Gate-Driver ADUM4221

Hi Patty,

Thanks for your interest in using the ADuM4221. I can see that your supplies V1 and V2 are referenced to common GND which cause the issue. You should reference your V1 to GNDA (MW_O) so that your high-side FET will see the full 12V gate driver voltage. Same as with V2, the ground connection should be connected to GNDB or MW_U.

I'm not sure if your are aware of this, but there we example of basic circuit of each of the part if you navigate to your LTspice folder --> example --> Applications as shown below.

Let me know if you require further assistance.

Best regards,

Jefferson

Dear Jefferson,

I want to express my gratitude for your prompt response and the valuable recommendation you provided. I made adjustments to my LTspice circuit, and the simulation now functions significantly better. This has enabled me to successfully control the high-side MOSFET.

I also managed to locate example circuits within the data path, but I am currently using the Gate-Driver as depicted in the attached images.

However I am using the Gate-Driver in the following as shown in the pictures: 

However, I noticed in the datasheet for the ADUM4221, they illustrate a bootstrap circuit. Is this bootstrap circuit necessary for controlling the high-side MOSFETs, or can I achieve the same control of the half-bridges as shown in my LTspice circuit?

I've included the datasheet circuit for your reference. My ultimate goal is to control a full-bridge circuit composed of these half-bridges.

Thank you once again for your assistance.

Sincerly,
Tahir 

Hello Tahir,

Great to read that your circuit is already working. Just take note of the GNDx connections in your actual implementations.

For the bootstrap recommendation - it is just a recommendation if you like to power the secondary side of the gate driver with a single power supply (VDDB from Figure 38). 

However, if you have means to provide an isolated power supplies for the high-side gate drivers separately - this is absolutely okay (same as with the LTspice circuit you provided).

Let me know other concerns you have and I'm happy to help.

Best regards,

Jefferson

Hello Jefforson, 

I have one last question. I am using this Gate-Drive for the STP65N150M9  N-Channel MOSFET. 
Do you see any problem for using this Gate-Driver for this MOSFET type. 
The MOSFET has a total gate charge of 32 nC.

Best regards, 

Tahir  

Hello Tahir,

I don't see any problem for the ADuM4221 driving STP65N150M9 N-Channel MOSFET.

The question is how fast you want the MOSFET to switch ON/OFF (which is a factor of your switching loss budget). This is where you need to compute for the gate current drive requirement for the given gate charge and rise/fall time you want the MOSFET to switch (IG = QG / rise time or fall time).

And then you can compute for the total gate resistance to be able to meet your IG requirement.

Thanks and regards,

Jefferson