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ADS1258-EP: Partial Power Down Feature?

Eren Erdogan
Intellectual 280 points
Part Number: ADS1258-EP
Other Parts Discussed in Thread: ADS1258, ADS1282

 Hello TI,

Is there partial power down feature of ADS1258-EP?

If possible, I plan to use such way that DVDD (3.3V) will be always active, AVDD (5V) will turn on and off from time to time.

 

Regards,

Eren

  • 0
    TI__Mastermind 35141 points

    Hi Eren,

    See the verbiage from the ADS1258 datasheet below about Idle Modes and Powerdown mode. Powerdown mode does not seem like what you want, but one of the Idle modes may be acceptable for what you are trying to accomplish.

    I am not sure what you want to achieve by powering down AVDD but leaving DVDD enabled all the time, so I defer to you as to whether one of the Idle Modes will work for your application.

    There are no other ADS1258 modes that offer powerdown features.

    -Bryan

  • 0 in reply to Bryan Lizon86
    Intellectual 280 points

    Hi Bryan,

    Thanks for your answer. Firstly, before i asked the question, i had reviewed the datasheet in detail. Idle mode or power down mode isn't suitable for me. Avdd/Avss/Dvdd are all active in these modes. I didn’t mean these.

    I want to ask if it is acceptable to power off the analog supplies (AVDD and AVSS), but keep the digital supply (DVDD) active? Is it okay to partially power down the ADC (AVDD/AVSS off, DVDD on)? In this state, any analog input won’t be driven, clock input will be disabled and all digital pins are held low.

    Datasheet states that “The analog and digital supplies should be applied before any analog or digital input is driven. The power supplies may be sequenced in any order.” We obey this rule in power-up sequence. However there is no information in the datasheet about power-down sequence and partial power-down. Therefore i can’t be sure, i wonder if it's acceptable.

    I’m planning to use the ADC in a system where there are two different voltage levels. System power (3.3V) should always be on, but sensor power (5V) should be on and off from time to time. If i can partially power down the ADC, i will be able to simplify my design. I won’t need extra electronic components. Therefore it is important for me to know whether the ADC will work in this way.

    A similar question was asked for ADS1282 too. (https://e2e.ti.com/support/data-converters-group/data-converters/f/data-converters-forum/756863/ads1282-is-it-okay-to-partially-power-down-the-adc-avdd-avss-off-dvdd-on) It is stated that it is possible. Hopefully it's also possible for ADS1258-EP.

    Regards,

    Eren

  • +1 in reply to Eren Erdogan
    TI__Mastermind 35141 points

    Hi Eren,

    Yes you can power down just the analog, though keep in mind the recommendations in the e2e thread that you referenced in your last post. Specifically, making sure that none of the analog inputs still have voltages applied, or you might damage the ADC.

    Also, Chris makes a good point about the supply decoupling capacitors discharging slowly, causing the ADC to potentially get into weird modes. So just keep this in mind as you develop your system.

    Ultimately, it is possible, you just need to take a few precautions to ensure proper operation during power-down/power-up cycles

    -Bryan