling, the related VUB72-16NO1 provides a three-phase integrated alternative.
Application Scenarios & Value
Optimizing Space and Efficiency in Industrial Motor Control
Engineers often face the challenge of designing compact motor soft starters and battery chargers where thermal headroom is limited and PCB real estate is at a premium. The VHF28-12IO5 addresses this by utilizing the ECO-PAC 1 package, which allows for direct mounting on a heatsink while maintaining high isolation levels. In a typical motor drive input stage, the 1200V rating provides the necessary safety margin for 400V–480V AC lines, protecting against transient voltage spikes. The integrated freewheeling diode is particularly valuable when driving inductive loads, as it prevents high-voltage back-EMF from damaging the switching elements. By consolidating the bridge into a single module, engineers can achieve a lower total cost of ownership (TCO) through reduced assembly steps and improved reliability compared to multi-discrete designs. For simpler rectification tasks not requiring thyristor control, the MDD95-12N1B offers a high-current diode-only configuration.
Technical Deep Dive
Planar Passivation and the ECO-PAC 1 Advantage
At the core of the VHF28-12IO5 is planar passivation technology. Think of planar passivation as a microscopic, high-integrity "security shield" applied to the edges of the silicon die. This process ensures that the electric field distribution remains uniform across the semiconductor junction, preventing localized dielectric breakdown and ensuring that the 1200V blocking capability remains stable even under high-temperature operation ($T_{vj} = 125^circ C$). This stability is crucial for avoiding leakage current "runaway" in industrial environments where environmental noise is prevalent. Furthermore, the ECO-PAC 1 package utilizes a copper base plate for optimized heat dissipation, achieving a junction-to-case thermal resistance (Rthjc) of 1.1 K/W for the thyristor chips. This low thermal resistance acts as a "wider highway" for heat, allowing the module to maintain its 28A rating at a case temperature of 85°C. Understanding these parameters is essential for precise thermal modeling; more insights can be found in our guide on why Rth matters for power modules.
Key Parameter Overview
Decoding the Specs for Integrated Rectifier Performance
| Functional Category | Parameter Definition | Value (Official) |
|---|---|---|
| Voltage Ratings | Max. Reverse/Forward Blocking Voltage ($V_{RRM}/V_{DRM}$) | 1200V |
| Current Capacity | Average On-state Current ($I_{TAV}$) @ $T_C = 85^circ C$ | 28A |
| Surge Performance | Max. Non-repetitive Surge Peak Current ($I_{TSM}$) @ 10ms | 300A |
| Thermal Management | Thermal Resistance Junction to Case (Thyristor) | 1.1 K/W |
| Mechanical Data | Package Type & Isolation Voltage | ECO-PAC 1 | 3000V AC |
Download the VHF28-12IO5 datasheet for detailed specifications and performance curves.
Frequently Asked Questions
Engineering Insights for Field Implementation
How does the 1200V rating of the VHF28-12IO5 improve reliability in 400V AC systems?
In 400V systems, the peak voltage is approximately 565V. A 1200V rating provides a safety factor of over 2x, allowing the VHF28-12IO5 to absorb transient line disturbances without reaching the breakdown region, which is a common cause of premature semiconductor failure. Detailed strategies for preventing such failures are discussed in our resource on IGBT failure analysis.
Can the VHF28-12IO5 handle high-inrush loads during motor startup?
Yes, the module is rated for a surge peak current ($I_{TSM}$) of 300A for a 10ms duration. This allows the VHF28-12IO5 to withstand the temporary inrush currents typical of inductive motor loads without degradation, provided the junction temperature remains within the specified limit.
What is the primary benefit of the ECO-PAC 1 package's direct-mount design?
The ECO-PAC 1 package features a baseplate that can be directly screwed onto a heatsink, maximizing heat transfer efficiency. This eliminates the thermal interface variations associated with discrete bridge assemblies and allows for a more compact UPS or industrial drive design by reducing the physical footprint of the input stage.
For procurement professionals and design engineers seeking reliable input stage solutions, our technical sales team is available to assist with volume inquiries and technical documentation. Request pricing now to secure the components needed for your next-generation power conversion project.
