Should chopping always be used on the AD719x if minimum offset and offset drift is required?
With chopping disabled, the offset equals ±75 uV/Gain typical. With chopping enabled, the offset equals ±0.5 uV typical. Therefore, chopping gives an improvement in offset for gains of 1 to 64. The offset drift is better when chopping is enabled for gains of 1 to 16. The drift is ±100/Gain nV/°C typically when chopping is disabled compared with 5 nV/°C when chopping is enabled. For gains of 32 to 128, the ADC itself has very good offset drift. Therefore, chopping does not give any extra improvement in the offset drift. For gains of 32 to 128, the offset drift is 5 nV/°C when chopping is enabled or disabled.
Therefore, for gains of 1 to 16, chopping does optimize the offset and offset drift. For higher gains, the offset drift is the same irrespective of whether chopping is enabled or disabled. The offset error itself is higher. However, rather than use chopping, an offset calibration could be used to minimize this error.
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