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Converting PPM (Parts Per Million) to Number of Bits (LSBs) for INL Specifications

Updated Sep 11, 2025

I looked at the specifications for my board online to find out what the INL was. I was expecting to see a value given in LSBs (least significant bits) but I see that the INL is given in PPM (parts per million). How can I convert this PPM value to LSBs?

Converting PPM to LSBs

To convert from PPM (parts per million) to LSBs (Least Significant Bits), please divide 1,000,000 by the number of LSBs.

Example:
For a 16-bit device with a specification of 10 ppm INL:

1,000,000/(216)=15.3 ppm/LSB1,000,000 / (2^{16}) = 15.3 \, \text{ppm/LSB}1,000,000/(216)=15.3ppm/LSB 10/15.3=0.65410 / 15.3 = 0.65410/15.3=0.654

The INL for this board is 0.654 LSBs.


Converting PPM to Voltage

To go directly from PPM to voltage, multiply the PPM value by the reference voltage.

Example:
For 10 ppm of 1 V:

10 ppm×1 V=10 μV10 \, \text{ppm} \times 1 \, \text{V} = 10 \, \mu V10ppm×1V=10μV

This represents 10 µV of Integrated Nonlinearity (INL).

Additional Information

  • INL stands for Integrated Nonlinearity, which is an accuracy specification for ADCs (Analog-to-Digital Converters).