APW11I1216-1a is a power supply unit designed by Bitmain for Antminer S21 Imm, which provides stable power to ensure the normal operation of the mining machine. The output voltage of this power supply is 12V-16V, and the input voltage is 380-415V AC. It has high efficiency, high stability, and a reliable protection mechanism and can maintain stable output during long-term operation. It adapts to the working environment of the miner. It has overvoltage protection, overcurrent protection, overheating protection, and other functions to prevent the miner from being damaged due to power problems.