ST Expands MasterGaN Portfolio to Simplify 45W and 150W Designs

September 04, 2021 by Ikimi .O

MasterGaN integrates GaN transistors and half-bridge gate drivers on a single chip. Now, the family has grown to support higher-efficiency technology.

Due to higher demand for smaller and more efficient charging solutions, STMicroelectronics recently added to its existing MasterGaN platform (MasterGaN1, 2, and 4) with MasterGaN3 and 5. These solutions incorporate GaN transistors with gate drivers in a single, compact package designed for advanced power applications.


MasterGaN3 and 5

MasterGaN3 and 5. 

How exactly do these new MasterGan releases size up to previous iterations? 


Overview of the MasterGaN Platform

STMicroelectronics’ MasterGaN platform is a high power density half-bridge system that integrates GaN transistors and half-bridge gate drivers into a single package. The company’s choice of gallium nitride (GaN) transistors translates into higher operating frequency, power, and efficiency in power electronics.

Compared to standard silicon-based transistors, GaN transistors offer a lower gate charge, output capacitance, and reverse recovery charge, which lowers switching losses and achieves higher frequency and efficiency. GaN transistors also deliver high critical electric fields due to their comparatively higher electron mobility. This also enables a more compact size with a high breakdown voltage. 


GaN transistors and Si MOSFETs

Graphical comparison between the features of GaN transistors and Si MOSFETs. 


Common challenges with conventional GaN transistors include complex gate drive design and PCB layout limitations. STMicroelectronics says it addresses these limitations with its MasterGan portfolio, achieving simpler gate drive circuits and layout designs.


Design Considerations of MasterGaN

ST has designed its MasterGaN solutions for a wide range of applications, including solar DC-AC converters, energy storage systems, high-density AC-DC adapters, telecommunication, electrical vehicle charging stations, computer powering, power supply for 5G communication infrastructure, and many more.

The company says these transistors offer simplified circuit layouts, reduced bill of materials, scalable pin-to-pin solutions, and compactness. The MasterGaN low- and high-side undervoltage lockout (UVLO) protection is said to prevent design malfunction by shutting down during large voltage drops and resetting after recovery.


Integrating the Platform Into Designs

With the integrated chips, designers will not need to figure out the most suitable way to use standalone gate driver ICs in GaN transistor-based applications. 


Application diagram of an active clamp flyback

Application diagram of an active clamp flyback. 

Because of the solutions’ wide operating temperature range (-40°C to 125°C), engineers can incorporate them into a range of temperature-sensitive power electronics. Their compact QFN package also allows engineers to develop miniaturized devices with frequency and clock rate benefits.

ST also says MasterGaN has extended input pins that can easily connect with microcontrollers and digital signal processor (DSP) units for efficient design functioning.


Common Ground of MasterGaN 1, 2, and 4

MasterGaN1, MasterGaN2, and MasterGaN4 target 45 W to 400 W applications, which may be useful in switched-mode power supplies, adapters, chargers, and DC/DC converters. A comprehensive look at their specifications shows that they exhibit various similarities, including: 

  • Drain-source blocking voltage of 650 V
  • Compact QFN 9 x 9 mm2 package
  • Reverse current functionality
  • Zero reverse recovery loss
  • Interlocking functionality
  • Low- and high-side UVLO protection 
  • Shut down functionality with a dedicated pin
  • Compatible input voltage range of 3.3 V to 15 V
  • Over-temperature protection capability
  • Bootstrap diode incorporation
  • Industrial operating temperature range (-40°C to 125°C)

However, there are several distinctions among these MasterGaN iterations. While the MasterGaN 2 incorporates two drain-source on-resistance (RDS(ON)) for its low and high side, the other two in the series incorporate only one. RDS(ON) values for the MasterGaN series are 150 mΩ for MasterGaN 1, 150 mΩ (LS) + 225 mΩ (HS) for MasterGaN2, and 225 mΩ for MasterGaN3. 


MasterGaN version

A breakdown of the different design applications associated with each MasterGaN version. 


Another notable difference between these solutions is their drain current (IDS(MAX)), with MasterGaN 1, 2, and 4 having 10 A, 10 A (LS) + 6.5 A (HS), and 6.5 A values, respectively. Engineers can take advantage of these solutions’ interlocking functionality to design power electronics with minimized cross-conduction conditions. The UVLO capabilities in lower and upper driving sections are also essential to avoiding low-efficiency power switching in designs.


Latest Additions to the MasterGaN Platform

STMicroelectronics recently added MasterGaN3 and 5 to its MasterGaN series. The new additions should ease the transition to higher-efficiency technology. Further supporting the migration from silicon MOSFETs to GaN, these latest MasterGaN solutions aim to provide a more robust and reliable power supply than silicon-based solutions in over 80 percent smaller packages.


Block diagram of MasterGaN3

Block diagram of MasterGaN3.

The company designed the MasterGaN3 solution for soft-switching applications with its asymmetrical RDS(ON) of 225mΩ and 450mΩ. MasterGaN5’s 450mΩ value is, however, geared for applications requiring active clamp flyback and LLC-resonant topologies. 


Block diagram of MasterGaN5

Block diagram of MasterGaN5.


Although the two new additions share similar specifications with older MasterGaN solutions—such as UVLO protection, gate-driver interlocking, extended input pins, and input voltage range—they come in a GQFN package for high-voltage applications.

STMicroelectronics has also developed two new dedicated prototype boards, EVALMASTERGAN3 and EVALMASTERGAN5 to support engineers in their MasterGaN3 and MasterGaN5-based design processes. With the extra support, they can generate driving signals for the two chips, add an external bootstrap diode, insert a low-side shunt resistor, and apply input signals.


All images used courtesy of STMicroelectronics.