Memory Management Unit Remapping OTP to MTP
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Solution Overview
Problem
One-time programmable (OTP) non-volatile memory cells are too small to be reprogrammable, while multiple-time programmable (MTP) cells are larger and more costly, necessitating a solution that provides reprogrammability without the size and cost increases of MTP cells.
Innovation Solution
A memory management unit (MMU) is introduced to manage OTP cells, allowing them to appear reprogrammable by remapping data to spare physical memory locations, eliminating the need for fully duplicative banks and reducing the size of the memory system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If MTP NVM cells are used to provide re-programmability, then re-programmability is improved, but memory cell size increases significantly
Solution Approach 1:
The memory system is divided into two distinct parts: OTP NVM cells for initial data storage and a separate mapping structure for remapping operations. This segmentation allows the small OTP cells to be combined with a lightweight mapping mechanism to achieve re-programmability without requiring large MTP cells throughout the entire memory array.
Solution Approach 2:
A mapping structure acts as an intermediary between the circuit and the OTP NVM cells. This mapping layer redirects access to spare physical memory locations, enabling the appearance of re-programmability while the underlying OTP cells remain small and non-reprogrammable.
2Adaptability or versatility
If MTP NVM cells are used to provide re-programmability, then re-programmability is improved, but manufacturing cost increases
Solution Approach 1:
The invention uses inexpensive OTP NVM cells as the primary storage medium, accepting that they can only be programmed once. The system compensates for this limitation through software-based remapping rather than using expensive MTP hardware, thereby reducing manufacturing costs while providing effective re-programmability.
Solution Approach 2:
Instead of physically duplicating OTP cell banks (which would increase manufacturing cost), the invention creates a logical copy through the mapping structure that redirects to spare locations. This virtual duplication achieves the same effect as physical redundancy without the associated manufacturing expense.
3Adaptability or versatility
If fully redundant OTP NVM banks are used to provide re-programmability, then re-programmability is improved, but memory system size increases
Solution Approach 1:
Rather than creating complete redundant copies of entire OTP banks, the invention uses partial redundancy with a mapping structure that selectively redirects only the necessary number of locations to spare cells. This partial action approach provides sufficient re-programmability for most applications without the overhead of full bank duplication.
Data Source
AI summary
Memory management units (MMUs) are disclosed. In one aspect, an MMU may have a first interface to a component. The first interface may receive one of a read of updated data from, and a write of updated data to, a virtual memory address. The virtual memory address may initially correspond to a first physical memory location in an only one time programmable (OTP) non-volatile memory (NVM). The MMU may have a remapping unit to remap a correspondence of the virtual memory address from the first physical memory location to a spare physical memory location. The MMU may also have a second interface to the OTP.NVM. The second interface may allow the updated data to be read from or written to the spare physical memory location of the OTP NVM. Methods performed by the MMUs, and methods and articles useful for manufacturing MMUs, are also disclosed.