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MSP430F6733: VDSYS and DVSYS, if not connected externally

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Replies: 2

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Part Number: MSP430F6733

Hello,
The DS p.14 says "(3) The pins VDSYS and DVSYS must be connected externally on board for proper device operation."

But a handy tester shows they are connected resistively. 1.5ohms on display.

Then can I ask the remaining risks if not connected?

  • Hello Hideaki,

    VDSYS: Digital power supply selected between DVCC, AUXVCC1, AUXVCC2
    DVSYS: Digital power supply for I/Os

    DVSYS is supplied by VDSYS so that the digital I/Os are always at the same voltage as the digital supply. Because of the auxiliary system, you will not want to connect DVCC to DVSYS as doing so could have the supply and I/Os at different voltages, most likely damaging the microcontroller. If not connected externally then the device core and the auxiliary voltage on the I/Os would be operating at different voltages, which is a critical violation of normal internal operating conditions. There should be no mass production of boards in this state as it is stated multiple times in the datasheet that VDSYS and DVSYS must be connected externally on board for proper device operation.

    Regards,
    Ryan

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  • In reply to Ryan Brown1:

    Hi Hideaki-san,

    from Quality point of view I only can recommend to follow the recommendation in the specification and connect VDSYS and DVSYS externally. Internally they are connected as described. The resistance you measure results most probably for bus resistance because the pins are on the oppsite corners of the die. Therefore reducing this by connecting it externally improve the system performance.
    So please follow the recommendations and connect it.

    Best regards,
    Dietmar Walther

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