Protection Register Array Lock Status Storage
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Solution Overview
Problem
As Flash memory becomes larger and more complex, existing methods for determining the lock status of protection registers in a group become impractical due to the number of associated cells exceeding system capability, making it difficult to implement additional protection registers without exceeding on-chip pump capacity.
Innovation Solution
The lock status of protection registers is stored in a word within the protection register array, allowing on-chip devices to determine the status without using fuses, by reading and decoding specific bits at a fixed address, enabling the program algorithm to continue or abort based on the lock status, even when the number of cells exceeds on-chip pump capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If additional protection registers are implemented in a protection register array, then security functionality and data protection capability are enhanced, but the number of associated cells exceeds on-chip pump capacity
Solution Approach 1:
The patent combines the lock status storage function with the existing protection register array structure. Instead of using separate fuse cells external to the array, the lock status bits are integrated directly into words within the protection register array itself. This merging allows the system to manage lock status for multiple protection registers without requiring additional dedicated storage cells outside the array capacity.
Solution Approach 2:
The protection register array words are designed to serve multiple functions: storing protection data and simultaneously storing lock status information. By encoding lock status bits within the same array structure that stores protection register data, the system achieves multi-functionality without increasing the total cell count, allowing the on-chip pump to operate within its capacity limits.
2Speed
If lock status is stored in fuses external to the protection register array, then lock status can be determined immediately upon device activation, but the method becomes impractical when the number of associated cells exceeds system capability
Solution Approach 1:
The patent merges the lock status storage location with the protection register array, eliminating the need for separate fuse arrays. This integration allows the system to determine lock status by reading from the same array structure that stores protection data, simplifying the overall device architecture while maintaining the capability to quickly determine lock status during operation.
Solution Approach 2:
The patent introduces a status bit encoding mechanism that acts as an intermediary between the protection register data and the lock status determination. By encoding lock status information within the array words themselves rather than requiring separate fuse reads, the system mediates the information retrieval process to work within the constraints of the on-chip pump capacity.
3Quantity of substance
If lock status is stored within the protection register array, then on-chip pump capacity constraints are satisfied, but the CUI does not know the lock status before the algorithm initiates
Solution Approach 1:
The patent implements a preliminary read operation of the lock status bits from the protection register array before the programming algorithm executes. This preliminary action allows the system to determine the lock status in advance, enabling the CUI to make informed decisions about whether to proceed with programming operations, thus recovering the information availability that was lost by moving storage into the array.
Solution Approach 2:
The system implements a feedback mechanism where the lock status bits read from the protection register array provide information back to the CUI. This feedback loop allows the controller to adjust its behavior based on the actual lock status, ensuring that programming operations are only attempted on unprotected registers while maintaining efficient use of the on-chip pump capacity.
Data Source
AI summary
A protection register array in which the lock status of the protection register is stored outside of the array. An initial verify function is used to read lock status.