66.9.4.4 Gain and Offset Errors

For:

• a given gain error: E_G (%)
• a given ideal code (C_i)
• a given offset error: E_O (LSB of 12 bits)

  in 12-bit mode, the actual code (C_A) is calculated using the following formula

  $C_A=\left(1+\frac{E_G}{100}\right)\times \left(C_i-2047\right)+2047+E_O$

Differential Mode

In Differential mode, the offset is defined when the differential input voltage is zero.

where:

• Full-scale error E_FS = (E_FS+) - (E_FS-), unit is LSB code
• Offset error E_O is the offset error measured for V_IN = 0V
• Gain error E_G = 100 × E_FS / 4096, unit in %

Single-ended Mode

The figure below illustrates the ADC output code relative to an input voltage V_IN between 0V (Ground) and V_ADVREF. The ADC is configured in Single-ended mode by connecting internally the negative differential input to V_ADVREF / 2. As the ADC continues to work internally in Differential mode, the offset is measured at V_ADVREF / 2. The offset at V_INP = 0 can be computed using the transfer function and the corresponding E_G and E_O.

where:

• Full-scale error E_FS = (E_FS+) - (E_FS-), unit is LSB² code
• Offset error E_O is the offset error measured for V_INP = 0V
• Gain error E_G = 100 x E_FS / 2048, unit in %