EPC GaN transistors support 4kW buck-boost reference design

Efficient Power Conversion has confirmed that its EPC2361 gallium nitride transistors are used in Analog Devices’ EVAL-LT7930-AZ buck-boost converter reference design. The dual-phase platform regulates a 48V output from a supply ranging between 36V and 65V, with maximum output power specified at 4kW.

EPC announced the component application on 20 October 2026, identifying its 100V enhancement-mode GaN field-effect transistors as switching devices in the reference circuit. Analog Devices had already published the evaluation-board documentation in July, so the October development concerns EPC’s identification of the device application rather than the first availability of the complete board.

The EVAL-LT7930-AZ combines two LT7930 controllers in a parallel, interleaved converter architecture. Each controller manages a four-switch buck-boost power stage, allowing the output to remain regulated as the input voltage moves above, below or close to the required 48V level. This operating range is relevant to battery-backed DC supplies, telecommunications equipment and industrial power systems.

Unlike a basic buck converter, which reduces voltage, or a conventional boost converter, which raises it, a four-switch buck-boost circuit can operate in both regions. The controller changes how energy is transferred through the power stage according to the relationship between the input and output voltages.

An inductor provides the energy storage needed during switching. When the relevant semiconductor devices conduct, current changes through the inductor and energy is transferred between the input and output networks. The control system regulates the switching sequence to maintain the required output while responding to changes in supply voltage and load.

The LT7930 uses a constant-frequency peak current-mode control architecture. Inductor-current information contributes to the switching decisions, while output-voltage feedback establishes the regulation requirement. The controller also provides programmable average input or output current regulation, allowing a suitable implementation to manage charging or load current within defined limits.

Operating across the boundary between buck and boost regions requires careful coordination of the semiconductor switches. A converter may encounter the target output voltage as its input passes through 48V, and the control scheme must avoid unnecessary disturbances while changing its operating sequence. Analog Devices specifies continuous regulation through that transition.

The evaluation board contains two converter phases operating at 150kHz, with their switching patterns offset by 180 degrees. This interleaving arrangement spreads the energy-transfer events across the switching period instead of making both phases operate in synchronisation.

Interleaving can reduce selected ripple components in the combined input or output current. When the phases produce current variations at different points in the switching cycle, part of their ripple can cancel. The actual cancellation depends on operating duty cycle, phase balance, inductor values and the currents carried by the individual stages.

Sharing the load between two phases can also distribute electrical and thermal stresses across additional components. The control system must maintain suitable current sharing, however, because component tolerances or differences in switching behaviour can cause one phase to carry more current than the other.

Each phase uses EPC2361 enhancement-mode GaN transistors in the switching network. EPC specifies a 100V drain-source rating, typical on-resistance of 0.75 milliohms and a package measuring approximately 3mm by 5mm. These characteristics are relevant to high-current conversion because conduction losses rise with the square of current passing through a resistive element.

Low on-resistance can reduce losses while a switch is conducting, although the full electrical path also includes inductors, copper tracks, electrical connections and other components. At high output current, resistance elsewhere in the circuit can contribute meaningful heat even when the main power semiconductor has comparatively low conduction loss.

Switching introduces a separate loss mechanism. During a transition, a device may briefly support voltage and current simultaneously, while energy is also required to charge and discharge internal capacitances. GaN devices can offer advantages in suitable high-frequency designs because of their switching characteristics, but the realised benefit depends on gate-drive timing, circuit layout and the surrounding power stage.

The fast voltage and current transitions associated with GaN technology also make parasitic inductance important. Inductance in the switching loop can produce voltage overshoot and ringing, particularly when current changes rapidly. Semiconductor placement, conductor geometry and connections between the power devices and decoupling capacitors are therefore important elements of the electrical design.

Gate-drive arrangements must prevent unwanted simultaneous conduction through complementary switching devices. The LT7930 provides gate drivers optimised for 5V operation and resistor-programmable dead time, allowing switching intervals to be configured for the devices used in the power stage.

Dead time separates switching events to reduce the risk of current flowing directly through opposing devices. Too little margin can create destructive conduction paths, while excessive dead time can increase losses or alter the behaviour of the switching stage. The appropriate setting depends on device characteristics, propagation delays and the measured behaviour of the assembled converter.

Thermal design remains necessary even when conversion efficiency is high. A multi-kilowatt supply can dissipate substantial power through its semiconductor devices, magnetic components and conductors. Cooling requirements depend on the distribution of these losses and the thermal conditions inside the installed equipment.

EPC reports typical efficiency of approximately 98.5% at input voltages of 36V and 48V, rising to 98.8% at 65V under the conditions used for its announcement. Analog Devices separately specifies efficiency above 98% at 3kW output across the board’s rated input-voltage range.

Those figures describe different reported operating conditions and should not be combined into an assumed efficiency rating at the maximum 4kW output. Efficiency can vary with load, input voltage, component temperature and switching conditions, so a full performance assessment requires measurements across the operating envelope relevant to the intended application.

At the specified maximum output of 4kW and 48V, the output current would be approximately 83A. Such current levels place considerable demands on connectors, PCB copper, magnetic components and current-sensing arrangements. The reference hardware must also manage the changes in supply-side current that occur as the input voltage varies.

Protection is another consideration. A practical industrial power supply must respond appropriately to excess current, abnormal input conditions and thermal faults. The controller provides functions that can support these responses, but the complete system’s protective behaviour depends on component selection, configuration and the surrounding hardware.

Analog Devices supplies evaluation-board design files, schematic information and supporting technical documentation. These resources allow engineers to study the converter arrangement and assess its suitability as a starting point for application-specific equipment. They do not establish that the board is a fully qualified replacement for every industrial, telecommunications or battery-charging installation.

The application also differs from EPC’s earlier work on 800V distribution architectures for data centres. The EVAL-LT7930-AZ is intended to regulate around a 48V DC supply, with a 36–65V input range and a two-phase four-switch topology. Its disclosed operating points provide a basis for evaluating GaN conduction losses, switching behaviour, interleaving and thermal performance at several kilowatts.