Content last revised on June 26, 2026
VHF28-16IO5 Single-Phase Half-Controlled Rectifier Bridge
The VHF28-16IO5, manufactured by IXYS (a Littelfuse company), is a high-performance single-phase half-controlled bridge rectifier designed for precise power regulation in space-constrained industrial environments. Featuring 1600V peak repetitive reverse voltage and an output current of 28A, this module integrates planar passivated chips into the compact ECO-PAC1 package. For 480V input phase-controlled heaters requiring a compact footprint and 1600V isolation, the VHF28-16IO5 is the optimal choice.
Application Scenarios & Value
Achieving Precision and Reliability in Phase-Controlled Industrial Loads
Engineers often face the challenge of balancing circuit complexity with thermal robustness when designing compact power controllers. The VHF28-16IO5 simplifies this by combining thyristors and diodes in a single-phase bridge configuration, specifically optimized for applications like DC motor speed control and industrial resistive heating. In a typical welding power supply or battery charging stage, the 1600V blocking capability provides a necessary safety margin against line transients and inductive kickback.
Consider an industrial conveyor system utilizing a DC shunt motor. The VHF28-16IO5 facilitates smooth torque regulation through phase-angle control. Its integrated freewheeling diode is a critical design advantage; by providing a dedicated path for inductive current when the thyristors are commutated, it prevents voltage spikes that could otherwise degrade the semiconductor structure over time. For systems requiring three-phase input rectification rather than single-phase, the VUB72-16NO1 offers a higher current handling and a similar 1600V rating in a specialized PIM configuration.
Technical & Design Deep Dive
Thermal Architecture and Package Innovation in the ECO-PAC1
The internal construction of the VHF28-16IO5 utilizes planar passivated chips to ensure long-term parameter stability and low leakage currents. The ECO-PAC1 package is engineered for direct PCB mounting with solderable terminals, significantly reducing stray inductance compared to traditional screw-terminal modules. This is vital for maintaining EMC compliance in fast-switching phase control circuits.
A decisive engineering metric for this module is its isolation voltage, rated at 3000V~. To understand the significance of the 1.45 K/W thermal resistance (junction-to-case), consider the thermal path like a high-capacity drainage pipe in a plumbing system. Just as a wider pipe prevents water backflow during a storm, the low Rth(j-c) ensures that heat generated during high-current conduction is "flushed" away from the silicon die to the baseplate and heatsink before thermal runaway can occur. Furthermore, the inclusion of a Kelvin Emitter-like configuration for the gate-cathode connections ensures that the firing pulses remain clean and immune to the noise generated by the high-current power path.
Key Parameter Overview
Decoding the Specs for Enhanced Power Density
| Feature/Parameter | Specification Value | Engineering Significance |
|---|---|---|
| V_RRM / V_DRM | 1600V | High voltage overhead for 480V/600V AC line stability. |
| I_dAV (Tc = 85°C) | 28A | Rated for continuous industrial duty cycles. |
| V_ISO (Isolation) | 3000V~ | Ensures operator safety and compliance with IEC 61800-3. |
| V_T / V_F (at 15A) | 1.31V / 1.15V | Lower forward voltage reduces total conduction losses. |
| I_TSM (10ms surge) | 200A | Robustness against downstream short-circuits or inrush. |
Download the VHF28-16IO5 datasheet for detailed specifications and performance curves.
Frequently Asked Questions
What is the primary benefit of the integrated freewheeling diode in the VHF28-16IO5?
The integrated diode protects the thyristor arms from high-voltage transients when driving inductive loads, such as solenoids or motors, by providing a safe path for current decay during the "off" state.
How does the 1.45 K/W Rth(j-c) impact the choice of heatsink for a 20A application?
With a total forward voltage drop of approximately 1.3V, a 28A load generates significant heat. The 1.45 K/W resistance dictates that the heatsink must be capable of maintaining the case temperature below 85°C to prevent the junction from exceeding the 125°C maximum limit.
Is the VHF28-16IO5 suitable for pulse-width modulation (PWM) control?
No, this is a thyristor-based phase-controlled module. It is intended for line-frequency phase-angle control (50/60Hz) rather than high-frequency PWM, which would require an IGBT or MOSFET based solution.
Does the ECO-PAC1 package support automated assembly?
Yes, the solderable pins and standardized height of the ECO-PAC1 package are designed for wave soldering on PCBs, enabling faster production cycles compared to manual-wired modules.
From a strategic infrastructure perspective, the VHF28-16IO5 represents a shift toward higher integration at the edge of power electronics. As global energy standards drive the demand for more efficient variable frequency drives (VFD) and smart heaters, the reliability of the input rectification stage becomes the foundation of system longevity. Integrating advanced planar passivation ensures these modules meet the 10-year reliability targets required by modern heavy industry 4.0 standards.
