Offset error is the deviation from the ideal output voltage with zero input current through the device. Offset error can be referred to the output as a voltage error V_OE or referred to the input as a current offset error I_OS. Offset error is a single error source, however, and must only be included once in error calculations.

The output voltage offset error of the TMCS1100 is the error in the zero current output voltage from the VREF pin voltage as in Equation 3.

Equation 3.

where

• V_OUT,0A is the device output voltage with zero input current.

The offset error includes the magnetic offset of the Hall sensor and any offset voltage errors of the signal chain.

The input referred (RTI) offset error is the output voltage offset error divided by the sensitivity of the device, shown in Equation 4. Refer the offset error to the input of the device to allow for easier total error calculations and direct comparison to input current levels. No matter how the calculations are done, the error sources quantified by V_OE and I_OS are the same, and should only be included once for error calculations.

Equation 4.

Offset error drift is the change in the input-referred offset error per degree Celsius change in ambient temperature. This parameter is reported in µA/°C. To convert offset drift to an absolute offset for a given change in temperature, multiply the drift by the change in temperature and convert to percentage, as in Equation 5.

Equation 5.

where

• I_OS,drift is the specified input-referred device offset drift.
• ΔT is the temperature range from 25°C.