Pull-Up Circuit Control for Overvoltage I/O Pads
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Solution Overview
Problem
Conventional pull-up circuits in integrated circuits are inadequate when dealing with input voltages higher than the power supply voltage, as they can be damaged due to excessive voltage levels, leading to malfunction and noise interference.
Innovation Solution
A pull-up device comprising a static pull-up circuit, an adjustment unit, and a control circuit, which includes PMOS transistors and a resistor, generates an adjustment signal to control the pull-up circuit, ensuring the input voltage is managed effectively even when higher than the supply voltage, preventing transistor damage and maintaining stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional pull-up circuit is used to maintain input voltage at a predetermined value, then noise interference is prevented, but the circuit cannot handle input voltages higher than the power supply voltage without damage
Solution Approach 1:
The patent introduces a control circuit as an intermediary between the I/O pad and the static pull-up circuit. This control circuit monitors the input voltage and dynamically adjusts the pull-up circuit's operation, enabling the system to safely handle input voltages higher than the power supply voltage while protecting the static pull-up circuit from damage.
Solution Approach 2:
The patent transforms the static pull-up circuit into a dynamic system by adding a control circuit that adjusts the pull-up strength based on input voltage conditions. The control circuit modifies the operation of the static pull-up circuit in real-time, allowing it to adapt to varying input voltage levels including those exceeding the power supply voltage.
2Adaptability or versatility
If the pull-up circuit is designed to handle higher input voltages, then voltage damage is prevented, but the circuit complexity increases
Solution Approach 1:
The control circuit serves multiple functions: it monitors input voltage levels, determines whether the input voltage exceeds the power supply voltage, and controls the static pull-up circuit accordingly. This multi-functionality allows the system to handle higher voltages without requiring separate protection circuits for each function, thereby limiting the increase in overall circuit complexity.
3Stability of the object's composition
If a static pull-up circuit is used to maintain stable input voltage, then noise resistance is improved, but the circuit cannot adapt to varying input voltage levels
Solution Approach 1:
The patent converts the static pull-up circuit into a dynamic system by introducing a control circuit that continuously monitors input voltage levels and adjusts the pull-up operation accordingly. This allows the circuit to maintain stable input voltage under normal conditions while adapting to handle higher voltage levels when they occur, resolving the contradiction between stability and adaptability.
Solution Approach 2:
The control circuit implements a feedback mechanism by monitoring the input voltage level and using this information to control the static pull-up circuit. When the input voltage exceeds the power supply voltage, the control circuit adjusts the pull-up strength to prevent damage while maintaining signal integrity, thereby providing both stability and adaptability.
Data Source
AI summary
A pull-up device coupled between an input/output (I/O) pad and a core circuit and has a static pull-up circuit, an adjustment unit, and a control circuit. The static pull-up circuit is coupled to the core circuit and receives a supply voltage. The adjustment unit is coupled to the I/O pad and generates an adjustment signal according to an input voltage of the I/O pad. The control circuit is coupled to the adjustment unit and the static pull-up circuit and controls the static pull-up circuit according to the adjustment signal.