DocID025337 Rev 1

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AN4371

ADC built-in self-test

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ADC built-in self-test

For safety relevant applications, it is important to perform the ADC functionality check at

incorporated inside the ADC. Tests at application level can be used in place of the ADC self-

test to verify the integrity of the ADC itself. It is a user's tasks to choose the counter-

measure which better fit his needs.

Three types of Self Testing algorithms have been implemented inside ADC analog.

•

Supply Self test: Algorithm S

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Resistive-Capacitive Self test: Algorithm RC

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Capacitive Self test: Algorithm C

The built-in self-tests use analog watchdogs to verify the result of self-test conversions.

During the production factory testing, accurate threshold values for these watchdogs are

stored in the Test sector of the flash memory. Each testing algorithm contains its own

threshold values. Each microcontroller has its own threshold values. Most values are

identical or very similar across the microcontrollers. The build-in self-tests can be executed

1.1

ADC Built-in self-test description

The ADC implements a channel (self-test channel) dedicated for self-testing. The self-test

schedule is done via special set of self-test registers in ADC. ADC also offers capability of

monitoring the converted data using analog watchdog registers and flags the error to the

Fault Collection and Control Unit (FCCU) in case any of the algorithms fails.

a.

depending on the specific safety concept, the ADC self-test can be run only once after the boot

b.

this AN focuses on ADC working in CPU mode