ADC built-in self-test algorithms

AN4371

14/29

DocID025337 Rev 1

conversions are distant in term of time, there is a temporal non-correlation that makes the

result unreliable. With S algorithm S0 (step) is measured if the ADC internal bandgap

S1 measurement is delayed from the S0 measurement, then a reference voltage drop may

occur. Performing then S1 measurement, where are to be used S0 results, which was good

at the time when it were measured, but not correct for actual measurement. The problem

may be masked here. This is the reason why is ADC one-shot conversion mode not suitable

for algorithm S measurement.

In the ideal environment results must be same in both, one-shot and scan mode. Because

there is never any voltage drop in the ADC reference or supply due to ideal environment.

Figure 7. ADC self-test configuration – Algorithm S

On Figure 8 below is presented the basic self-test flow for algorithm S. The test channel is

started automatically after normal channel conversion as presented on Figure 9.