Switching Voltage Regulator Current Sensing With One Shunt
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Solution Overview
Problem
Existing switching voltage regulators face challenges in efficiently controlling inductor current without high energy consumption and complex, costly designs, particularly in applications requiring current sensing on both high and low sides of the switching circuit, such as in the automotive field.
Innovation Solution
A control device for a switching voltage regulator that senses current on both high and low sides of the switching circuit using a single shunt resistor, coupled with a feedback loop and current detectors to manage current thresholds, reducing energy consumption and complexity by optimizing current control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current sensing is performed on both high and low sides of the switching circuit, then current control precision is improved, but energy consumption increases
Solution Approach 1:
The patent combines high-side and low-side current sensing into a unified control architecture where a single shunt resistor on the low side serves dual purposes: it senses both the inductor current (for peak current control) and the output current (for load regulation). This merging eliminates the need for separate sensing circuits, reducing energy consumption while maintaining precise current control capability on both sides of the switching circuit.
Solution Approach 2:
The low-side shunt resistor is designed to perform multiple functions simultaneously: it acts as the sensing element for both high-side and low-side current measurement, provides ground reference for the control circuitry, and enables both peak current mode control and output current regulation. This multi-functionality reduces the overall component count and energy consumption while achieving precise dual-sided current control.
2Measurement precision
If dual current sensing is implemented, then control accuracy is improved, but device complexity increases
Solution Approach 1:
The control device merges the high-side and low-side current sensing functions into a single integrated control loop. The same shunt resistor and ADC converter are used for both sensing purposes, and the control algorithm processes both current information sequentially within one control cycle. This merging significantly reduces device complexity compared to implementing separate sensing circuits while maintaining high control accuracy through sophisticated digital signal processing.
Solution Approach 2:
The system uses its existing low-side sensing infrastructure to serve the additional function of high-side current measurement. The control algorithm cleverly derives high-side current information from the low-side shunt measurements combined with knowledge of the switching states and voltage relationships. This self-service approach avoids adding external sensing components, thereby reducing device complexity while achieving accurate dual-sided current control.
3Reliability
If separate shunt resistors are used for high and low side sensing, then measurement reliability is improved, but cost increases
Solution Approach 1:
The patent merges the function of two separate shunt resistors into a single low-side shunt resistor. This single resistor is strategically positioned to sense both the inductor current during the switch on-time and the output current during the switch off-time. By combining these sensing functions, the patent reduces component count and manufacturing cost while maintaining measurement reliability through careful circuit design and digital signal processing that compensates for any limitations of the single-sensing approach.
Data Source
AI summary
A control device for a switching voltage regulator includes: a first detector of a first measurement signal indicative of a current flowing in a first side of the regulator, and providing a first comparison signal as a function of a first threshold; a second detector of a second measurement signal indicative of a current flowing in a second side of the regulator, and providing a second comparison signal as a function of a second threshold; a driving-signal generation circuit which generates a switching control signal from the first comparison signal to drive the switching circuit; a calibration circuit which receives an alert signal indicative of the first threshold, compares the alert signal and the second comparison signal, and provides a calibration signal in response; and a feedback circuit which provides a control signal as a function of an error signal and of the calibration signal.