Dynamic Overvoltage Protection in Voltage Regulators
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Solution Overview
Problem
Voltage regulators face challenges in maintaining stable output voltage across a wide range of load currents, leading to potential device failure due to excessive voltage drops, especially in high dynamic load conditions.
Innovation Solution
A circuit that dynamically adjusts the cascode device gate voltage based on the regulator output load current, using a level shifter to normalize the voltage drop and include additional transistors for overvoltage protection during power supply ramp-up, ensuring the regulator pass gate drain voltage remains stable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If overvoltage protection is implemented by dropping voltage from supply to tolerable range, then transistor protection from overvoltage is improved, but voltage drop varies significantly causing pass gate drain voltage to collapse at high load currents
Solution Approach 1:
The patent applies dynamics by making the cascode device gate voltage adjustable rather than fixed. The gate voltage is dynamically tuned based on operating conditions (load current levels) to maintain optimal voltage drop normalization. This allows the protection circuit to adapt to varying load conditions and prevent pass gate drain voltage collapse at high currents while maintaining overvoltage protection reliability
Solution Approach 2:
The patent changes the gate voltage parameter of the cascode device to optimize performance. By adjusting the gate voltage, the voltage drop across the cascode device is normalized, which stabilizes the pass gate drain voltage. This parameter adjustment resolves the contradiction between providing overvoltage protection and maintaining voltage stability across different load conditions
2Reliability
If cascode device gate voltage is increased to protect from overvoltage, then overvoltage protection is improved, but voltage drop increases causing regulator output to collapse at high load currents
Solution Approach 1:
The patent uses dynamic adjustment of the cascode device gate voltage to balance overvoltage protection with power delivery. The gate voltage is tuned to achieve normalized voltage drop, which prevents both overvoltage damage and output voltage collapse. This dynamic approach allows the system to maintain both protection reliability and adequate power output across the full load current range
3Reliability
If voltage drop across cascode device is increased for protection, then transistor safety is improved, but regulator output voltage stability deteriorates under dynamic load conditions
Solution Approach 1:
The patent changes the gate voltage parameter to normalize the voltage drop across the cascode device. This parameter optimization ensures that the voltage drop provides adequate protection while maintaining regulator output voltage stability under dynamic load conditions. The tuned gate voltage prevents both transistor damage and output voltage collapse
Data Source
AI summary
A system includes a first transistor having a drain and source connected between a supply voltage and an output of a voltage regulator. A gate of the first transistor receives a first gate voltage. The system includes a second transistor having a drain and source connected between the supply voltage and the drain of the first transistor. The second transistor protects the first transistor from excessive voltage. The system includes a level shifter connected between a gate of the second transistor and a gate of the first transistor. The level shifter produces a level-shifted gate voltage for the second transistor that is based on the first gate voltage and that is proportional to an output load current output at the source of the first transistor.