Buck Circuit Fast Transient Response Mechanism
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Solution Overview
Problem
Conventional buck circuits experience slow discharge of excess current when the external load transitions from a heavy to a light load state, leading to undesirable voltage overshoot and instability.
Innovation Solution
A buck circuit with a fast transient response mechanism, comprising a high side MOS, a low side MOS, a transient control module, and an operation control module, where the transient control module is enabled to rapidly discharge excess current by turning on the low side MOS when the load state changes, using a comparator and logic to manage the MOS gates and provide a discharging path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the conventional buck circuit design is used, then the circuit structure is simple, but the discharge process is slow when the external load transitions from heavy to light load state
Solution Approach 1:
The transient control module detects the load transition state in advance and proactively activates the low side MOS to create a discharge path before the voltage overshoot becomes severe. The comparator monitors the voltage difference between nodes and triggers the discharge mechanism preemptively when the external load transitions from heavy to light load state, preventing the slow discharge problem of conventional circuits.
2Reliability
If the transient control module is added to enable fast discharge, then the discharge speed is improved, but the device complexity increases
Solution Approach 1:
The transient control module acts as an intermediary control mechanism that coordinates between the operation control module and the low side MOS. It includes a comparator that monitors voltage differences and control logic that determines when to activate the discharge path, serving as a mediator to enable fast transient response while maintaining systematic control over the buck circuit's operation.
Solution Approach 2:
The comparator continuously monitors the voltage difference between the connection point of the MOS transistors and the output node, providing feedback to the transient control module. When the voltage difference exceeds a threshold during load transitions, the feedback signal triggers the low side MOS to activate, creating a discharge path that stabilizes the output voltage and improves transient response reliability.
3Ease of operation
If the low side MOS is turned on rapidly to discharge excess current, then the voltage overshoot is reduced, but the control complexity increases
Solution Approach 1:
The transient control module autonomously detects load transitions and controls the discharge process without requiring external intervention. The comparator automatically monitors voltage conditions and the control logic independently determines when to activate the low side MOS, making the circuit self-regulating during transient conditions and simplifying overall system operation.
Data Source
AI summary
A buck circuit having a fast transient response mechanism is provided. The buck circuit comprises a high side MOS, a low side MOS, a transient control module and an operation control module. The low side MOS is connected to the high side MOS at a connection point for generating an output voltage to an external load according to an input voltage from the high side MOS. The operation control module controls the operation of the high and the low side MOS according to the output voltage when the external load is in a heavy load state such that the transient control module is disabled. When the external load turns from the heavy load state to a light load state such that the output voltage raises over a predetermined level, the transient control module is enabled to turn on the low side MOS for discharging to pull down the output voltage.