How to drive an E mode GaN FET by ADuM4221-1A

Question

Hi ADI's experts： 
 I'm about to use an E mode GaN FET: GAN3R2_100CBE, as attachment. can I use ADuM4221-1A to drive it? Any caution or design references to take? especially the gate drive circuit, thank a lot! 
 because my design is about to use an floating design, so an isolated half bridge gate drivers is needed. 
 PDF

AAlessandro · Accepted Answer

Hi Shawn_Tao , 
 yes, the ADuM4221-1 is designed to drive this kind of switches. In particular, you should use the grade-A, the one with the UVLO at 4.5V. 
 This is the complete gate driver schematic. In detail we have: 
 
 R2/R5 - gate resistor: This allow you to shape the rise/fall time. The resistors should be picked in order to have a good trade-off between transition speed and over/under shoot, which must not be higher than the switches' AMR (6V in your case, pag. 3). In some design is possibile to find this diode + resistor in parallel with the gate resistance providing the current two different paths for rise and fall transitions. This is usually done to match the rise and fall time, tuning the R8 value. The diode should be able to take 4A peak current, I suggest you to use this part number: CDBU0245-HF 
 C3-R7/C2-R3 - RC Snubber: this is not mandatory but it could help reducing the ringing 
 R4/R6: resistor that helps keeping the switch off. R should be ~10k-100k 
 
 You will have also to power the secondary sides, I suggest you to check this resource: 
 https://www.analog.com/en/resources/technical-articles/powering-the-isolated-side-of-your-half-bridge-configuration.html 
 
 For what concern the PCB layout, here some tips: 
 
 keep your gate driver loops small, any line that is in series with an inductor can be long, any traces in parallel with a capacitor should be short 
 keep in mind the creepage between high and low side 
 place decoupling capacitors close to the pin 
 
 I suggest you to check the APPLICATIONS INFORMATION in the datasheet to size the Resistor for the dead time control and some tips on the PCB layout 
 
 here another link for measuring the waveform: 
 https://www.analog.com/en/resources/media-center/videos/5771266874001.html 
 This information should be enough for starting your design. 
 If you have additional question, you are free to ask! 
 Alessandro)

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How to drive an E mode GaN FET by ADuM4221-1A

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