Sensor Stage Replicates Power Switch for Overcurrent Detection
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Solution Overview
Problem
High-speed switching converters above 100 MHz often lack effective overcurrent protection due to the high current consumption and timing accuracy requirements of fast comparators used for monitoring voltage in power switches.
Innovation Solution
A circuit that generates a continuous signal from a switched signal to detect overcurrent events, using a sensor stage with replica switching devices to replicate the condition of the power switching device, allowing for accurate detection without being pulsed with the switching frequency, and a comparator to compare this signal to a reference voltage, with a post-processing circuit to count events and flag conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If fast comparators are used to monitor instantaneous voltage of power switch, then overcurrent detection speed is improved, but current consumption increases and timing accuracy becomes difficult to maintain at high frequencies
Solution Approach 1:
The patent uses a sensor stage with replica switching devices that copies the voltage waveform from the power switch. This copy is then processed to generate a continuous signal that represents the current through the power switch, enabling detection without directly using high-speed comparators on the original high-frequency signal.
Solution Approach 2:
The patent transforms the detection approach from direct voltage comparison in the time domain to frequency domain analysis by generating a continuous signal that represents the instantaneous voltage. This dimensional transformation allows standard comparators to effectively detect overcurrent conditions at high switching frequencies.
2Measurement precision
If fast comparators are used to monitor instantaneous voltage, then detection accuracy is improved, but timing accuracy deteriorates at switching frequencies above 100 MHz
Solution Approach 1:
The sensor stage creates an accurate copy of the power switch voltage waveform using replica devices. This copied signal is then used to generate a continuous representation that maintains timing accuracy even at high switching frequencies above 100 MHz, avoiding the timing issues associated with direct high-speed comparator approaches.
3Reliability
If traditional comparator-based detection is used, then overcurrent detection capability is improved, but device complexity increases due to high-speed requirements
Solution Approach 1:
The patent employs a sensor stage that copies the voltage waveform from the power switch using replica switching devices. This copying mechanism enables reliable overcurrent detection by providing a processed, continuous signal that can be analyzed by standard comparators, thereby reducing the complexity associated with high-speed comparator requirements while maintaining effective overcurrent protection capability.
Data Source
AI summary
Embodiments include apparatuses, systems, and methods including a switching converter having an output stage including a power switch or first switching device to convert an input switching signal to an output switching signal and a sensor stage including a second switching device and a third switching device. In embodiments, the sensor stage may be coupled to receive the output switching signal from the first switching device and to substantially replicate a condition of the first switching device to generate a continuous signal rather than a switched signal. In embodiments, the continuous signal may allow detection of a current level. In some embodiments, the current level may indicate an overcurrent event. A digital post-processing circuit may be coupled to the switching device to count a number of overcurrent events according to various embodiments. Other embodiments may also be described and claimed.