Hello zeng,

See below, please!

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>>问题1:如果将NVCC_3V3改成NVCC_1V8后，boot 配置电路 和BT_CFG  IO端口 上拉电阻的电源 NVCC_SNVS、VNCC_JTAG_3V3、VNCC_SAI1_3V3是否需要做相应的调整，以保证IO口的电平保持一致。(1)boot_mode1 & boot_mode0 pin's leve is determined by NVCC_JTAG. so if NVCC_JTAG is 1.8V, BOOT_MODE1 & BOOT_MODE0 pins should be 1.8V IO.(2)SAI1's level is determined by NVCC_SAI1, BT_CFG  IO should be also 1.8V

>>问题2:如果不改变boot 配置电路 ， 调整imx8电源供电，VNCC_JTAG_、VNCC_SAI1供电采用3.3V,其余采用1.8V，具体如下下图所示，是否可行？。Yes, no porblem.  I think the way is better than above.

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Have a nice day!

NXP TIC weidong sun