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ADS1015: ADS1015 and ADS1115 repalcement

Alan Chang
Intellectual 2310 points
Part Number: ADS1015
Other Parts Discussed in Thread: ADS1115

Hi ,

  I'm studying ADS1015 and ADS1115, and find the package is same, however, the bit resolution is different. If customer designs ADS1015, is it possible to use ADS1115 with same FW or calculation to get voltage?

The ADC is used to monitor different power rails. I'm not sure different LSB voltage level impact these 2 device voltage calculation or not. Thanks.

  • 0
    TI__Guru* 97435 points

    Alan,


    The ADC data conversion output for the ADS1015 and the ADS1115 are listed in the datasheets in the Data Format sections of the respective datasheets. For the ADS1015, this is in section 8.5.4 on page 22. For the ADS1115, this is in section 9.5.4 on page 26.

    The ADS1115 has a data format for 16-bit data. The ADS1015 has a format for 12-bit ADC data over 16 bits, where the lowest four LSB are 0s. However, the firmware could be with conversions based on LSb size. Using an example of the ±2.048V FSR.

    For example, the ADS1115 has a max reading from the conversion register of 7FFFh, and a min reading of 8000h. This converts to 32767d and -32768d. If you used the LSb size to convert these values, you could take the ADC conversion and multiply the number by the LSb size. The LSb size is 62.5uV. This way you get:

    Max = 32767 * 62.5uV = 2.047935V
    Min = -32768 * 62.5uV = -2.048V

    The ADS1015 has a max reading from the conversion register of 7FF0h, and a min reading of 8000h. These convert to digital as 32752d and -32768d. You could use the same LSB size, incorporating the four 0 LSbs as part of the data. You would get:

    Max = 32752 * 62.5uV = 2.047V
    Min = -32768 * 62.5uV = -2.048V

    This would give similar results for the ADC conversion data with the same firmware.

    I'd note that the devices are not exactly the same. The configuration register is setup the same way but the exact data rates are different.


    Joseph Wu