Adjustable Output Drive Strength for Multi-Die Status Bus Contention
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Solution Overview
Problem
In multi-die flash memory packages, the existing Read Status and Read Status Enhanced commands lead to bus contention issues due to unpredictable data outputs when multiple dies have different statuses, causing potential data loss and inefficiencies in determining the true status of the package.
Innovation Solution
The implementation of a method to manage drive parameters for each die, adjusting output drive impedance and strength through enabling or disabling transistors in the input/output drive circuitry, allowing for clear indication of active or inactive states on a shared bus without additional commands, thereby resolving bus contention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Read Status Enhanced command is used to read each die individually, then measurement precision of status is improved, but device complexity and time consumption increase due to requiring minimum one command per die
Solution Approach 1:
The patent changes the drive strength parameter of the output buffer based on the selected command type. When Read Status Enhanced is selected, the output buffer is configured with first drive strength to enable individual die reading. When Read Status is selected, the output buffer is configured with second drive strength (stronger than first) to override individual die outputs and indicate package-level status, thereby resolving the contradiction between measurement precision and command complexity
Solution Approach 2:
The output buffer's drive strength is made dynamic rather than fixed. The controller dynamically adjusts the drive strength based on the selected command, allowing the same hardware to support both individual die reading (Read Status Enhanced) and package-level status reading (Read Status) without requiring separate hardware paths for each function
2Device complexity
If Read Status command is used to read status of all dies, then device complexity is reduced, but reliability deteriorates due to unpredictable bus outputs when multiple dies have different statuses
Solution Approach 1:
The output buffer acts as an intermediary between the individual die outputs and the common bus. When Read Status command is selected, the output buffer is configured with stronger drive strength to override the outputs from individual dies, effectively mediating the conflict and ensuring that the bus reflects the intended package-level status rather than unpredictable individual die states
Solution Approach 2:
The drive strength parameter of the output buffer is changed based on the command type. For Read Status command, the buffer is configured with enhanced drive strength that allows it to dominate the bus, ensuring reliable package-level status indication even when individual dies have conflicting or different status states
3Reliability
If stronger drive strength is used on the common bus, then reliability of status indication is improved, but loss of information increases when multiple dies have different statuses
Solution Approach 1:
The output buffer's drive strength is dynamically adjusted based on the selected command. When Read Status Enhanced is selected, the buffer uses first drive strength to allow individual die outputs to be read. When Read Status is selected, the buffer switches to second drive strength to override individual outputs and indicate package-level status, thereby dynamically adapting to avoid information loss while maintaining reliability
4Measurement precision
If individual die status is read separately using Read Status Enhanced, then measurement precision is improved, but loss of time increases due to requiring multiple commands
Solution Approach 1:
The output buffer's drive strength parameter is changed based on the command type to enable efficient status reading. When Read Status Enhanced is selected, the buffer is configured with first drive strength that allows precise individual die reading. When Read Status is selected, the buffer switches to second drive strength to provide package-level status in a single command, reducing the time required for status determination while maintaining measurement precision when needed
Data Source
AI summary
Apparatus, methods, and systems are disclosed, such as those involving a multi-die device having a common bus to indicate a state of each of a die of a multi-die device and that provides the state of all of the dice at a common output. Such a multi-die device can comprise two or more dice in a multi-die package, wherein each of said dice has a first drive parameter when indicating a first state and a second drive parameter when indicating a second state. When the first drive parameter of the two or more dice is at a value such that when one or more of said two or more dice is in the first state, said common output can indicate that all of the dice in the multi-die device are in the first state.