ADUM4121-ARIZ

Hi,

I'm not able to understand how to use Vi+ and Vi- pins of the driver.

GaN Systems has a half bridge eval board based on ADUM4121A. They have following connections- 

Is it necessary to provide a complementary input to each driver? Can I just provide Vi+ signal and leave Vi- floating? i.e connect HS_PWM-> Vi+(HS Driver) , LS_PWM->Vi+(LS Driver)  and leave Vi- of both drivers NC



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[edited by: pranit at 6:16 AM (GMT -5) on 11 Dec 2020]
  • +1
    •  Analog Employees 
    on Dec 22, 2020 6:58 PM 2 months ago

    Hello,

    The VI+ and VI- pins on the ADuM4121 allow you to drive the inputs a few different ways.

    1) The first, and most intuitive is to drive each ADuM4121 with positive logic. To do this, connect each VI- to GND1. Then, with two different PWM signals, drive the two separate VI+ pins with complementary signals. This is the closest to what you described. You do need to ground the VI- pins though, and not leave them floating.

    In this mode, you could even use both VI- pins as disable pins (raise VI- pins to disable the outputs).

    2) The second method is to provide both VI+ and VI- pins with complementary logic. By having the VI+ of the lowside driver driven with the same signal as the VI- as the highside (and vice versa) you get one more layer of protection from shoot through. If the controller outputs high on both the HS_PWM and LS_PWM as the same time, a shoot through event won't occur on the outputs, as both outputs will go low. It is not necessary to operate the ADuM4121 in this mode, but it also doesn't hurt.

    RSchnell

  • Such a succinct and concise answer! Thanks RSchnell!