The RX21A group is the product that 24-bit Delta-sigma ADC is built in for measuring instruments such as a smart meter. PGA (Programmable Gain Amp) is built in Delta-sigma ADC, which is possible to amplify analog signal at most 64 times. The RX21A group has peripheral functions with special features, such as RTC which enables Time capture on event-signal input through external pins and DEU (Data Encryption Unit) which enables to use Encryption/decryption functions of the AES standard.