Switching Regulator Quick Response Circuit for Load Transients
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Solution Overview
Problem
Conventional switching regulators exhibit poor load transient response, leading to severe voltage undershoot and overshoot during changes in load current, particularly in CPU/GPU applications, due to limited feedback control and delayed phase activation in interleaving modes.
Innovation Solution
A switching regulator with a quick response (QR) method that includes a differentiator circuit to generate a differential signal from the output voltage, compared to a QR threshold, triggering adjustments in PWM signals to ensure concurrent power switch activation or deactivation for a QR period, thereby improving transient response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional feedback control is used in switching regulators, then the circuit structure remains simple, but the load transient response is poor causing severe voltage undershoot and overshoot
Solution Approach 1:
The differentiator circuit performs preliminary action by detecting voltage changes before they become significant undershoot or overshoot. The circuit generates a differential signal that triggers the QR mode in advance, allowing the power stage to respond proactively to load transients rather than reactively, thus improving transient response without requiring complex feedback control structures.
2Reliability
If high-capacitance output capacitors are used to reduce voltage undershoot and overshoot, then the transient response improves, but the manufacturing cost and circuit area increase
Solution Approach 1:
The invention substitutes the mechanical approach of using large physical capacitors with an electronic control approach. The differentiator circuit and QR control mechanism replace the passive energy storage function of large capacitors with an active control system that manages power delivery dynamically, achieving voltage stability without requiring large capacitance values and their associated area and cost.
3Temperature
If interleaving mode is used to distribute load current, then the thermal performance improves, but the phase activation delay worsens the transient response
Solution Approach 1:
The invention introduces dynamic control to the phase activation process. The differentiator circuit continuously monitors voltage changes and can dynamically adjust phase activation timing based on actual load conditions. This allows the system to maintain interleaved operation for thermal management while reducing activation delays during transients by triggering QR mode when voltage changes are detected, effectively decoupling thermal performance from transient response timing.
Data Source
AI summary
A switching regulator which has load transient quick response ability includes at least one power stage circuit and a control circuit. The control circuit includes a pulse width modulation (PWM) signal generation circuit and a quick response (QR) signal generation circuit. The PWM signal generation circuit generates a PWM signal according to an output voltage and a QR signal, to control a power switch of the corresponding power stage circuit, thus converting an input voltage to the output voltage. The QR signal generation circuit includes a differentiator circuit and a comparison circuit. The differentiator circuit performs a differential operation on a voltage sensing signal related to the output voltage, to generate a differential signal. The comparison circuit compares the differential signal with a QR threshold signal, such that when the differential signal exceeds the QR signal, the PWM signal generation circuit performs a QR procedure.