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Original question:

UCC28780: TIDA-01622 schematic

UCC28780: tida-01622 board build issues

Chiachen Tsao
Prodigy 215 points
Part Number: UCC28780

Hi, are there complete set of pictures of the tida-01622? are there jumper wires in addition to one we found out we have to add but not documented..

We are seeing shutdown when drawing load beyond 3AMP, and not able to go beyond 28Watts. We have compared all the resistor values but are still having problems.

Help!

Thanks,

Chia

  • 0
    TI__Guru* 86286 points
    Hello Chia,

    I will contact the Tida design engineer and follow up with your question.

    Regards,

    Mike
  • 0 in reply to Mike O'
    TI__Guru* 86286 points

    Hello Chia,

    I contacted the designer of tida-01622 and he mentioned that were no jumpers and the released documentation was correct.

    So the next question is why you cannot get the required power out of the design.

    1. Are you using the same transformer?

    2. Did you use the same layout?

    3. Is there an incorrect component?

    4. Is your Opto coupler the same?

    At this point you could also trouble shoot the circuit as well. One of the following is most likely causing the UCC28780 to shut down.  Once you determine which you may be able to figure out what component is incorrect.

    1. Over voltage protection

    2. Over current protection

    3. VDD dropping out

    Lastly this could be due to the layout. You can use the tida-01622 as a guide of what the layout should like and compare it to the one you are using.

    Regards,

    Mike

  • 0 in reply to Mike O'
    Prodigy 215 points

    Hi Mike,

    RE: 1, 2, 3, 4 - the answers are all yes, we followed the BOM to the last details, we made sure the Opto is the same, same transformer. and yes, we have also fab TIDA-01622 PCB and assembled few to test, same identical problem.. so we are thinking there maybe component values that are off..

    Maybe we used previous release version of TIDA-01622? Attached is the .PDF of the main board of TIDA-01622 with the read line circling a jumper wire.

    So the problems we are seeing:

    1. With slight load, the voltage drops substantially, i.e. 5V would start around 5.04V and drops to 4.8 at around 1AMP. and at 4.5V around 3AMP load.. so around 4AMP load the circuit will reset.

    2. At 20Volt output, at around 1.4AMP draw, the circuit would reset. it is supposed to be setup to do 20V@3.2 AMP..

    So we have compared resistor and capacitor value, made sure the Opto is the exact part as spec'd on the BOM.. all the component are the same..  so we don't know how to move further.. any suggestions?

    Best,

    Chia

    TIDA-01622E1Mother board ed page 1.pdf

  • 0 in reply to Chiachen Tsao
    Prodigy 215 points
    Hi Mike, forgot to mention.. we spotted a mistake in TIDA-01622 BOM for main board.. R19 is listed twice, once for 511K 1% resistor and the second was 1M 1%, we assumed it was 511K..

    Best,

    Chia
  • 0 in reply to Chiachen Tsao
    TI__Intellectual 925 points
    Hi Tsao,

    Thanks for your interest in TIDA-01622.
    If you really copied the schematics and layout totally, I am sure there is anther jumper wire except the BUS+ you showed.
    However, please share with me your schematics and layout files, also BoM used in your design.
    It will be very helpful for me to make right understanding.

    1. About the output voltage issue, please check you use the same 431 reference device and the right bias current for 431. Because the Ic current is only uA rating, it will cause the 431 behavior abnormally if not use the same 431.
    2. About the reset issue, please measure the RUN signal to check which is the protection happening.

    Thanks very much!

    BR
    Cheng