OTP sector double protection for a simultaneous operation flash memory
AssigneesAdvanced Micro Devices, Inc., Fujitsu Limited
InventorsYasushi Kasa, Johnny Chung-Lee Chen, Guowei Wang, Tiao-Hua Kuo
Life of this patent
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Abstract
A simultaneous operation flash memory capable of providing double protection to An OTP sector. The preferred simultaneous operation flash memory comprises an OTP write-protect CAM, which is in a programmed state if the OTP sector is write-protected. In addition, the preferred simultaneous flash memory further includes an OTP sector lock CAM that is electrically connected with the OTP write-protect CAM. The OTP sector lock CAM is used to lock the OTP write-protect CAM in the programmed state, which, in turn, will designate the OTP sector as read only.
Claims25
A simultaneous operation flash memory capable of providing double protection to an OTP sector, comprising:
- an OTP sector write-protect CAM, wherein said OTP sector write-protect CAM is capable of designating said OTP sector as write-protected;
- and
- an OTP sector lock CAM electrically connected with said OTP sector write-protect CAM, wherein said OTP sector lock CAM locks said OTP write-protect CAM in a programmed state.
A simultaneous operation flash memory (10) with dual protection for an OTP sector (26), comprising:
- at least one decoder circuit (36) for decoding a plurality of input signals from a plurality of address lines (22), wherein said decoder circuit (36) generates a respective output signal when said plurality of input signals equals a predetermined set of values;
- an OTP sector write-protect CAM (34) electrically connected with said respective output of said decoder circuit (36), wherein the state of said OTP sector write-protect CAM (34) is used to designate said OTP sector (26) as write-protected;
- and
- an OTP sector lock CAM (30) electrically connected with said OTP sector write-protect CAM (34), wherein said OTP sector lock CAM (30) is capable of locking said OTP sector write-protect CAM (34) designating said OTP sector (26) as write-protected.
A method of providing dual protection for an OTP sector (26) in a simultaneous operation flash memory (10), comprising the steps of:
- programming a predetermined amount of data in said OTP sector (26);
- write-protecting said OTP sector (26) with an OTP sector write-protect CAM (34);
- and
- locking said OTP sector write-protect CAM (34) in a write-protect state with a OTP sector lock CAM (30).
Dependencies are inferred from the claim text.