ADuM3220 driving H-bridge N-mosfet

Hello DDer,

The ADuM3220 has two outputs that share a common ground on the secondary side. This means that unless there are very specific conditions, it is not best suited for driving a half-bridge configuration. The reason for this is that the high side channel must be able to follow the high-side FET up to the bridge voltage when the low-side switch is turned off.

Please look into the ADuM3223, ADuM4223, or the ADuM7223 for a half-bridge driver solution. These chips provide two separate grounds for the two separate output channels. One consideration that you must make is that the high-side channel has to be powered independently from the low-side channel. If your operating frequency and duty cycle are sufficient, a bootstrap configuration is usually the easiest and cheapest solution. The datasheets for these parts covers bootstrap operation.

Here is an application note about using the ADuM3220 to drive an H-bridge, but please note that the different channels of the two ADuM3220's are set to different sides of the H bridge. This allows their grounds to be at the same potential while they are driving their respective gates. It is suggested that you use a device designed to be used in a single leg of a half-bridge.

http://www.analog.com/static/imported-files/tech_articles/Inside_iCoupler_Technology_Driving_an_H_Bridge.pdf

If you are in a rush, and cost isn't your concern, since you probably have many ADuM3220's on hand, you could also dedicate an entire IC to the high-side, and another to the low-side. Just remember to power the high-side with some sort of floating supply, like a bootstrap or another isolated supply.

Let me know if you have any more questions,

RSchnell