BUCK Regulator Switch Control Circuit for PSM-PWM Transition Stability
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Solution Overview
Problem
The existing BUCK circuit experiences significant output voltage ripples when switching between Pulse Skip Modulation (PSM) and Pulse Width Modulation (PWM) modes due to inadequate control of the error amplifier and compensation network, leading to instability and power consumption issues during light load conditions.
Innovation Solution
A switch control circuit that includes an error amplifier, a compensation network, and a control circuit with switches (from a first switch to a fifth switch) that are controlled by a single enable signal to manage the operating states of the error amplifier and compensation network, allowing the error amplifier to operate in amplification or voltage following states and the compensation network to operate in mutual or capacitance self-compensation states, respectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the error amplifier is closed in the PSM mode to reduce power consumption, then power consumption is reduced, but output voltage ripples become great and indeterminable when switching from PSM to PWM mode
Solution Approach 1:
The patent applies preliminary action by pre-charging the compensation capacitor through the third switch before mode switching occurs. This ensures that when transitioning from PSM to PWM mode, the compensation network already has the necessary voltage to prevent output voltage ripples, thus resolving the stability issue while maintaining power savings during PSM operation
Solution Approach 2:
The patent introduces an intermediary mechanism (the third switch and compensation capacitor) that mediates between the error amplifier's power consumption state and the output voltage stability requirement. This intermediary allows the system to achieve both low power consumption during PSM and stable output voltage during mode transitions
2Reliability
If the error amplifier is not closed in the PSM mode to maintain output voltage stability, then output voltage stability is improved, but power consumption increases
Solution Approach 1:
The patent uses preliminary action by charging the compensation capacitor before mode switching, which allows the error amplifier to be closed during PSM operation (saving power) while ensuring stability is maintained during the transition to PWM mode through the pre-charged compensation network
Solution Approach 2:
The patent applies dynamics by making the error amplifier's operating state dynamic - closed during PSM mode to save power, and opened during PWM mode to ensure stability. The switch control circuit dynamically adjusts the error amplifier's state based on the operating mode, optimizing both power consumption and stability
3Reliability
If switches are added to control the error amplifier and compensation network states, then output voltage ripples are reduced and stability is improved, but device complexity increases
Solution Approach 1:
The patent applies universality by designing the switch control circuit to perform multiple functions: controlling the error amplifier's on/off state, charging the compensation capacitor, and coordinating mode transitions. This multi-functional approach reduces the need for separate dedicated circuits for each function, thereby limiting the increase in device complexity while achieving improved stability
Data Source
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AI summary
Disclosed is a switch control circuit, including an error amplifier, a compensation network and a control circuit, wherein the compensation network is connected to an output end of the error amplifier; and the control circuit includes switches from a first switch to a fifth switch and is configured to control operating states of the error amplifier and the compensation network by controlling on/off states of switches from the first switch to the fifth switch. Further disclosed are switch control method, a regulator including the above switch control circuit as well as a computer storage medium.