Voltage Regulator Overshoot Detection With Diode Braking
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Solution Overview
Problem
Existing voltage regulation circuits face challenges in managing rapid reductions in load power, leading to significant voltage overshoots that require large capacitors, occupying significant circuit space and potentially causing damage.
Innovation Solution
A semiconductor device with a voltage regulator circuit that includes a feedback circuit to control a transistor, using comparators and logic circuits to detect overshoots and open the transistor as a diode brake, reducing the rate of energy discharge to a capacitor, thereby minimizing overshoot and allowing for smaller capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a voltage regulator circuit uses traditional feedback control without overshoot detection, then the circuit structure is simpler, but voltage overshoot increases significantly when load power rapidly decreases
Solution Approach 1:
The feedback circuit performs preliminary detection of voltage overshoot conditions by comparing the output voltage feedback signal with the reference voltage before the overshoot fully develops. When the feedback voltage exceeds the reference voltage indicating an overshoot condition, the circuit proactively activates the second transistor to discharge the inductor energy, preventing the overshoot from reaching damaging levels rather than reacting after the overshoot occurs
Solution Approach 2:
The circuit implements a feedback mechanism where the output voltage is continuously monitored through a feedback network (resistors R1 and R2) that feeds back a portion of the output voltage to the comparator. This feedback loop enables real-time detection of voltage deviations from the reference level, allowing the control system to adjust the transistor switching states to maintain voltage within acceptable ranges and prevent harmful overshoot conditions
2Reliability
If a larger capacitor is used to handle voltage overshoot, then voltage regulation stability improves, but circuit footprint increases significantly
Solution Approach 1:
The invention converts the potentially harmful inductor energy that causes voltage overshoot into a beneficial controlled discharge mechanism. By detecting overshoot conditions and actively controlling the second transistor to discharge the inductor energy through a controlled path, the circuit transforms the harmful energy release into a controlled process that prevents overshoot damage, allowing the use of smaller capacitors while maintaining stability
Solution Approach 2:
The circuit dynamically changes the operating parameters of the transistor switching states based on the detected voltage conditions. When overshoot is detected (feedback voltage exceeds reference voltage), the control logic changes the state of the second transistor from off to on, creating a controlled discharge path that alters the energy dissipation characteristics and enables stable regulation with smaller capacitor values
3Duration of action of stationary object
If the second transistor remains closed during load reduction, then continuous current flow is maintained, but voltage overshoot increases and potential damage occurs
Solution Approach 1:
The circuit dynamically adjusts the switching state of the second transistor based on real-time voltage conditions detected by the feedback circuit. Rather than maintaining a fixed closed state, the transistor's state changes from closed to open when overshoot conditions are detected (feedback voltage exceeds reference voltage), creating a dynamic response that prevents harmful overshoot while managing the inductor energy discharge in a controlled manner
Data Source
AI summary
A voltage regulator feedback circuit includes a first comparator, a second comparator and a logic circuit. The first comparator is configured to generate an overshoot signal based on a comparison of a voltage regulation target signal to a feedback voltage signal. The second comparator is configured to generate a forward current signal based on a comparison of the current sense amplifier voltage to a reference voltage. The logic circuit is configured to generate a breaking signal based on the overshoot signal and the forward current signal. A gate signal of a transistor connected between a second end of the inductor and a reference ground is generated based at least in part on the breaking signal and is configured to cause the transistor to open based at least in part on the breaking signal having a true value.