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UCC27531: Output Signal Problem

Mert Kantarcioglu
Intellectual 390 points
Part Number: UCC27531
Other Parts Discussed in Thread: UCC28180, UCC28951, UCC28950,

Hi,

I have designed PFC stage according to TIDA-00779 using UCC27531D.

I am testing the circuit without AC Input. I have connected a DC source to Vsense to simulate HVDC Bus. While Vsense between 1.2V and 5.2V I can get the output signal from gate of PFC Controller (UCC28180) also I can see the sam signal at input of UCC27531D. But at the output of the UCC27531D I can see just only VDD signal. When I change Vsense to <1.2V and 5.2> output will be switched back to GND. When I isolate output signal from rest of the circuit result was not changed.

Question is why I could not see the same input signal at the output of the UCC27531D?

Please find schematics and waveforms below.

Beside that I have looking for a step by step debug process for UCC218180 like UCC28951, but I could not find. Do you have any resource to make circuit running step by step?

Input of UCC27531D:

Output of UCC27531D:

5516.0447.UCC28950, UCC28951 Debug.docx

PFC Devresi.pdf

  • 0
    TI__Genius 13445 points

    Hello Mert,

    Thanks for reaching out.

    It sounds like your inquiry consist of 2 issues.

    I can help address issues related to the UCC27531 device then get you in touch with the team supporting the UCC218180 device.

    In FIgure 1 above, it looks like high duty cycle signal driving the IC's IN pin signal does not seem to fall below Vin_L threshold to command a low state to the OUT pin. Seems like Vin,min = ~=6V? which for UCC27531, VIN should be close to Vin_L = 1V as specified in EC table section 5. This might explains why OUT is stuck high and does not follow IN signal.

    Regards,

    -Mamadou