Switching Regulator Quick-Start Circuit for Fast Mode Transitions
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Solution Overview
Problem
Conventional switching regulator circuits face challenges in transitioning efficiently from low-power to high-power modes, particularly in maintaining output voltage stability when load current increases rapidly, due to the time required for compensation capacitors to recharge.
Innovation Solution
The proposed switching regulator circuit incorporates a controller that manages the switching regulator's operation by enabling/disabling comparators and amplifiers based on power modes, along with a quick-start circuit and timer circuit to maintain capacitor charge and reduce transition time, ensuring stable operation during mode changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the switching regulator uses conventional compensation capacitor charging methods, then the circuit operates reliably in high-power mode, but the transition time from low-power to high-power mode is excessive due to capacitor recharge requirements
Solution Approach 1:
The patent applies preliminary action by maintaining the compensation capacitor charged state during low-power mode through a keep-charged circuit. The capacitor is pre-charged to a voltage higher than the threshold voltage before high-power mode activation, so when the mode switches, the capacitor is already ready to drive the PWM generator immediately, eliminating the recharge delay while ensuring reliable operation.
2Use of energy by moving object
If the switching regulator disables error amplifier and comparator in low-power mode to reduce consumption, then power consumption decreases, but the circuit cannot respond immediately when switching to high-power mode
Solution Approach 1:
The patent uses preliminary action by keeping the compensation capacitor charged during low-power mode through a dedicated keep-charged circuit, while disabling the error amplifier and comparator to save power. When switching to high-power mode, the pre-charged capacitor immediately drives the PWM generator, achieving fast response without requiring continuous operation of power-consuming components.
Solution Approach 2:
The patent introduces an intermediary element - the compensation capacitor - that decouples the power consumption of the error amplifier/comparator from the response speed requirement. The capacitor stores energy and maintains the necessary voltage level independently, allowing the main amplifying components to be disabled during low-power mode while still enabling immediate response when needed.
3Device complexity
If the switching regulator uses a single comparator for both low-power and high-power modes, then device complexity is reduced, but measurement precision deteriorates due to the high current range required
Solution Approach 1:
The patent applies segmentation by dividing the current sensing function into two separate comparators: a low-power comparator for detecting small currents in low-power mode, and a high-power comparator for detecting large currents in high-power mode. Each comparator is optimized for its specific current range, achieving high measurement precision in both modes while the controller intelligently selects which comparator to use based on the operating mode.
Data Source
Figure 1A
Figure 1B
Figure 1C~1D
AI summary
One example discloses a switching regulator circuit, comprising: a power supply input (Vin); a voltage reference (Vref); a power output (Vout); a high-side switch coupled between the power supply input (Vin) and the power output (Vout); a low-side switch coupled between a ground reference (GND) and the power output (Vout); a driver circuit coupled to the high-side switch and the low-side switch; a low-power comparator (COMP1) coupled to receive the voltage reference (Vref) and the power output (Vout); a high-power comparator (COMP2) having a first input and a second input; wherein the first input is coupled to a compensation capacitor (CC) and a first switch (SW1); wherein the second input is coupled to a current sense ramp; wherein the current sense ramp is coupled to the power output (Vout).