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TMDX5535EZDSP: Power consumption in IDLE3

Andrey Kuznetcov
Prodigy 170 points

Part Number: TMDX5535EZDSP

I measured the current on CVDD (JP1) and IOVDD (JP4).

             OnStartup                   Idle3

CVDD     29.8 mA                   0.2 mA
IOVDD    20.1 mA                   20.0 mA

Are these measurements correct? 
Is it possible to reduce IOVDD consumption?

Hardware: TMDX5535EZDSP
Software:   CSL_PowerManagement_IDLE3_Example (csl_3.08)
  • 0
    TI__Mastermind 30110 points
    Hi Andrey,

    There are two components to IO power consumption: static and active power
    In IDLE3, all clock domains are disabled except for RTC, so I expect the active power component for all peripherals to drop to zero, leaving just the static power consumption (or leakage power).

    Are you probing DVDDIO current by measuring voltage drop acros the 1ohm resistor between JP4 pins 1 and 2? The onboard INA219 device can measure the current this way.

    Plug your use case into the power estimation spreadsheet to see expected IO power.
    - Power Estimation and Pwr Consumption Sum for TMS320C5504/05/14/15/32/33/34/35/45 (Rev. A)
    www.ti.com/.../sprabn0
    - The spreadsheet discussed in this document can be downloaded from the following URL: www.ti.com/.../sprabn0

    Can you verify you are actually in idle 3 mode when taking the power measurement? Are the peripherals idle or are their pins still toggling? Did you disable clocks to all perpherals with the clock gates (PGCGR registers)?

    Floating inputs can consume IO power. Do you have anything attached to the eZdsp, or is it in the out-of-box condition?

    One other consideration is the voltage of the DVDDIO rail. The static power and power variation between device is reduced with a lower DVDDIO voltage. In your custom design, consider DVDDIO = 1.8V.

    Hope this helps,
    Mark
  • 0 in reply to Mark M
    Prodigy 170 points

    Thanks for the detailed answer, Mark.

    I found out that consumption can be reduced by adding initial initialization of GPIO pins (mainly leds should be off) and configuring pullup resistors. I still have 6.5 mA consumption on DVDDIO but on my custom board after taking into account your advice I was able to achieve total consumption below 1 mW in idle3 mode. This is very close to spreadsheet power estimation (0,726 mW).
    Therefore, I believe that the same consumption should be achievable on EZDSP5535 board.

    Thanks for support!

  • 0 in reply to Andrey Kuznetcov
    TI__Mastermind 30110 points
    Andrey,

    Great! Thanks for sharing your solution.

    Its often better to sink the current from LEDs into a GPIO rather than to source the current to the LED from the GPIO.

    Regards,
    Mark