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UCC21520EVM-286: dual output for half bridge configuration

Adam Daluga
Expert 6385 points
Part Number: UCC21520EVM-286
Other Parts Discussed in Thread: UCC21520, UCC20225, UCC20520

Hello,

I am having trouble configuring the UCC21520EVM. I thought that I am able to feed the board with a single PWM input, and give the device a programmable dead time setting with the built in POT. The result I am hoping for is to get is a dual output for a half bridge configuration. Is this configuration possible, or do I have to feed two separate PWM inputs to get two drive outputs?

Thanks,

Adam

  • 0
    TI__Genius 10652 points

    Hi Adam,

    For the UCC21520 EVM, you must use 2 PWM inputs (Both INA/INB channels) to have 2 drive outputs. This is required in order to use the half-bridge configuration like you mentioned. It is not possible to use only 1 PWM input and have the chip drive both outputs, as this IC isn’t designed to do this.

    Section 8.4.2.2 in the UCC21520 datasheet shows how Dead-time control is implemented and sample waveforms.,
    http://www.ti.com/document-viewer/UCC21520-Q1/datasheet/dt-pin-left-open-or-connected-to-a-programming-resistor-between-dt-and-gnd-pins-sluscj97845#SLUSCJ97845

    Another option is to take a look at UCC20225, which only needs 1 PWM input to drive the h-bridge. http://www.ti.com/product/UCC20225
    However, this part does not feature reinforced isolation and you'll need to see if the specs will work in your application.


    I hope this helps & makes sense. If you have any further questions, please let me know.

    Best,

    Dimitri James

  • 0 in reply to dimitri james
    TI__Expert 3355 points

    Hi Adam,

    Dmitri is correct that UCC21520 is a split input gate driver. The DT pin allows configuration for minimum deadtime, and is usually configured to a smaller amount than the desired deadtime. The controller can then assert its own deadtime, in order to meet the requirements of the system.

    For a reinforced isolation gate driver with PWM input in wide-body 16-DW package, I recommend that our customer use UCC20520. This driver is pin-2-pin with UCC21520, and uses the same EVM, but has only a single PWM input which drives OUTA and OUTB in complementary mode, with deadtime decided by RDT. 

    If this answered your question, could you please press the green button? If not, feel free to ask more questions.

    Thanks and best regards,

    John