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MSP430F5510: Moisture and Internal LDO output voltage problem

dipesh karli43
Prodigy 140 points
Part Number: MSP430F5510
Other Parts Discussed in Thread: MSP430F5509

Hello All,

I am writing this problem regarding TI's MSP series microcontroller i.e. MSP430F5510.

A few months ago, we have purchased 125 nos. microcontroller from MOUSER. In that purchased lot, we have faced many problems in Microcontroller internal LDO output voltage, i.e. getting 2.5V regulated output instead of regulated 3.3V. We have raised a query regarding it in TI forum. In forum discussion, members tells that it may happen due to moisture and suggested 8-hour baking process for IC.

Now, we have purchased 250 nos. Microcontroller from MOUSER and we are facing similar kind of issue again. i.e. Internal LDO output voltage problem. We have requested MOUSER a return of the recently purchased lot but they are declining for that.

In this lot, we have noted that when we have opened the package for soldering IC, its moisture indicator indicate all BLUE mark there is no sign of any moisture. i.e. no any PINK circle on moisture indicator.

Here, I want to know is there any other issue which can affect microcontroller performance? I also point out that, Microcontroller MSP430F5510 is only available with MOUSER even TI does not have its stock. Is there any production level fault in this series microcontroller?

Can anyone suggest what can I do for this?

Regards,

dipesh

  • 0
    TI__Guru 56685 points
    Hello dipesh,

    I'm not aware of any issue with LDO output current for the USB module at this time, and no errata seem relevant to your issue.

    Can you explain how you are testing the LDO output voltage? Is this on a custom board or a TI target socket?

    If a custom board, what does your schematic look like from the MSP430 perspective? Can you share a schematic snippet of the MSP430 + its power rails + USB connection?

    Is the US LDO powering anything else in the system?
  • 0 in reply to Jace H
    Prodigy 140 points

    Hello JH,

    I am testing LDO output voltage using custom board.

    I have shared snapshot of schematic with this.

    No, LDO in system(schematic) does not power up any other device except itself.

    In recent times we have ordered samples of MSP430F5509/10 from TI. The sample ICs work perfectly on my custom board. ICs purchased from MOUSER having this kind of LDO output voltage issue. Is there any possibility that controllers may exposed to external environment at MOUSER storage facility and this issue kind of issue arises due to this?

  • 0 in reply to dipesh karli43
    TI__Guru 56685 points

    Hello Dipesh,

    "In recent times we have ordered samples of MSP430F5509/10 from TI. The sample ICs work perfectly on my custom board. ICs purchased from MOUSER having this kind of LDO output voltage issue. Is there any possibility that controllers may exposed to external environment at MOUSER storage facility and this issue kind of issue arises due to this? "

    To comment on above, you would have to speak with your distributor Mouser about this. That being said, I don't think it's your issue.

    Looking at your schematic snippet, I see a few issues that could be placing the MCU in a weird state.

    Some things I see:

    • No cap on VUSB. Needs to be 220nF like cap on V18. Please see USB-PWR section of MSP430F5510 datasheet for recommended values. Also see section 4.1 Ti Reference Design for USB Interface for recommended USB schematic ()
    • VCORE cap is wrong value. Please see Recommended Operating Conditions in the MSP430F5510 datasheet for official value. It should be 470nF.
    • Power Decoupling caps should be on each DVCC/AVCC line. Its recommended to use 0.1uF as close to these pins as possible, with a 10uF cap upstream, close to the power source to the MSP430 branch of the power. 
    • Its not shown on our snippet, but what does your RST line have on it? Does it have the recommended pullup resistor and cap to ground?

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