ADUM4221 DT pin connect to 5V(VDDI)


           Customer use SI8233 on board. We will use ADUM4221 to replace it. Customer don't use DT function of SI8233 and DT pin connect to 5V(VDDI).

           Could ADUM4221/ADUM4221-1 DT pin connect to pull hign (5V) for direct replacement? Or ADUM4221-2 show NC pin but that datasheet show( No Connect. Do not connect to these pins). Does ADUM4221-2 also connect to  pull hign (5V) directly? Or we do not connect to any circuit on DT pin for ADUM4221-2. Thank you. 



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  • +1
    •  Analog Employees 
    on May 9, 2021 6:20 PM in reply to

    Hello Patrick,

    It is correct that the ADuM4221-2 does not contain overlap protection. The ADuM4221-2 will allow both channels to be on at the same time if the inputs are both high.

    Overlap protection and deadtime control are very related. In an ideal overlap protection only scheme, the deadtime would essentially be 0 s. Deadtime control also does not allow overlap between the outputs, but spaces the timing between the outputs by a minimum timing.

    What does "disable the DT pin" mean? The lowest deadtime we can achieve  with the ADuM4221 is with a 10 kΩ resistor, resulting in around 62 ns. The ADuM4221 provides both deadtime control and overlap protection. If the customer needs low deadtime, but also overlap protection, this is the configuration they should use.

    If the customer is looking for less than 62 ns deadtime, using the ADuM4221-2 with complementary inputs on the VIA and VIB pins with proper deadtime between them can achieve this. The ADuM4221-2 does not have overlap protection, so if there is an input signal where both VIA and VIB are high, both outputs VOA and VOB will go high. This is not the exact same action as the SI8233 with the DT pin held to VDD1.

    1) Is there deadtime provided by the controller square waves?

         If no deadtime is being provided, or the deadtime is not guaranteed to be trusted, I would recommend the ADuM4221.

    2) Does the customer need overlap protection?

         The ADuM4221 is the best fit, but will come with a minimum deadtime.

    3) What deadtime is needed in the system?

         If a deadtime over 62 ns is needed, setting the DT pin on the ADuM4221 to 10 kΩ is the best solution.


  • Hello RSchnell

            Customer use SI8233 and DT pin pull high and looks default dead time 400ps. So we can use ADUM4221 that put 10K resistor to GND for 62ns lowest dead time. Correct? Thanks.