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ADS4245 channel standby and power down

Knut Olav Skyttemyr
Intellectual 290 points
Other Parts Discussed in Thread: ADS4245

Hi!
I have two questions regarding the ADS4245:

From table 7 in the datasheet, there is a chA standby chB active mode. What about chA active and chB standby, is this available?

I need to shut the ADC down when not in use to save power.  I have two options:
a) use the ctrl-pins to enter power down mode.
b) to disable the analog 1.8V power supply.

I cannot find any information in the datasheet regarding power sequencing and whether it is possible to shut down the analog power supply while the digital power (output buffer) supply is still enabled.

please advise!

thank you and best regards

Knut Olav Skyttemyr

  • 0
    TI__Genius 17320 points

    Hi Knut,

    Both channels can be put into standby using the SPI interface by writing a 1 to bit 7 (STBY) of register 0x45. I do not think both can be powered down using the CTRL pins. You can also use PDN GLOBAL which will power down the entire ADC including the internal references and output buffers. This is accessible through register 0x45 or the CTRL lines. Wakeup time from global power down is longer (100 us). I would think that this is a much better option than turning off the analog supply.

    In terms of power supply sequencing, take a look at the absolute maximum ratings table. The voltage between AVDD and DRVDD is specified as -2.4 V to 2.4 V. This indicates that AVDD could be powered down without damaging the part.

    Regards,
    Matt Guibord

  • 0 in reply to Matt Guibord
    Intellectual 290 points

    Thank you for the quick reply!


    So you cannot set chB to standby/power-down and chA to active with either the SPI or CTRL pins?

    Chapter 8.4.4.2 states that each ADC channel can be powered down.

    best regards

    Knut Olav

  • 0 in reply to Knut Olav Skyttemyr
    TI__Genius 17320 points

    Hi Knut,

    That's correct, section 8.4.4.2 is a bit misleading. You can powerdown both channels at once using the SPI interface, or powerdown just channel A using the CTRL pins.

    You can powerdown the output buffers individually using register 0x41.

    Regards,
    Matt Guibord