Knowledge Base Article
Answer: The internal reference of PSoC 3 or PSoC 5 accurate to 0.1% across the process and full operating voltage. It has temperature coefficient of about 20 PPM/°C. The reference noise is 10 uV RMS. Using a low noise external reference will improve the effective resolution of the ADC. If the external reference has noise below 2 uV, the ENoB will improve by 1-2 bits.