Driving Stage Circuit Adaptive Clamping Levels
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Solution Overview
Problem
Existing driving stage circuits face challenges in simultaneously meeting output voltage level and short circuit current specifications, as increasing conduction resistance to comply with one specification often violates the other, and prior solutions either increase MOSFET channel widths or use clamping circuits that raise conduction resistance.
Innovation Solution
A driving stage circuit with an adaptive conduction resistance adjusting circuit that clamps switch control signals based on current levels, ensuring conduction resistance remains above a threshold to prevent short circuit current exceedance and below a threshold to maintain output voltage compliance, without increasing MOSFET channel widths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the conduction resistance of the driving switch circuit is decreased to meet the output voltage level specification, then the output voltage level compliance is improved, but the short circuit current specification is violated
Solution Approach 1:
The patent implements dynamic adjustment of conduction resistance by introducing a conduction resistance adjusting circuit that adaptively controls the switch control signal based on real-time current detection. The circuit transitions from static resistance (fixed by MOSFET channel width) to dynamic resistance adjustment, allowing the system to meet output voltage specifications during normal operation while preventing short circuit current exceedance when current exceeds thresholds.
Solution Approach 2:
The patent changes the control parameter from fixed geometric parameters (MOSFET channel width) to adjustable electrical parameters (gate voltage level). By varying the gate voltage through the conduction resistance adjusting circuit, the system can dynamically change the conduction resistance to satisfy different operational requirements, achieving both low resistance for voltage compliance and high resistance for current protection as needed.
2Object-affected harmful factors
If the conduction resistance of the driving switch circuit is increased to meet the short circuit current specification, then the short circuit current compliance is improved, but the output voltage level specification is violated
Solution Approach 1:
The conduction resistance adjusting circuit provides dynamic resistance control, switching between low-resistance mode (for voltage compliance) and high-resistance mode (for current protection) based on real-time current conditions. This dynamic behavior resolves the contradiction by allowing the system to exhibit different resistance characteristics at different operational states rather than being constrained to a fixed resistance value.
Solution Approach 2:
The patent employs a feedback mechanism where the current detection unit continuously monitors the current through the driving switch circuit and feeds this information to the conduction resistance adjusting circuit. This closed-loop feedback enables the system to automatically adjust the conduction resistance in response to current conditions, ensuring both voltage level compliance and short circuit current protection are maintained appropriately.
3Manufacturing precision
If the MOSFET channel width is increased to decrease conduction resistance, then the conduction resistance is reduced for better voltage compliance, but the circuit area and cost increase
Solution Approach 1:
Instead of changing the physical dimension parameter (channel width), the patent changes the electrical control parameter (gate voltage) to achieve the desired conduction resistance. This allows the same MOSFET device to provide different resistance values through voltage control, avoiding the need to increase device size while achieving low conduction resistance for voltage compliance.
Solution Approach 2:
The patent uses a control signal copying approach where the switch control signal is processed through the conduction resistance adjusting circuit to generate an optimized gate voltage signal. This virtual copying and transformation of the control signal allows indirect control of conduction resistance without physically enlarging the MOSFET channel, thereby reducing circuit area compared to direct geometric scaling.
Data Source
AI summary
The present invention provides a driving stage circuit, including a driving switch circuit and a conduction resistance adjusting circuit. The driving switch circuit generates an output signal according to a switch control signal. The conduction resistance adjusting circuit clamps the switch control signal to a first clamping level according to a current flowing through the driving switch circuit when the current is higher than a first current threshold, such that the conduction resistance of the driving switch circuit is not smaller than a first resistance so that a short circuit current of the driving switch circuit is not larger than a short circuit current limit, wherein a lowest level of the conduction resistance of the driving switch circuit is smaller than a second resistance and the output voltage level does not exceeds a output voltage limit when the current is lower than the first current threshold.