Adaptive POR Generator for Variable Supply Ramp Timing
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Solution Overview
Problem
Programmable logic devices (PLDs) face challenges in ensuring reliable power-on-reset signals during varying supply voltage ramp rates, which can lead to malfunction or damage, especially when different components turn on at different times, requiring adaptive solutions to manage power supply slew rates effectively.
Innovation Solution
An adaptive power-on-reset (POR) signal generator that measures the ramp rate of the supply voltage and generates a POR signal coincident with the supply voltage reaching its nominal operating voltage, using a counter to determine the appropriate delay based on the ramp time between selected threshold voltages, allowing for flexible operation across different power supply conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed delay is used for power-on-reset signal generation, then the device complexity is reduced, but the reliability deteriorates due to inability to adapt to varying supply voltage ramp rates
Solution Approach 1:
The POR signal generator uses a variable delay mechanism that adapts to different supply voltage ramp rates. The delay is determined by measuring the actual ramp rate of the supply voltage and dynamically adjusting the POR signal assertion timing accordingly, rather than using a fixed delay. This dynamic adaptation ensures reliable operation across varying power supply conditions while managing device complexity through efficient measurement and control logic.
2Adaptability or versatility
If components are allowed to turn on at different times to match their specific requirements, then the adaptability is improved, but the device complexity increases due to need for coordinated control
Solution Approach 1:
The system measures the actual supply voltage ramp rate and uses this feedback information to determine the appropriate timing for asserting the POR signal. This feedback-based approach allows the system to adapt to different power supply conditions and component requirements without requiring complex pre-programmed sequences or multiple independent control circuits. The measurement result directly controls the delay timing, enabling coordinated power-on of components based on actual voltage conditions.
3Productivity
If the POR signal is generated too early, then the productivity is improved by faster system startup, but the reliability deteriorates due to premature turn-on of circuitry
Solution Approach 1:
The system performs a preliminary measurement of the supply voltage ramp rate before determining the POR signal timing. By measuring the actual ramp characteristics in advance, the system can calculate the optimal delay period needed to ensure the voltage reaches safe levels before circuitry is activated. This preliminary measurement approach enables the system to minimize startup time while ensuring reliable protection against premature turn-on, as the delay is precisely tailored to the measured voltage conditions.
Data Source
AI summary
Systems and methods for providing adaptive power on reset (POR) signals for use with programmable logic devices (PLDs) and/or other semiconductor devices are disclosed. An example adaptive POR signal generator includes a logic device configured to detect a first supply voltage ramp traversal across a first threshold ramp voltage, detect a second supply voltage ramp traversal across a second threshold ramp voltage, and generate a POR signal based, at least in part, on a nominal operating voltage associated with the power supply and/or the supply voltage and/or on a ramp time associated with the first and second supply voltage ramp traversals. The second threshold ramp voltage is higher than the first threshold ramp voltage and the first and second threshold ramp voltages are lower than the nominal operating voltage.