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LM70880-Q1: Output current issue

Manuel Perea
Prodigy 10 points
Part Number: LM70880-Q1

Tool/software:

Hi,

I have created a custom PCB and used the LM70880-Q1 to achieve an output of 15V and 6A from a 24V power supply. I would like to bring to your attention some issues I have encountered with this component.

Firstly, when powering the PCB, the desired output voltage is achieved, but the current is almost zero. Conducting some tests, when the LM70880-Q1 is heated to a low temperature with an air gun, the current increases to 4/5A. However, when the component is cooled, the current returns to almost zero. The reason for this is unclear. Do you have any thoughts on this matter?

Another issue that has come to light is that this component is being used in different zones on the PCB. As previously mentioned, I am experiencing an issue in certain zones. However, in some cases, only one or two zones are functioning correctly. I have attempted to solder this component in a number of different ways, including hand soldering, using an air gun or an oven

I would be very grateful for your assistance. Thank you in advance.

  • 0
    TI__Guru 56345 points

    Hi,

    Manuel Perea said:
    Firstly, when powering the PCB, the desired output voltage is achieved, but the current is almost zero. Conducting some tests, when the LM70880-Q1 is heated to a low temperature with an air gun, the current increases to 4/5A. However, when the component is cooled, the current returns to almost zero. The reason for this is unclear. Do you have any thoughts on this matter?

    What is the load being placed on the IC? When you say the current increases 4/5A, is this current referring to the current from the power supply? Have you tried reflowing the IC onto the PCB? We have not experience this phenomenon before with our evaluation board (EVM).

    Manuel Perea said:
    Another issue that has come to light is that this component is being used in different zones on the PCB. As previously mentioned, I am experiencing an issue in certain zones. However, in some cases, only one or two zones are functioning correctly. I have attempted to solder this component in a number of different ways, including hand soldering, using an air gun or an oven

    So, in some cases, the IC is performing as expected on different locations of the PCB but in other designated areas it is not? Sounds like a soldering issues to me.

    Ben 

  • 0 in reply to Ben C
    Prodigy 10 points

    Hi Ben,

    The load is a Peltier module that requires 4 A. The current I am referring to is the output current of the LM70880-Q1, as it must activate the load, but only when the LM70880-Q1 is heated. Once the LM70880-Q1 has cooled, the output voltage and current start to fall until they reach almost zero amps and around 4 V.

    I agree with you, but despite trying different soldering methods, I haven't had any success. Could you provide me the reflow soldering profile so that I can try again?

    Thanks for your response.

  • 0 in reply to Ben C
    TI__Guru 56345 points

    Hi Manuel,

    Are there any updates?

    Ben