Abstract: The disclosure relates an enhanced security feature that protects the data stored in an integrated circuit inside a device from reprogramming by software. A lock circuit, which resides outside the integrated circuit, provides a one-time programmable (OTP) solution that can be implemented using a fuse, a transistor, and a resistor, which are standard, off-the-shelf, discrete, board-level parts. After memory inside the integrated circuit has been programmed, the transistor can be turned on to blow the fuse, which permanently sets an external pin of the integrated circuit to a logical low voltage. The memory inside the integrated circuit is protected from further programming so long as the external pin has a logical low voltage. Since the fuse has been physically blown, the memory inside the integrated circuit is protected from undesirable changes by malicious software.