• State Resolved
  • Locked Locked
  • Replies 6 replies
  • Subscribers 64 subscribers
  • Views 144 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TPS61288: Thermal Performance

Dharun Sangrithiyayan S
Prodigy 40 points
Part Number: TPS61288

Tool/software:

Dear Team,

We have designed a 18V @5A output from a 12V input using TPS61288.

While checking we found out that at around 3.5A the IC is getting heated up and output drops to 11V.

I hope this is happening because of thermal shutdown, but when we use a fan the IC is working fine upto 4.5A.

Our PCB is 2 layers and for circuit we followed webench.

Is there any other way to reduce heat in the IC or if there is anything we missed in our design, which leads to more heat dissipation?

Regards,

Dharun S

  • 0
    TI__Genius 17250 points

    Hi Dharun,

    Nathan is out of office this week, reply may delay to next week. Thanks for your patience.

  • 0 in reply to Shipeng Cheng
    Prodigy 40 points

    Hi Shipeng,

    Thanks for the update.

  • +1
    TI__Genius 12335 points

    Hi Dharun,

    Sorry for the delay response.

    The thermal performance is related to efficiency and PCB layout, there are some general ways you try with to improve the thermal performance,

    1.Use inductor with larger inductance or smaller DCR so that the inductor loss could be lower, can be helpful with the efficiency improvement.

    Also sometimes if the thermal of inductor is very poor, it could also cause negative impacts on the heat of our IC.

    You can check the inductor and the IC, which temperature is higher. If it is inductor, then using a better inductor would have more improvement on heat.

    2.Improve layout by using thicker copper per layer, for example 2oz copper, and also increasing the copper area of power trace like VIN VOUT, and adding more vias on these power trace could be also helpful with the thermal results.

    3.Avoid placing the different heat devices together on the board if not necessary to make the heat distribution is more uniform on the board.

    Let me know if you have further questions.

    Regards,

    Nathan

  • 0 in reply to Nathan Ding
    Prodigy 40 points

    Hi Nathan ,

    Thanks for the response.

    We have placed the IC on the bottom side and only IC is there ,I will check if the inductor/ IC which is getting heated up. I have used the webench recommended inductor part.

    Also, about that 11V is it because the thermal protection ? Because we have to use it for a 3.5A load and we are planning to use a heat sink.

    Regards,

    Dharun S

  • +1 in reply to Dharun Sangrithiyayan S
    TI__Genius 12335 points

    Hi Dharun,

    If the output is keeping at 11V, I don't think it is caused by thermal protection, because the device will stop switching after thermal protection. 

    If the output voltage keeps at a voltage that is lower than target voltage (11V <  18V), it is more like to trigger peak current limit, if peak current limit is triggered the switching current is limited at ILIM, so the output power is limited.

    But considering the 15A current limit of TPS61288, it seems like impossible to trigger peak current limit at the condition Vin=12V, and Vout=18V/3.5A (if the peak current limit is triggered, the COMP pin voltage is clamped at 1.88V(typ.), you can also check this to know if the peak current limit triggered).

    In EVM the TPS61288 can support 12V to 18V/5A without problem at room temperature.

    I am thinking if there is a long wire at input or output there then causing a line loss so you find the output voltage drops.

    If your confirm you setup is ok, maybe you can share the some waveforms like VIN, VOUT, SW, COMP or anything more so that we can know what cause the voltage dropping. Thanks.

    Regards,

    Nathan

  • 0 in reply to Nathan Ding
    Prodigy 40 points

    Dear Nathan,

    Thanks for the response .

    I will check for the comp pin voltage. As we are in the testing phase we are using a electronic load .We took the load up to 4.5A and with the help of a cooling unit/fan the output is holding 18V . 

    We will try to get the waveforms  and share