ADuM4223

Hi all,

I'm currently trying to designo full bridge converter using AD4223 as isolated gate driver. I just find some explications in the link below.

https://ez.analog.com/message/165762#165762

But i can't find a way to use this driver for synchronous rectification.. So i have here tow questions:

1- is it possible to drive the two Syncronous rectifiers using an ADuM4223?

2- if it's not , can you please suggest to me an other way to drive SR mosfets!

Thank you

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  • 0
    •  Analog Employees 
    on Mar 22, 2018 2:47 AM

    Hello,

    1. A non-isolated supply can be used as long as the ground of the non-isolated supply is at the same potential of the source/emitter of the power device you are driving. This is particularly important if you are wanting to drive a half-bridge. The high side switch will have its source/emitter follow the half--bridge voltage, which means you can't use a non-isolated power supply. In a bootstrap configuration, you are essentially using a capacitor to act as a floating voltage source for a little while, thereby creating a floating power supply.

    If you are driving only lowside devices, you could use a non-isolated supply to power the output regions (VDDA/GNDA and VDDB/GNDB).

    If you do have a topology that allows for a non-isolated power supply, this suggests that the VDD1/GND1 will share a common ground with the VDDx/GNDx supply. This is not a problem, but you will not have isolation between these regions. It is not uncommon to have GNDB and GND1 share ground, and have VDDA/GNDA fed by a bootstrap. This would be an example of a functional isolation topology, allowing the VDDA/GNDA region to serve as a high-side half-bridge gate driver.

    2. The ADuM4223 is similar to the ADuM7223. Functionally, they are very similar, but the differences come about in the packaging and isolation certifications. The smaller packaging of the ADuM7223 means the package can take less internal power dissipation than the ADuM4223. Additionally, because the ADuM4223 has much larger package creepage than the ADuM7223, it can withstand higher isolation voltages between the output regions. The parts can be interchanged in most designs, as the propagation delay and drive strengths are very similar.

    RSchnell

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  • 0
    •  Analog Employees 
    on Mar 22, 2018 2:47 AM

    Hello,

    1. A non-isolated supply can be used as long as the ground of the non-isolated supply is at the same potential of the source/emitter of the power device you are driving. This is particularly important if you are wanting to drive a half-bridge. The high side switch will have its source/emitter follow the half--bridge voltage, which means you can't use a non-isolated power supply. In a bootstrap configuration, you are essentially using a capacitor to act as a floating voltage source for a little while, thereby creating a floating power supply.

    If you are driving only lowside devices, you could use a non-isolated supply to power the output regions (VDDA/GNDA and VDDB/GNDB).

    If you do have a topology that allows for a non-isolated power supply, this suggests that the VDD1/GND1 will share a common ground with the VDDx/GNDx supply. This is not a problem, but you will not have isolation between these regions. It is not uncommon to have GNDB and GND1 share ground, and have VDDA/GNDA fed by a bootstrap. This would be an example of a functional isolation topology, allowing the VDDA/GNDA region to serve as a high-side half-bridge gate driver.

    2. The ADuM4223 is similar to the ADuM7223. Functionally, they are very similar, but the differences come about in the packaging and isolation certifications. The smaller packaging of the ADuM7223 means the package can take less internal power dissipation than the ADuM4223. Additionally, because the ADuM4223 has much larger package creepage than the ADuM7223, it can withstand higher isolation voltages between the output regions. The parts can be interchanged in most designs, as the propagation delay and drive strengths are very similar.

    RSchnell

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