I/O Output Driver Voltage Selection for Stable Loop Delay
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Solution Overview
Problem
Integrated circuits face communication failures due to variations in supply voltage causing increased total loop delay, which exceeds the maximum allowed by serial interface protocols, leading to potential underdrive situations and short circuits.
Innovation Solution
Incorporating a maximum voltage generator that selects and supplies the higher of the core supply voltage and the I/O supply voltage to the I/O transmitter circuitry, ensuring sufficient voltage for maintaining a small total loop delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the I/O supply voltage drops below the core supply voltage due to voltage variations, then the I/O transmitter circuitry cannot drive output data with sufficient speed, but using a fixed voltage supply would simplify the power management circuitry
Solution Approach 1:
The patent introduces a maximum voltage generator as an intermediary component that receives both the core supply voltage and I/O supply voltage, compares them, and outputs the higher voltage to the I/O transmitter circuitry. This mediator ensures the transmitter always receives sufficient voltage without requiring complex external voltage regulation or switching circuitry, thus maintaining communication reliability while keeping the overall device complexity manageable.
Solution Approach 2:
The maximum voltage generator is integrated within the I/O transmitter circuitry itself, allowing the circuit to self-regulate its supply voltage by automatically selecting the higher of the two available voltage sources. This self-service approach eliminates the need for external voltage monitoring and switching logic, reducing overall system complexity while ensuring reliable operation.
2Speed
If the I/O supply voltage is kept high to ensure fast data transmission, then the total loop delay remains within protocol limits, but power consumption increases
Solution Approach 1:
The patent applies partial action by providing high voltage only to the I/O transmitter circuitry when needed for fast data transmission, while the core logic circuitry operates at its normal lower voltage. The maximum voltage generator selectively applies the higher voltage only to the transmitter portion that requires it, avoiding unnecessary power consumption in other circuit blocks that do not need high-speed operation.
3Reliability
If voltage compensation circuitry is added to maintain stable loop delay, then communication failures are prevented, but the device complexity increases
Solution Approach 1:
The patent merges the voltage compensation function directly into the existing I/O transmitter circuitry by integrating the maximum voltage generator within the transmitter block. This combination approach provides voltage compensation to maintain reliable communication without adding separate, standalone compensation circuits, thus minimizing the increase in overall device complexity while ensuring communication failures are prevented.
Data Source
AI summary
An integrated circuit includes an output pad, and I/O driver that drives data to the output pad, and a predriver that controls the I/O driver. The integrated circuit includes maximum voltage generator that receives a first supply voltage and a second supply voltage and outputs to the predriver a maximum voltage corresponding to the higher of the first supply voltage and the second supply voltage.