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# ADUM4221 - High-Side isolation to GND and maximum Dutycycle

Hi,

I want to use the ADUM4221 to control a H-Bridge with V_Bus = 110 V and V_DDB = 15 V with bootstrapping circuit as in the attached incomplete schematic.

Now I am not sure if the voltage of V_DDA = 125 V refer to GND_SEC is ok, because you write in datasheet (link below) under ELECTRICAL CHARACTERISTICS: "... high-side voltages referenced to GNDA, GNDB, ..." and under ABSOLUTE MAXIMUM RATINGS: "VDDA and VDDB −0.3 V to +40 V".

Is that possible?

An additional question is the possibility to drive the right side of the H-Bridge (see in schematic) with 100 % Dutycycle?

Thanks a lot.

www.analog.com/.../technical-documentation/data-sheets/adum4221_4221-1_4221-2.pdf

• Hello,

The ADuM4221 can be thought of as three separate isolation regions. There is one region that comprises pins 1-8, which we often call the primary side. The two other regions are pins 9-11, and pins 14-16. We call these two the secondary sides, or region B and region A.

The isolation between region A and region B is a functional isolation that can support hundreds of volts. There isn't a specific number given for this, as it is not a safety isolation. A bus voltage of 125 V is well within the capabilities of the part. The bus voltage shows up across region A and region B. The allowable voltage differential between region A and region B is usually constrained by the creepage distance between pins 11 and 14 (minus pins 12-13). This allows for hundreds of volts.

Within each region A and region B, the VDD voltages have a maximum of 40 V. This refers to the pins VDDA to GNDA, and separately, the voltage between VDDB and GNDB. This is because region A sits on one piece of silicon, and region B sits on a separate piece of silicon. Each of these pieces of silicon are done in a 40 V process, allowing us to power them individually to 40 V. The two pieces of silicon are allowed to be separated by hundred of volts due to our isolation technology, allowing for much higher bus voltages.

In summary, yes, the ADuM4221 will work well in your application.

RSchnell