PLD I/O Bus Protection Using Cascode Voltage Control
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Solution Overview
Problem
Programmable logic devices (PLDs) face challenges in protecting input/output (I/O) bus supply voltages during power on sequences, as they can vary widely and may exceed the operational tolerance of I/O transistors, leading to reliability issues over time.
Innovation Solution
Implementing a bus protection control signal generator and a cascode transistor arrangement to manage I/O bus supply voltages, ensuring all transistor voltages remain within acceptable operational limits, and reducing power leakage and heating during operational modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If I/O bus supply voltage is allowed to vary widely during power on sequence, then adaptability to different user devices is improved, but reliability of I/O transistors deteriorates due to voltage exceeding operational tolerance
Solution Approach 1:
The patent introduces protection circuitry as an intermediary between the I/O bus and the I/O transistors. This protection circuitry includes voltage detection mechanisms and control logic that monitor the I/O bus supply voltage and prevent it from exceeding the operational tolerance of the I/O transistors during power-on sequences, thereby protecting the transistors while allowing the I/O bus to support wide voltage ranges for different user devices
Solution Approach 2:
The patent dynamically changes the operational parameters of the I/O transistors based on the detected I/O bus supply voltage. When the voltage is within the safe operational range, the transistors are enabled to operate normally. When the voltage exceeds the tolerance threshold during power-on, the protection circuitry adjusts the transistor operating parameters (such as gate voltage) to prevent damage, thus adapting the transistor behavior to the current voltage conditions
2Adaptability or versatility
If I/O transistors are designed to tolerate higher voltages, then adaptability to different bus supply voltages is improved, but power leakage and heating increase during operational modes
Solution Approach 1:
The patent employs dynamic control of the I/O transistors through protection circuitry that continuously monitors the I/O bus supply voltage and adjusts the transistor operating state accordingly. During normal operation at safe voltages, the transistors operate efficiently with minimal leakage. During power-on sequences with potentially harmful voltages, the protection circuitry dynamically switches the transistors to a protected state, preventing power leakage and heating while maintaining adaptability to different voltage standards
Data Source
AI summary
Systems and methods for providing external bus protection for programmable logic devices (PLDs) are disclosed. An example system includes a programmable I/O bus configured to interface with a user device over an external bus interface coupled to a PLD; a bus protection circuit arrangement integrated with the programmable I/O interface and configured to provide I/O bus supply voltage protection for the programmable I/O interface; and a bus protection control signal generator. The bus protection control signal generator generates a default bus protection control signal for the bus protection circuit arrangement of the PLD prior to completion of a power ramp performed by the user device; an intermediate bus protection control signal for the PLD prior to completion of loading a PLD configuration into a PLD fabric of the PLD; and an operational bus protection control signal for the PLD.