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Current measurement between DM3730 and TPS65950 at inductor

Luis Maeda
Prodigy 50 points
Other Parts Discussed in Thread: TPS65950, DM3730

Hi,

I am looking to measure the current consumed by the CPU/MPU of the DM3730, which is supplied by the TPS65950, I am using the Beagleboard-xM (I know there are current measurement pins on the board but they measure the current of the whole board).

Looking at the datasheets/reference manuals:

http://www.ti.com/lit/ug/sprugn4r/sprugn4r.pdf

http://www.ti.com/lit/ds/symlink/tps65950.pdf

Seeing that VDD1 is the power input for the MPU, the current needs to be measured at this point. In my board it is connected to VDD1 of the TPS65950. Based on the Figure 4-1 of the TPS65950, VDD1.L seems to be the output current whereas VDD1.OUT seems to be some sort of input to the TPS65950. The inductor LVDD1 (of 1uH) needs to be connected between VDD1.L and VDD1.

My question is, based on Figure 4-1 where there are arrows coming in and out of VDD1; is VDD1.L supplying the current? (there is an arrow pointing outside of TPS65950) In that case, if I put a probe on LVDD1 can I measure the current being consumed on VDD1?

Regards,

Luis

  • 0
    TI__Guru 65405 points

    Hi Luis,

    I think it should be difficult to measure current consumption by DM3730 CPU of the BeagleBoard-xM. I recommend you to use DM3730EVM board for CPU current measurement because it is more suitable for hardware developing and analyzing because the board has many points suitable for connecting measurement tools.

    BR

    Tsvetolin Shulev

  • 0 in reply to Cvetolin Shulev-XID
    Prodigy 50 points

    Hi Tsvetolin,

    Thanks for the info, I will try to get my hands on a DM3730EVM.

    In any case, I would like to know if the flow of current is as explained on the figure (Figure 4-1 of the TPS65950 Data Manual), in which the current goes out through VDD1.L and not VDD1.OUT (I imagine VDD1.OUT is for feedback). Also, seeing the schematics of the BBxM VDD1.L0 comes from pin C14, D15 and D16, I suppose from three pins to be able to supply enough current to the MPU. The same thing seeing the schematics of the DM37xEVM, in which VDD1.SW1, VDD1.SW2, VDD1.SW3 seem to be the output currents and VDD1.FB some sort of feedback. Is that the case? Therefore by measuring the current through the inductor LVDD1 (on TPS65950 Data Manual) it would be possible to measure the current of the MPU?

    Regards,

    Luis

  • 0 in reply to Luis Maeda
    TI__Guru 65405 points

    Luis,

    I recommend you the DM37xEVM board because it is easier to reach the pins but you could use the beagleboard-xM if it is not difficult for you.

    BR

    Tsvetolin Shulev