Hot Swap Decoupling for Power Bus Noise Reduction
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Solution Overview
Problem
Hot swap operations in power systems often result in power bus noise and voltage fluctuations due to uncontrolled inrush currents and capacitive loads, which existing technologies fail to mitigate effectively without introducing additional losses or dependencies on noise immunity limitations.
Innovation Solution
A hot swap decoupling apparatus that selectively disconnects and reconnects decoupling capacitors based on a power good signal, allowing for controlled damping and reduced noise during hot swap events while maintaining noise immunity during normal operation by using a switching device and a hot swap control circuit to manage the capacitive load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If decoupling capacitors are connected across the power bus to smooth voltage, then voltage stability is improved, but power bus noise increases during hot swap events
Solution Approach 1:
The patent applies the dynamics principle by making the decoupling capacitor configuration dynamic rather than static. The system automatically adjusts the capacitor connection state based on operating conditions: capacitors are connected during normal operation to provide voltage stability, and disconnected during hot swap events to reduce noise. This is achieved through hot swap detection circuitry that controls the capacitor switching elements to change the circuit topology in response to detected hot swap conditions.
2Object-affected harmful factors
If additional serial components are added to reduce noise, then noise immunity is improved, but device complexity and power losses increase
Solution Approach 1:
The patent applies the extraction principle by removing the problematic decoupling capacitors from the power bus during hot swap events rather than adding noise-filtering components. Instead of introducing additional serial components to block noise, the system extracts the noise-generating capacitors from the circuit during critical hot swap operations, thereby reducing noise immunity requirements while avoiding increased complexity.
3Stability of the object's composition
If decoupling capacitors remain connected during hot swap, then voltage smoothing is maintained, but inrush current and voltage fluctuations increase
Solution Approach 1:
The patent applies preliminary anti-action by proactively disconnecting the decoupling capacitors before or during the hot swap event to prevent the harmful interaction between capacitor charging and inrush current. This preemptive action eliminates the voltage fluctuations and reliability issues that would occur if capacitors remained connected, while the system subsequently restores capacitor connection after the hot swap completes to resume voltage smoothing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution reduces power bus noise during hot swap events, eliminates the need for additional serial components, and enhances power distribution flexibility by controlling the RC time constant through FET selection, thereby minimizing power losses and voltage fluctuations.
Implementation Method 1
a switching device having first and second terminals and an control input, the first and second terminals being in electrical connection when the switching device is in a closed state and being in electrical isolation from each other when the switching device is in an open state
Implementation Method 2
a capacitive load having first and second terminals, the first terminal configured to be in electrical connection with a first conductor of a power bus
Implementation Method 3
a hot swap control circuit configured to be in electrical connection with a load that is powered by the first and second conductors of the power bus, and that monitors an electrical state of the load while the load transitions from an unpowered state to a fully powered state
Data Source
AI summary
An apparatus for selectively connecting a decoupling capacitor in parallel with a load on a power bus during a hot swap power up. In an aspect, an apparatus includes a capacitive coupling connected to a hot swap control circuit and that capacitively couples first and second power conductors when the output of the hot swap control circuit indicates a monitored load has attained a voltage threshold.