Power Up Detection in Non-Volatile Memory Devices
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Solution Overview
Problem
Existing power up detection systems for non-volatile memories, such as anti-fuse memory devices, face challenges in reliably confirming completion of power up due to variables like operating temperature, which can lead to unstable voltage levels affecting proper device operation.
Innovation Solution
A power up detection method involving reading a test word from a ROM row and comparing it to predetermined data, followed by reading and comparing user data at different times to ensure matching, with repeated detection if mismatches are found, ensuring the memory device has reached a stable power state for normal operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple voltage level detection method is used, then the detection circuit is simple, but the reliability of power up detection is insufficient due to temperature variables affecting voltage stability
Solution Approach 1:
The patent performs preliminary actions by reading data from the memory array multiple times before confirming power up completion. The system reads a first set of data, then reads a second set of data after a predetermined time period, and compares them to ensure stability. This preliminary multi-read approach ensures that voltage fluctuations during power up do not cause false detection results, thereby improving reliability without significantly increasing circuit complexity.
2Speed
If voltage detection is performed immediately after power application, then the detection speed is fast, but the voltage levels may not have stabilized leading to incorrect detection results
Solution Approach 1:
The patent implements periodic action by performing data reads at predetermined time intervals during the power up sequence. The system reads data at an initial time, waits for a predetermined time period, then reads again and compares the results. This periodic sampling approach allows the system to detect voltage stabilization accurately while maintaining reasonable detection speed, as the time period is optimized to be the minimum necessary for stability verification.
3Reliability
If multiple data reads and comparisons are performed to ensure stability, then the detection accuracy is improved, but the time required for power up detection increases
Solution Approach 1:
The patent applies self-service by utilizing the memory array's existing data and read capabilities to perform the stability verification. Instead of requiring external test equipment or additional dedicated test circuits, the system uses its own operational resources (memory cells, read circuitry, and data paths) to detect power up completion. This approach minimizes additional time overhead since the memory device is already performing read operations as part of its normal functionality, and the comparison logic uses existing comparator circuits.
Data Source
AI summary
A power up detection method for a memory device and a memory device are disclosed. In a first phase, a test word is read from a read-only memory (ROM) row of a memory array of the memory device, and the test word is compared to predetermined ROM row data. If the test word matches the predetermined ROM row data, a second phase may be performed. In the second phase, first user data is read from a user-programmed row of the memory array at a first time. Second user data is read from the user-programmed row of the memory array at a second time different from the first time. The first user data is compared to the second user data. Successful power up of the memory device is determined when the first user data matches the second user data.