For 16-bit conversions, the code transitions only after the full code width is present, sothe quantization error is -1 LSB to 0 LSB and the code width of each step is 1 LSB.23.7.2.5 Linearity errorsThe ADC may also exhibit non-linearity of several forms. Every effort has been made toreduce these errors, but the system designers must be aware of these errors because theyaffect overall accuracy:• Zero-scale error (EZS), sometimes called offset: This error is defined as the differencebetween the actual code width of the first conversion and the ideal code width. Thisis 1/2 LSB in 8-bit, 10-bit, or 12-bit modes and 1 LSB in 16-bit mode. If the firstconversion is 0x001, the difference between the actual 0x001 code width and its ideal(1 LSB) is used.• Full-scale error (EFS): This error is defined as the difference between the actual codewidth of the last conversion and the ideal code width. This is 1.5 LSB in 8-bit, 10-bit,or 12-bit modes and 1 LSB in 16-bit mode. If the last conversion is 0x3FE, thedifference between the actual 0x3FE code width and its ideal (1 LSB) is used.• Differential non-linearity (DNL): This error is defined as the worst-case differencebetween the actual code width and the ideal code width for all conversions.• Integral non-linearity (INL): This error is defined as the highest-value or absolutevalue that the running sum of DNL achieves. More simply, this is the worst-casedifference of the actual transition voltage to a given code and its corresponding idealtransition voltage, for all codes.• Total unadjusted error (TUE): This error is defined as the difference between theactual transfer function and the ideal straight-line transfer function and includes allforms of error.23.7.2.6 Code jitter, non-monotonicity, and missing codesAnalog-to-digital converters are susceptible to three special forms of error:• Code jitter: Code jitter occurs when a given input voltage converts to one of the twovalues when sampled repeatedly. Ideally, when the input voltage is infinitesimallysmaller than the transition voltage, the converter yields the lower code, and vice-versa. However, even small amounts of system noise can cause the converter to beindeterminate, between two codes, for a range of input voltages around the transitionvoltage.Application informationKL27 Sub-Family Reference Manual , Rev. 5, 01/2016388 Freescale Semiconductor, Inc.
