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ADS1013: Max Pull up resister for ADS1013 I2C communication

Takashi Onawa
Genius 13200 points
Part Number: ADS1013
Other Parts Discussed in Thread: ADS1018

Hi Team,

I want to use the largest pull up resister(Like 100k ohm) for ADS1013 I2C communication  to reduce total current consumption of a system.
But Max tR is specified as 300ns at 7.6 Timing Requirements: I2C in the datasheet. Slower communication rate like 10kHz is acceptable for system requirement but it will be hard to keep the tR and tF requirement if i choose 100k ohm as pull up resister in the system.

Then I have following questions. 
1. Is it possible to use slower tR rate with low speed communication such as 10kHz clock rate?
    (In other word, can we use 100k ohm as pull up resister in the system using ADS1013?)

2. If the answer for question above is NO, Why the value is limited to 300ns?

Regards,

Takashi Onawa

  • 0
    TI__Guru* 98055 points
    Takashi-san,


    I'm not aware of why the rise time is limited to 300ns. However, this is also part of the standard I2C specification for I2C running in Fast Mode. It is also listed as 300ns.

    However, the specification for Standard Mode is 1000ns for rise time (but also 300ns for fall time). In the ADS1013 datasheet, there is no listing for the specifications for Standard Mode.

    If you need to limit the current used for communicating with the device, I would use an SPI interface instead. The ADS1018 is a similar device (but has two differential channels and a few extra features).


    Joseph Wu