• State
  • Locked Locked
  • Replies 3 replies
  • Subscribers 63 subscribers
  • Views 518 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.

TPS61020 input current problem, ESD?

Jan Zastera
Intellectual 260 points
Other Parts Discussed in Thread: TPS61020, TPS61070, TPS61220, TPS61200, TPS61260

Dear all,

we have problem with TPS61020 chip. We made 150pcs products with this IC and about 30pcs have problem with powering after few months. In normal state, there is 3,15V output voltage and about 45mA of output power when active and 50uA when standby mode. On defective units is right voltage, but current about 50-150mA in standby mode and 150-250mA in active mode. When we change this IC, there are right currents, so it has to be TPS61020 problem. We are desperate.. All products have the same PCB, same values of components. Same reflow, etc. We thought it could be ESD problem. Any ideas? Thank you very very much! Jan Zastera

Schematic is here: http://www.janzaudio.com/upload/scheme.png

(FPC5 is an input/output connector of signal)

  • 0
    TI__Guru**** 150610 points

    Typically, when an IC is damaged it draws excessive current.  You can take a failing IC and put it on our EVM to test it in a known good environment.  If it still draws excessive current, then it is likely damaged.

    Your local TI or distributor FAE can help you look through your design for possible sources of damage.  But here are some of the more common ones:

    Instability.  You are using much less than the recommended amount of output capacitance.  As well, with the second inductor of 10uH, a second output filter is created which impacts the loop stability of the TPS61020.  We recommend to use the output cap configuration shown in the D/S (2.2uF + larger tantalum) and no second output filters.

    ESD.  Yes, if the user can touch any pin or the device itself, ESD can cause failures.

    PCB layout.  Boost converters are very sensitive to PCB layout.  You need to follow the recommended layout in the D/S, with special emphasis on the output cap configuration, placement, and routing.

    Finally, there are many other, newer ICs that are likely more optimal for your given power needs.  These include TPS61260, TPS61070, TPS61220, and TPS61200.  I encourage you to look at some of these newer devices to see if any would work for your specific application.

  • 0 in reply to Chris Glaser
    Intellectual 260 points

    Hello Chris,

    thank you very much for your response. I will contact local TI. I have some contacts.

    According to instability:

    We are using 22uF output tantalum capacitor with low ESR. Ceramic capacitor causes noise most probably becouse of driving OLED. You are right. It is our fault, that we did not add also ceramic capacitor in parallel. Could this caused self damage of TPS61020, please?

    According to ESD:

    How do you recommend to protect DC-DC converter input, please? I try to found some information on your pages, but did not find. In production, it is strictly protected against ESD.

    According to PCB layout:

    We strictly follow layout in D/S.

    Thank you very much once again, Chris.

  • 0 in reply to Jan Zastera
    TI__Guru**** 150610 points

    You can measure the ringing on the SW pin on your layout to see if the lack of a ceramic cap on the output or your layout are causing issues.  See this app note: http://www.ti.com/lit/an/slva255/slva255.pdf

    TI makes ESD protection devices.  But also, keeping the pins out of contact by the user really helps mitigate any risk there.