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Compiler/UCC21520: UCC21520 gives -5,1 V on OUTA and OUTB pins

user5290031
Prodigy 10 points
Part Number: UCC21520

Tool/software: TI C/C++ Compiler

Hello

I have got problem with UCC21520 driver. On the out pins: OUTA and OUTB there is -5 V all the time. Driver is turning off transistors. The DISABLE pin is set low.

my circut:

parts parameters:

The PWM signal is from Arduino Uno, U=5 V, f  = 24 kHz. I have measured this signal on the primary pins of chip, it looks good.

What can be the problem? can you help me?

Parametr
Wartość
 
 
 
 

  • 0
    TI__Genius 13445 points

    Hi user,

    I will work with you to solve this issue. How are you implementing the 25V supply connected between VDDA and VSSA?

    Thanks.

    Regards,

    -Mamadou

  • 0 in reply to Mamadou Diallo
    TI__Genius 13445 points
    Hi User,

    Thanks for your patience.

    Can you please confirm the voltage across CA3 (as a sanity check)? Can you please probe VDDA and VSSA?

    Additionally, the switching current of VDDA is given by Qg * Fsw(24kHz). Can you please specify the MOSFET you're using in order to determine the gate charge? The reason I ask is to ensure this switching current added to the quiescent of the driver is within acceptable range of the current capability of the driver to bias the diode.

    Also, you probably already have this covered but it is important to ensure that the local bypass capacitors between VDD and VSSA pins are placed very close to the pins for proper operation of the driver.

    Thanks in advance for the additional details.

    Regards,

    -Mamadou
  • 0 in reply to Mamadou Diallo
    TI__Genius 13445 points
    Hi User,

    We have not heard from you in a while, I am going to close this thread and therefore assume that you've resolved the issue. If so, please share resolution for others on the forum to learn from.

    If you're still having issues, please let us know and and we'll gladly assist in finding a resolution to the problem.

    Thanks.

    Regards,

    -Mamadou