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Original question:

UCC27519: UCC27519 max allowed power dissipation

UCC27519: No output when Vdd is 5.5V and In+ is 3V square wave

PYTsai
Genius 10355 points
Part Number: UCC27519
Other Parts Discussed in Thread: UCC27517, UCC27511A

Hi 

Can you help, we are using UCC27519, when VDD = 5V and IN+ is 3V square wave the device work correctly. 

However when increase the VDD to 5.5V, In+ the same is 3V, there is no output, does this match the spec? thanks!

  • 0
    TI__Genius 13445 points

    Hello, 

    Thanks for your help promoting our drivers, my name is Mamadou Diallo, from the High Power Drivers team.

    UCC25719 uses a CMOS type input structure meaning that the driver's threshold voltage is proportional to VDD. To turn on the device, input signal must exceed the 55% of VDD and to turn off the device, the input signal must be below 39%VDD. 

    So in your case, using VDD=5.5V, the threshold of the driver will be 3.025V. That is likely the reason for the output staying please confirm by increasing VIN+ to 3.3V. Section 9.3.3 discusses this.

    If your application requires a constant or fixed PWM signal, please consider using a TTL type input threshold. We have wide portfolio of driver can could achieve this including UCC27517 and UCC27511A.

    Please let us know if you have further questions or press the green button if this addressed your inquiry.

    Thanks.

    Regards,

    -Mamadou