Abstract: An integrated circuit having an analog-to-digital converter includes built-in self-test (BIST) circuitry. The BIST circuitry checks for monotonicity, and typically also that all possible codes are present, by applying a ramp voltage to the A/D input, while a state machine monitors the output. The state machine can check to ensure that the output increases by only one least significant bit (LSB) each time the output changes. A counter may be checked at the end of the test, to ensure that all the possible codes are obtained. The BIST circuitry may be activated, and the results monitored, through package terminals after the chip is packaged, thereby allowing for boundary scan testing. The inventive technique may be used to save testing costs during manufacture. In addition, system diagnostics in the field can become more cost effective.