This Letter presents a self-controlled physical unclonable function (PUF) circuit and its application in encrypting on-chip memories of IC bank cards. The PUF circuit is based on cross-coupled NAND gates. Voting and Hamming code address the stability of its outputs. The Monte Carlo simulation and field-programmable gate array board are used for verification. The Voting method improves the error rate 79%. The Hamming codes and convertor can correct every error bits of PUF outputs. The PUF outputs, data address and time-stamp are encrypted by SM4 (Chinese block cipher algorithm standard) to generate KEY. The data does XOR with the KEY.