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TPS61175: Chip keeps frying

Prodigy 190 points

Replies: 18

Views: 182

Part Number: TPS61175

Hi there,

I designed a simple boost converter board with this chip. My board boosts from 15V to 24V, the 24V is then used on optocouplers which are controlled by a beagle bone's inputs to switch the solenoid valves on and off. The board had been working fine for the past couple of weeks but all of a sudden stopped working. It could be a number of variables, one being that we switched from a benchtop power supply to a battery (this one to be exact: https://www.rrc-ps.com/fileadmin/Dokumente/Data-Sheets/DS_RRC2054.pdf ) . I was hoping to get someone that is an expert on this chip to look at my schematic and PCB layout to see if there are things that might be missing that could cause harm to the chip that I didn't think about. Thank you! 

   

  • Hi Brittany,

    It could be helpful to provide more details about the design requirements of the boost (min max input voltages, needed output current...).

    Please provide also L1 & D1 part numbers.

    I saw in your schematic that you chose C4 rated voltage to be 6.3V which is, for sure, not sufficient to handle 15V input voltage. A 50V capacitor will be Ok. You may need also to add additional input capacitance to handle the transients of the battery.

    Regards,

    Abdu

  • In reply to AIT GHRIB Abderrahman:

    Hi Abdu, thank you for your quick reply. Of course! we are using a battery which I don't actually know the min and max as the datasheet doesn't state that ( I attached the link to the battery in the previous post), My guess is it ranges from 13-17V. The needed output current of the system was about .5A and I calculated all the passive components that the chip could provide up to 1.5A output. I'm not quite sure where you saw that C4 is rated for 6.3V it is actually 25V. the L1 is MSS1038-153MLC and the diode is MBRA340T3G. I am attaching a picture of my bom as well just incase for reference. Thank you for your help! 

  • In reply to brittany cohen1:

    Hi Brittany,

    I'm the AE of this part.

    When the input is power supply, it is 15V right? Before you switch to the battery,  please test the battery voltage to ensure the battery voltage is not to high or low.

    One question, how did you switch the power supply and the battery? online switch or disable the TPS61175 then enable it again?

    Best Regards,
    Helen

    Boost DC/DC Solution

  • In reply to Helen chen:

    Hi Helen!

    I was hoping to hear from you (I didn't know how to contact you without posting on the thread).

    When you say test the voltage of the battery, do you mean to make sure it doesn't exceed the 18V input? Why would the min be a concern, since there is no way the battery would go below 2.9V.

    Also, what do you mean by how did I switch the power supply? If you are asking how did I turn the power supply on and off we just used a standard SPST switch and attached that to a dc power jack.

    Last question: do you think the fact that I didn't include any flyback diodes around my MOSFET optocouplers would have caused the chip to fry? Thank you! 

  • In reply to brittany cohen1:

    Dear Sir,

    Yes, you need to check the battery voltage to ensure it is not too high or too low. If the battery voltage is too low, the input current(inductor current) will be very high, if the current rating of the inductor is not enough, it may saturate.

    I need to know the sequence of how you switch the power supply to battery: turn off the power supply, then add the battery voltage through a SPST right? Did you add any inductor or capacitor after the SPST? the high voltage spike during switch the SPST may also damage the IC.   Please draw a block diagram of the power supply, the location of the SPST, battery. and the on/off sequence of the power supply, battery, SPST.

    Also I need to know  the exact moment when the IC damaged? I guess it happened just at the time when the battery voltage added.  But need you confirm.

    Best Regards,
    Helen

    Boost DC/DC Solution

  • In reply to brittany cohen1:

    By the way, could you please tell me which pin of the TPS61175  damaged? Vin pin? Enable pin or the SW pin? you can test the impedance from the pin to the GND.

    Best Regards,
    Helen

    Boost DC/DC Solution

  • In reply to Helen chen:

    Hi Helen, Here is a picture of how the switch and the power from the battery are attached to the circuit. I didn't add anything besides what was needed to boost the tp261175. To answer your other question. that is hard for me to answer. as I just designed the board and then was told by a peer that the board stopped working. So I do not know the exact order of operation. I was told that they were running solenoid valves from the board for several hours then turned everything off, then they turned things back on and nothing was happening. 

  • In reply to Helen chen:

    What does testing the impedance of the pin show me? What should I be expecting to see by testing the impedance of a pin?

    When I looked at the SW pin it didn't seem to be behaving as expected 

  • In reply to brittany cohen1:

    Dear Sir,

    Please solder the IC off the pcb , then test the impedance between SW(+) and the GND(-), also the Vin(+) and GND, EN and GND. There's an anti parallel diode from the GND to each pin, so please during the test, GND should be at - to make the test accurate.

    Best Regards,
    Helen

    Boost DC/DC Solution

  • In reply to Helen chen:

    Hi Helen,

    Again, what should I expect to see once I am testing the impedance? (also I am a woman, haha)