Power Supply Clamping Circuit for Fast Rush Voltage Response
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Solution Overview
Problem
Conventional power supply circuits face challenges in effectively clamping output voltages during large rush voltage events, which can lead to excessive voltage application to downstream circuit units, compromising circuit safety and stability.
Innovation Solution
The power supply circuit incorporates a first transistor configured as a source follower, an amplifier circuit to generate a control signal based on a voltage difference, and a capacitor to rapidly respond to voltage changes, ensuring high-speed clamping of output voltages by controlling the gate signal and utilizing a charge pump circuit in the second embodiment for enhanced control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a conventional power supply circuit is used, then the circuit structure is simple, but the response speed to rush voltage is slow and cannot effectively clamp output voltage
Solution Approach 1:
The capacitor is pre-charged to a predetermined voltage level before rush voltage occurs. When rush voltage happens, the capacitor immediately discharges to clamp the output voltage, providing preliminary protective action that achieves fast response without complex control circuits.
Solution Approach 2:
The capacitor acts as an intermediary element between the power supply and output. It mediates the voltage surge by absorbing excess energy and releasing it controlledly, enabling fast clamping response while keeping the overall circuit structure relatively simple.
2Speed
If a fast response clamping circuit is implemented, then the response speed improves, but the phase margin of the amplifier circuit decreases
Solution Approach 1:
The clamping function is segmented from the main power supply circuit into a separate capacitor-based protection circuit. This segmentation allows the clamping operation to occur independently with fast response, while the main amplifier circuit maintains its stability and phase margin without being directly affected by the clamping action.
3Productivity
If the capacitor voltage follows output voltage, then the circuit operation is simple, but the clamping response is delayed during rush voltage
Solution Approach 1:
The capacitor is pre-charged to a predetermined voltage level that is higher than the normal output voltage but lower than the dangerous rush voltage level. This preliminary charging enables the capacitor to immediately clamp the output voltage when rush voltage occurs, eliminating the delay that would occur if the capacitor had to charge up during the event.
Data Source
AI summary
A power supply circuit in an embodiment includes a first transistor controlled to be turned on and off by a control signal supplied to a gate to output an output voltage following a predetermined voltage, a second transistor, one end of a current path of which is connected to an input terminal for supplying a power supply voltage, the second transistor outputting the predetermined voltage according to the control signal, and an amplifier circuit configured to amplify a voltage difference between a reference voltage and the predetermined voltage, and output the voltage difference as the control signal.