Adaptive Reference Voltage Generator for Power Supply Over-Current Protection
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Solution Overview
Problem
Switching power supplies experience time delays and voltage drift in over-current protection due to non-ideal factors, leading to protection point voltage variations with input voltage changes, which affect the efficiency and reliability of power supply operations.
Innovation Solution
A current-level controlling device with an adaptive reference voltage generator that adjusts the reference voltage based on peak values of the current sense signal, ensuring the actual voltage for over-current protection matches the expected voltage, thereby reducing time delays and voltage drift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed reference voltage is used for over-current protection, then the protection mechanism is simple, but the protection point voltage drifts with input voltage changes
Solution Approach 1:
The reference voltage is changed from a fixed value to a dynamically adjustable value that adapts to input voltage changes. The control unit modifies the reference voltage based on the detected input voltage level, ensuring the protection point remains stable despite variations in input conditions.
Solution Approach 2:
A feedback mechanism is implemented where the control unit continuously monitors the input voltage and adjusts the reference voltage accordingly. This closed-loop control ensures that the protection point voltage remains consistent by compensating for input voltage variations through adaptive reference voltage adjustment.
2Speed
If a simple comparator is used to detect over-current, then the detection is fast, but time delay occurs in turning off the switch transistor
Solution Approach 1:
The control unit proactively adjusts the reference voltage before the over-current condition occurs by anticipating input voltage changes. This preliminary adjustment of the reference voltage level prepares the protection mechanism to trigger at the correct moment, reducing the effective time delay in switch transistor turn-off.
3Reliability
If the reference voltage is adjusted adaptively, then the protection point voltage stability improves, but the device complexity increases
Solution Approach 1:
The control unit is designed to perform multiple functions: it not only controls the switch transistor but also dynamically adjusts the reference voltage based on input voltage detection. This multi-functionality allows the system to maintain protection point stability without requiring entirely separate adjustment circuitry.
Data Source
AI summary
A current-level controlling device for a power supply includes a reception end for receiving a current sense signal, a reference voltage generator for generating a reference voltage, an adaptive reference voltage generator, coupled to the reference voltage generator and the reception end, for adjusting the reference voltage according to variation of peak values of the current sense signal, so as to generate an adaptive reference voltage, a comparator, coupled to the reception end and the adaptive reference voltage generator, for comparing the current sense signal and the adaptive reference voltage, to generate a comparison result, and a control unit, coupled to the comparator, for controlling a switch transistor of the power supply according to the comparison result.