Under-Voltage Lockout Sequencing for Multi-Rail Power Converters
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Solution Overview
Problem
In advanced process nodes below 28 nm, system-on-chips face challenges with power management as output voltages from power management systems can exceed voltage thresholds during hot plugging events, potentially damaging components.
Innovation Solution
A power managing system with a power converter circuit and under voltage lockout circuit that controls output voltages, rapidly decreasing the highest voltage to zero when a common voltage falls below a lockout threshold, and gradually decreasing the lowest voltage, ensuring different time intervals for voltage changes to prevent excessive voltage differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the power management system supplies output voltages simultaneously to all power converters, then the power distribution is efficient and fast, but the voltage difference between power converters may exceed the voltage threshold causing damage to system-on-chip
Solution Approach 1:
The under voltage lockout circuit detects the common voltage before distributing power to all converters and delays enabling the first power converter until after the second power converter has been enabled and stabilized. This preliminary voltage level check and sequential enabling approach prevents excessive voltage differences from occurring in the first place, resolving the contradiction between fast power distribution and voltage difference protection.
Solution Approach 2:
The power distribution is segmented into sequential phases: the second power converter is enabled first, followed by a delay period, then the first power converter is enabled. This temporal segmentation of the power distribution process ensures that voltage differences remain within safe thresholds while still achieving efficient overall power distribution.
2Volume of moving object
If the system uses advanced process nodes below 28 nm to reduce system-on-chip size, then the integration density is improved, but the circuit design becomes more challenging due to voltage management requirements
Solution Approach 1:
The under voltage lockout circuit acts as an intermediary between the power management system and the power converters. It monitors the common voltage level and controls the sequential enabling of power converters based on voltage thresholds, thereby simplifying the overall circuit design by providing automatic voltage management rather than requiring complex control logic in the advanced process node circuits themselves.
3Loss of time
If the system enables all power converters simultaneously during hot plugging, then the power-up time is reduced, but the voltage threshold may be exceeded causing system-on-chip damage
Solution Approach 1:
The system performs preliminary detection of the common voltage level before enabling power converters. By checking whether the common voltage exceeds the first threshold voltage, the system can safely enable converters in sequence rather than simultaneously, preventing damage while minimizing the overall power-up time loss.
Solution Approach 2:
The power converter enabling process is made dynamic and adaptive based on real-time voltage conditions. The under voltage lockout circuit continuously monitors the common voltage and adjusts the enabling sequence accordingly, allowing the system to achieve fast power-up when conditions permit while maintaining reliability when voltage thresholds are approached.
Data Source
AI summary
A power managing system and method are provided. When an under voltage lockout circuit determines that a common voltage of the power managing system is lower than a first lockout voltage, the under voltage lockout circuit outputs a first under voltage lockout signal for controlling one of a plurality of power converters that supplies a highest output voltage to rapidly reduce its output voltage to a zero value. Then, the under voltage lockout circuit outputs a second under voltage lockout signal for controlling another one of the power converters that supplies a lowest output voltage to gradually reduce its output voltage to the zero value.