SPI NOR flash runs at 1.8 V, but today’s advanced SoCs on sub-10-nm nodes operate at 1.2 V, hence the need for a 1.2-V I/O interface.
Advanced SoCs operate at voltages from 1.2 V or even lower. Supporting higher-voltage I/O structure like 1.8 V, which is used with many NOR flash devices, can increase the SoC die size and make it more expensive. Using a NOR flash device with a 1.2-V voltage input/output (VIO) feature helps reduce cost as well as power consumption.
