The on-chip oscillator achieves an accuracy of 1%. Existing RX600 and RX700 products could only achieve an accuracy of up to 2.5%. The RX660 can guarantee 1%, which reduces the customer's external oscillator and allows the customers to reduce costs. Most competing products have guaranteed 1% accuracy characteristics by design spec only, so when the MCU is mounted on the customer's board, the accuracy can be poor in some cases. In the case of the RX660, high accuracy is guaranteed even after the MCU is mounted.