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ADUM 4221 and miximum duty cycle and power supply of the high side

Category: Hardware
Product Number: ADUM4221-1ARIZ

Hello can you help us, we have some trouble around the functionning of the driver ADUM4221-1ARIZ !

This is our schematics we are actually using this driver with max duty of 90% of our PWM (30Khz), but we want to go to 100% of our PWM but we know that is we use a bootstrap it's not possible. So we decided to remove the bootstrap and add two DC/DC one for the High side (gnd_A) and the other one for the High side (gnd_b) and one for the two low side, but when we test this new functionnality the driver burn. Do you have some idea why our new functionnality was not working well !

Thanks you a lot

  • Hi Michael,

    Thanks for using the ADuM4221 in your design.

    In the schematic, I can only see the Bootstrap circuit and not the DC/DC that you mentioned.

    May I know how you implemented the DC/DC regulator that supplies the secondary side of the ADuM4221? Is the DC/DC regulator for high side and low side isolated with each other? Where is the power from the DC/DC coming from - Primary side or Secondary Side?

    Thanks and regards,


  • Hello Jeco,

    Thank you for your help !

    We actually using with the bootstrap but we want to test the ADUM4221 without bootstrap to go to 100% of our PWM, so we just make a prototype and remove R4/D2 and R5/D3 and add one DC/DC converter for each high side of the driver to power up each side individually (as you can see on the picture)

    but when we start our new prototype the driving failed after 1/2 seconds and burn the driver

  • Hi Michael,

    correct me if I'm wrong, you tied the low side supplies to a single +12V supply and you add 2 more 12V supplies to supply each of the 2 High-Side drivers.

    Does the High-side and Low-side 12V supplies for each Leg were isolated with each other? Your 3 supplies need to be isolated with each other.

    Where are the 12V supply powered from? Did you try checking the GND connections of your 3 12V supplies to see if they are all isolated with each other?

    Thanks and regarrds,