Patent ID: 8914907

Claim:
An electronic device, comprising: a key circuit that generates a key signal; a processor that generates an access signal; a storage unit that stores data; a clock signal generating circuit that generates a clock signal; and a protection circuit that generates an enable signal or a disable signal according to the key signal and the clock signal to control the storage unit to unlock or lock, the protection circuit transmitting the access signal to the storage unit to access the data when the storage unit is unlocked; wherein the protection circuit comprises a first NOT gate, a first delay unit, an AND gate, a second delay unit, a second NOT gate, a third NOT gate and an OR gate, an input end of the first NOT gate connects to the key circuit to receive the key signal and invert the key signal to an inverted key signal, the first delay unit connects to an output end of the first NOT gate and the clock signal generating circuit, the first delay unit delays the inverted key signal to a plurality of delay signals according to the clock signal, input ends of the AND gate connects to a plurality of output ends of the first delay unit to receive the delay signals, a first input end of the second delay unit connects to an output end of the AND gate, an input end of the second NOT gate connects to an output end of the second delay unit, an output end of the second NOT gate connects to a second input end of the second delay unit, an input end of the third NOT gate connects to the output end of the second delay unit, an output end of the third NOT gate generates an enable signal or a disable signal to control the storage unit to unlock or lock, and a first input end of the OR gate connects to the output end of the third NOT gate to receive the enable signal or the disable signal, a second input end of the OR gate connects to the processor to receive the access signal, and an output end of the OR gate connects to the storage unit.