OTP Memory Circuit Power Switch Isolation
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Solution Overview
Problem
One-time programmable (OTP) memory cells are vulnerable to accidental programming during ungraceful power-down events, leading to irreversible data corruption and potential safety issues, especially in devices like medical equipment or vehicles, due to the lack of effective protection mechanisms.
Innovation Solution
Implementing an OTP memory circuit with internal power switches that decouple memory cells from programming voltage during power-down events, using a shared voltage regulator and redundant protection mechanisms to prevent accidental programming, thereby maintaining the memory in a non-program state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate voltage regulator is used for the OTP memory array to isolate it from other device circuits, then the reliability of OTP memory cells is improved, but the device complexity and cost increase
Solution Approach 1:
The patent combines the OTP memory array with the main device circuits under a shared voltage regulator, eliminating the need for a separate voltage regulator. Internal power switches are used to provide protection while sharing the common voltage regulator, thus reducing device complexity and cost while maintaining reliability through the switch-based isolation mechanism.
Solution Approach 2:
The patent introduces internal power switches as intermediary elements between the OTP memory array and the shared voltage regulator. These switches act as mediators that can isolate the OTP memory cells from programming voltage during power-down events, providing protection without requiring a separate voltage regulator, thus resolving the contradiction between reliability and device complexity.
2Reliability
If internal power switches are used to decouple OTP memory cells from programming voltage during power-down events, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The patent segments the power supply control into multiple internal power switches that can independently control different portions of the OTP memory array. This segmentation allows selective isolation of memory cells during power-down events, providing targeted protection while managing complexity through modular switch control rather than a single complex isolation mechanism.
3Reliability
If OTP memory cells are protected during power-down events, then the reliability is improved, but the manufacturing cost increases
Solution Approach 1:
The patent merges the protection function into the existing OTP memory array design by incorporating internal power switches that share the common voltage regulator. This approach eliminates the need for separate protection circuits and additional voltage regulators, thereby reducing manufacturing complexity and cost while maintaining reliable protection against accidental programming during power-down events.
Data Source
AI summary
[0071] In a particular embodiment, an apparatus includes a one- time programmable (OTP) memory circuit (324) configured to be responsive to a programming voltage (308). The OTP memory circuit includes an OTP memory array (220) including OTP memory cells, a first power switch (326) configured to decouple the OTP memory array (220) from the programming voltage (308), and a second power switch (328) configured to decouple a subset of the OTP memory cells from the programming voltage (308). Control logic (216) controls the power switches (326, 328) and is configured to maintain the OTP memory array (220) in a non-program state during a power-down event