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ISO5852S: diode protection for DRAIN

[FAE] Andrew Wang
Genius 10685 points
Part Number: ISO5852S
Other Parts Discussed in Thread: UCC21732,

Hi Team,

In our UCC21732 EVM sch below, we placed a diode at DRAIN to COM.

Customer wants to know what is the purpose of this diode?

And Does ISO5852S need it?

Thanks!

Andrew

  • 0
    TI__Expert 4875 points

    Hi Andrew,

    The Schottky diode is another means of protecting the DESAT pin during the high voltage transients at the drain of the power switching device. Schottky diodes have very low reverse recovery and higher voltage capability as compared to the Zener diode. This is especially important for SiC MOSFETs, which switch at a very fast rate at high voltages. The Schottky diode is not a requirement, but may be beneficial in many systems. The ISO5852S if operating in a system with high frequency and high voltage switching on the DESAT pin may also benefit from the placement of the Schottky diode. However, it is not a requirement.  

    Regards,

    Audrey

  • 0 in reply to Audrey Dearien7
    TI__Expert 4875 points

    Hi Andrew,

    An update: the Schottky diode is beneficial to clamp COM to less than the forward voltage drop of the Schottky diode to ensure the pin remains within the voltage limits of GND2 – 0.3 to VCC2 + 0.3. 

    Regards,

    Audrey