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AMIC120: Power supply

Eddie Esparza
Prodigy 170 points

Part Number: AMIC120

Hi team,

I have a customer who has a couple of questions regarding power on AMIC120:

  1. If they're not using DDR, do they still need the 1.2V power supply?
  2. Do we have an estimation of power consumption of the PRUs? i.e. how much power is saved by not making use of the PRU-ICSS

Thanks,
Eddie

  • 0
    TI__Guru* 85185 points
    Hi Eddie
    I will forward #1 to our DDR expert.
    On #2 , I believe the power savings between fully utilizing the PRU vs not using it at all will be somewhere in the order of 30-50 mW, if the customer is just trying to power down /clock disable PRU because they don't use PRU in their application the power savings will be even lower .
    IMHO it is not worth dabbling with shutting it down etc.

    Regards
    Mukul
  • 0 in reply to Mukul Bhatnagar
    TI__Guru* 91370 points
    Eddie,
    for DDR, the proper method of handling the unused pins is to tie off the DDR_DQSn[x] pins to the VDDS_DDR supply via a 1-kΩ resistor and pulling the DDR_DQS[x] pins to ground via a 1k-Ω resistor. This must be done for each byte not used. Also, include the 49.9-Ω pulldown for DDR_VTP.

    The VDDS_DDR and DDR_VREF power supply terminals need to be connected to their respective power. Even though VDDS_DDR is typically 1.2V for LPDDR2 or 1.35V for DDR3, they can connect this to 1.8V (more commonly available because of other 1.8V IOs) instead of having to provide another voltage rail for an unused interface. DDR_VREF should be 0.9V (they can just use a simple resistor divider for this)

    All other DDR interface pins can be left unconnected (no traces should be connected to these pins)

    Regards,
    James
  • 0 in reply to JJD
    TI__Prodigy 170 points

    Thanks James. One follow up question from the customer: What is the current consumption of VDDS_DDR when it is connected to rail of 1.8V?

    Thanks,
    Eddie

  • 0 in reply to Eddie Esparza
    TI__Guru* 91370 points
    Eddie, i don't have any specific measurements. If they tie off the interface as previously explained, it should be negligible.

    Regards,
    James